Sign in

Search msp430

Subscribe to msp430

Discussion Groups

Discussion Groups | MSP430 | How to measuring the VCC by MSP430

The purpose of this group is to foster exchange of information on the Texas Instruments MSP430 family of microcontrollers and related tools. Everyone welcome, all levels of familiarity/expertise.

How to measuring the VCC by MSP430 - =?GB2312?B?zuLU8bS+?= - Aug 23 8:31:15 2009

Hi all:

We are using MSP430F2272 and CC1101 to a low power consumption solution, an=
d
want to measuring the voltage of the power supply battary, which is 3.6V
when full, and have to change it when belows 2.3V.

And now we are measuring it by a method discribed as the following, but hav=
e
some problems:

As MSP430 Vref is 2.5v, so we can't measuring the VCC with it, because the
AD will always 1023. we connect two resistances in series(one 2K and anothe=
r
1K), and open or close the current by a PNP CMOS triode, which is controle=
d
by a GPIO port(P3.6), and measuring the voltage by A7 channel.

When I want to measuring the voltage, first open the CMOS triode, and
measuring it by the A7, when finish I close the triode to save the power.

The problem is: when the two resistances is 2K and 1K, the VCC is 3.6V, and
the real voltage between R1 and R2 is about 0.9v(I measured by
oscilloscope), and measued 0.9V by the program. But after we changed R1 and
R2 to 200K and 100K, which will save more power, and the real voltage
between R1 and R2 is about 0.9v too, but it isn't correct by the program,
which is about 1.2V. When I closed the triode, the voltage is 0.3V by
program but the real is 0V.

Has anyone encountered with this strange problem? and can someone provide a
reference circurt to measuring the voltage of the supply battary? please
give me some propose, thanks in advance:)

Vcc
|
-||-----P3.6
|
R1
|
=86------P3.7(A7)
|
R2
|
---
-(GND)

--=20
Best Regards.
chernwu
[Non-text portions of this message have been removed]

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - Hendrik - Aug 23 10:10:49 2009

For my application I use a similar setup, dividing the 3.6V supply by
two 100K resistors (which effectively uses far less power than using two
1K resistors obviously and I'm not using a triode or anything, just the
plain voltage divider), and using the internal 2.5V reference of the
MSP430. A charged battery should thus give a measurement of 1.8V. When
measuring I got very strange values, but as far as I can remember I had
to changes the number of samples to be taken to a higher number to get
stable results.

Take a look at the example sources provided with the MSP430F22xx. The
file 'msp430x22x4_adc10_19.c might lead to this setting:

ADC10DTC1 = 0x040; // 64 conversions

At the moment I cannot lookup the number of conversions I used, but a
low value also yielded in inaccurate readings.

Regards,
Hendrik

吴择淳 wrote:
> Hi all:
>
> We are using MSP430F2272 and CC1101 to a low power consumption solution, and
> want to measuring the voltage of the power supply battary, which is 3.6V
> when full, and have to change it when belows 2.3V.
>
> And now we are measuring it by a method discribed as the following, but have
> some problems:
>
> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it, because the
> AD will always 1023. we connect two resistances in series(one 2K and another
> 1K), and open or close the current by a PNP CMOS triode, which is controled
> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>
> When I want to measuring the voltage, first open the CMOS triode, and
> measuring it by the A7, when finish I close the triode to save the power.
>
> The problem is: when the two resistances is 2K and 1K, the VCC is 3.6V, and
> the real voltage between R1 and R2 is about 0.9v(I measured by
> oscilloscope), and measued 0.9V by the program. But after we changed R1 and
> R2 to 200K and 100K, which will save more power, and the real voltage
> between R1 and R2 is about 0.9v too, but it isn't correct by the program,
> which is about 1.2V. When I closed the triode, the voltage is 0.3V by
> program but the real is 0V.
>
> Has anyone encountered with this strange problem? and can someone provide a
> reference circurt to measuring the voltage of the supply battary? please
> give me some propose, thanks in advance:)
>
> Vcc
> |
> -||-----P3.6
> |
> R1
> |
> â€ ------P3.7(A7)
> |
> R2
> |
> ---
> -(GND)
>
>

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 10:50:13 2009

You could always read the manual and discover the nice simple method
that the chips designers included for you to do just this with.

Al

??? wrote:
> Hi all:
>
> We are using MSP430F2272 and CC1101 to a low power consumption solution, and
> want to measuring the voltage of the power supply battary, which is 3.6V
> when full, and have to change it when belows 2.3V.
>
> And now we are measuring it by a method discribed as the following, but have
> some problems:
>
> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it, because the
> AD will always 1023. we connect two resistances in series(one 2K and another
> 1K), and open or close the current by a PNP CMOS triode, which is controled
> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>
> When I want to measuring the voltage, first open the CMOS triode, and
> measuring it by the A7, when finish I close the triode to save the power.
>
> The problem is: when the two resistances is 2K and 1K, the VCC is 3.6V, and
> the real voltage between R1 and R2 is about 0.9v(I measured by
> oscilloscope), and measued 0.9V by the program. But after we changed R1 and
> R2 to 200K and 100K, which will save more power, and the real voltage
> between R1 and R2 is about 0.9v too, but it isn't correct by the program,
> which is about 1.2V. When I closed the triode, the voltage is 0.3V by
> program but the real is 0V.
>
> Has anyone encountered with this strange problem? and can someone provide a
> reference circurt to measuring the voltage of the supply battary? please
> give me some propose, thanks in advance:)
>
> Vcc
> |
> -||-----P3.6
> |
> R1
> |
> �------P3.7(A7)
> |
> R2
> |
> ---
> -(GND)
>
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - Paul Curtis - Aug 23 10:57:08 2009

On Sun, 23 Aug 2009 15:48:45 +0100, OneStone
wrote:

> You could always read the manual and discover the nice simple method
> that the chips designers included for you to do just this with.

Sh*t, I though this mailing list was powered by SpinVox D2 and *was* the
manual for the MSP430? Have I been wilfully misled?

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks V2 is out for LPC1700, LPC3100, LPC3200, SAM9, and more!
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 11:03:48 2009

If it were me, I would use analog channel 11 (0x0B), which is (Vcc-Vss)/2. =
The divide by 2 resistors and the power-saving switch are all built-in and =
automatically enabled when I select A11.

I would also use internal 1.5V reference, not internal 2.5V reference. My r=
eason is, when Vcc drops below 2.8V, the "2.5V" reference is no longer 2.5V=
. (The 1.5V reference is still good when down to Vcc=3D2.2V.) When Vcc is a=
bove 3.0V, ADC will be saturated. Thus I will not be able to get the true v=
oltage when it is above 3.0V, but knowing that it is above 3.0V is good eno=
ugh for me.
=20
--- In m...@yahoogroups.com, Hendrik wrote:
>
> For my application I use a similar setup, dividing the 3.6V supply by
> two 100K resistors (which effectively uses far less power than using two
> 1K resistors obviously and I'm not using a triode or anything, just the
> plain voltage divider), and using the internal 2.5V reference of the
> MSP430. A charged battery should thus give a measurement of 1.8V. When
> measuring I got very strange values, but as far as I can remember I had
> to changes the number of samples to be taken to a higher number to get
> stable results.
>=20
> Take a look at the example sources provided with the MSP430F22xx. The
> file 'msp430x22x4_adc10_19.c might lead to this setting:
>=20
> ADC10DTC1 =3D 0x040; // 64 conversions
>=20
> At the moment I cannot lookup the number of conversions I used, but a
> low value also yielded in inaccurate readings.
>=20
> Regards,
> Hendrik
>=20
>=20
>=20
> =E5=90=B4=E6=8B=A9=E6=B7=B3 wrote:
> > Hi all:
> >
> > We are using MSP430F2272 and CC1101 to a low power consumption solution=
, and
> > want to measuring the voltage of the power supply battary, which is 3.6=
V
> > when full, and have to change it when belows 2.3V.
> >
> > And now we are measuring it by a method discribed as the following, but=
have
> > some problems:
> >
> > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it, because =
the
> > AD will always 1023. we connect two resistances in series(one 2K and an=
other
> > 1K), and open or close the current by a PNP CMOS triode, which is cont=
roled
> > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> >
> > When I want to measuring the voltage, first open the CMOS triode, and
> > measuring it by the A7, when finish I close the triode to save the powe=
r.
> >
> > The problem is: when the two resistances is 2K and 1K, the VCC is 3.6V,=
and
> > the real voltage between R1 and R2 is about 0.9v(I measured by
> > oscilloscope), and measued 0.9V by the program. But after we changed R1=
and
> > R2 to 200K and 100K, which will save more power, and the real voltage
> > between R1 and R2 is about 0.9v too, but it isn't correct by the progra=
m,
> > which is about 1.2V. When I closed the triode, the voltage is 0.3V by
> > program but the real is 0V.
> >
> > Has anyone encountered with this strange problem? and can someone provi=
de a
> > reference circurt to measuring the voltage of the supply battary? pleas=
e
> > give me some propose, thanks in advance:)
> >
> > Vcc
> > |
> > -||-----P3.6
> > |
> > R1
> > |
> > =C3=A2=E2=82=AC ------P3.7(A7)
> > |
> > R2
> > |
> > ---
> > -(GND)
> >
>

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 11:08:22 2009

No, this is not the manual. This is where people can demand "Send me the code. This is urgent!"

--- In m...@yahoogroups.com, "Paul Curtis" wrote:
>
> On Sun, 23 Aug 2009 15:48:45 +0100, OneStone
> wrote:
>
> > You could always read the manual and discover the nice simple method
> > that the chips designers included for you to do just this with.
>
> Sh*t, I though this mailing list was powered by SpinVox D2 and *was* the
> manual for the MSP430? Have I been wilfully misled?
>
> --
> Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
> CrossWorks V2 is out for LPC1700, LPC3100, LPC3200, SAM9, and more!
>
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 13:51:55 2009

If I were you I would have made him go and read the manual to find that
out for himself, that way he might actually learn something useful, but
you are a much crueler man than I am. ;@}

Al

old_cow_yellow wrote:
> If it were me, I would use analog channel 11 (0x0B), which is (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch are all built-in and automatically enabled when I select A11.
>
> I would also use internal 1.5V reference, not internal 2.5V reference. My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no longer 2.5V. (The 1.5V reference is still good when down to Vcc=2.2V.) When Vcc is above 3.0V, ADC will be saturated. Thus I will not be able to get the true voltage when it is above 3.0V, but knowing that it is above 3.0V is good enough for me.
>
> --- In m...@yahoogroups.com, Hendrik wrote:
>> For my application I use a similar setup, dividing the 3.6V supply by
>> two 100K resistors (which effectively uses far less power than using two
>> 1K resistors obviously and I'm not using a triode or anything, just the
>> plain voltage divider), and using the internal 2.5V reference of the
>> MSP430. A charged battery should thus give a measurement of 1.8V. When
>> measuring I got very strange values, but as far as I can remember I had
>> to changes the number of samples to be taken to a higher number to get
>> stable results.
>>
>> Take a look at the example sources provided with the MSP430F22xx. The
>> file 'msp430x22x4_adc10_19.c might lead to this setting:
>>
>> ADC10DTC1 = 0x040; // 64 conversions
>>
>> At the moment I cannot lookup the number of conversions I used, but a
>> low value also yielded in inaccurate readings.
>>
>> Regards,
>> Hendrik
>>
>> 吴择淳 wrote:
>>> Hi all:
>>>
>>> We are using MSP430F2272 and CC1101 to a low power consumption solution, and
>>> want to measuring the voltage of the power supply battary, which is 3.6V
>>> when full, and have to change it when belows 2.3V.
>>>
>>> And now we are measuring it by a method discribed as the following, but have
>>> some problems:
>>>
>>> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it, because the
>>> AD will always 1023. we connect two resistances in series(one 2K and another
>>> 1K), and open or close the current by a PNP CMOS triode, which is controled
>>> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>>>
>>> When I want to measuring the voltage, first open the CMOS triode, and
>>> measuring it by the A7, when finish I close the triode to save the power.
>>>
>>> The problem is: when the two resistances is 2K and 1K, the VCC is 3.6V, and
>>> the real voltage between R1 and R2 is about 0.9v(I measured by
>>> oscilloscope), and measued 0.9V by the program. But after we changed R1 and
>>> R2 to 200K and 100K, which will save more power, and the real voltage
>>> between R1 and R2 is about 0.9v too, but it isn't correct by the program,
>>> which is about 1.2V. When I closed the triode, the voltage is 0.3V by
>>> program but the real is 0V.
>>>
>>> Has anyone encountered with this strange problem? and can someone provide a
>>> reference circurt to measuring the voltage of the supply battary? please
>>> give me some propose, thanks in advance:)
>>>
>>> Vcc
>>> |
>>> -||-----P3.6
>>> |
>>> R1
>>> |
>>> â€ ------P3.7(A7)
>>> |
>>> R2
>>> |
>>> ---
>>> -(GND)
>>>
>>>
> ------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 23 14:48:08 2009

old_cow_yellow: so you're saying that it is not damaging to the ADC
supplying a 3.6V source when using the internal 1.5V/2.5V reference?

old_cow_yellow wrote:
>
> If it were me, I would use analog channel 11 (0x0B), which is
> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch are
> all built-in and automatically enabled when I select A11.
>
> I would also use internal 1.5V reference, not internal 2.5V reference.
> My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
> longer 2.5V. (The 1.5V reference is still good when down to Vcc=2.2V.)
> When Vcc is above 3.0V, ADC will be saturated. Thus I will not be able
> to get the true voltage when it is above 3.0V, but knowing that it is
> above 3.0V is good enough for me.
>
> --- In m...@yahoogroups.com ,
> Hendrik wrote:
> >
> > For my application I use a similar setup, dividing the 3.6V supply by
> > two 100K resistors (which effectively uses far less power than using two
> > 1K resistors obviously and I'm not using a triode or anything, just the
> > plain voltage divider), and using the internal 2.5V reference of the
> > MSP430. A charged battery should thus give a measurement of 1.8V. When
> > measuring I got very strange values, but as far as I can remember I had
> > to changes the number of samples to be taken to a higher number to get
> > stable results.
> >
> > Take a look at the example sources provided with the MSP430F22xx. The
> > file 'msp430x22x4_adc10_19.c might lead to this setting:
> >
> > ADC10DTC1 = 0x040; // 64 conversions
> >
> > At the moment I cannot lookup the number of conversions I used, but a
> > low value also yielded in inaccurate readings.
> >
> > Regards,
> > Hendrik
> >
> >
> >
> > 吴择淳 wrote:
> > > Hi all:
> > >
> > > We are using MSP430F2272 and CC1101 to a low power consumption
> solution, and
> > > want to measuring the voltage of the power supply battary, which
> is 3.6V
> > > when full, and have to change it when belows 2.3V.
> > >
> > > And now we are measuring it by a method discribed as the
> following, but have
> > > some problems:
> > >
> > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
> because the
> > > AD will always 1023. we connect two resistances in series(one 2K
> and another
> > > 1K), and open or close the current by a PNP CMOS triode, which is
> controled
> > > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> > >
> > > When I want to measuring the voltage, first open the CMOS triode, and
> > > measuring it by the A7, when finish I close the triode to save the
> power.
> > >
> > > The problem is: when the two resistances is 2K and 1K, the VCC is
> 3.6V, and
> > > the real voltage between R1 and R2 is about 0.9v(I measured by
> > > oscilloscope), and measued 0.9V by the program. But after we
> changed R1 and
> > > R2 to 200K and 100K, which will save more power, and the real voltage
> > > between R1 and R2 is about 0.9v too, but it isn't correct by the
> program,
> > > which is about 1.2V. When I closed the triode, the voltage is 0.3V by
> > > program but the real is 0V.
> > >
> > > Has anyone encountered with this strange problem? and can someone
> provide a
> > > reference circurt to measuring the voltage of the supply battary?
> please
> > > give me some propose, thanks in advance:)
> > >
> > > Vcc
> > > |
> > > -||-----P3.6
> > > |
> > > R1
> > > |
> > > â€ ------P3.7(A7)
> > > |
> > > R2
> > > |
> > > ---
> > > -(GND)
> > >
> > >
> >
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 15:14:25 2009

No it isn't. Read the users guide. Channel 11 selects (Vcc-Vss)/2 as the
input signal to be read by that channel. This has been a feature of
every SAR ADC on the MSP that I can think of having used since the
original 149

Al

Hendrik wrote:
> old_cow_yellow: so you're saying that it is not damaging to the ADC
> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
>
> old_cow_yellow wrote:
>> If it were me, I would use analog channel 11 (0x0B), which is
>> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch are
>> all built-in and automatically enabled when I select A11.
>>
>> I would also use internal 1.5V reference, not internal 2.5V reference.
>> My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
>> longer 2.5V. (The 1.5V reference is still good when down to Vcc=2.2V.)
>> When Vcc is above 3.0V, ADC will be saturated. Thus I will not be able
>> to get the true voltage when it is above 3.0V, but knowing that it is
>> above 3.0V is good enough for me.
>>
>> --- In m...@yahoogroups.com ,
>> Hendrik wrote:
>>> For my application I use a similar setup, dividing the 3.6V supply by
>>> two 100K resistors (which effectively uses far less power than using two
>>> 1K resistors obviously and I'm not using a triode or anything, just the
>>> plain voltage divider), and using the internal 2.5V reference of the
>>> MSP430. A charged battery should thus give a measurement of 1.8V. When
>>> measuring I got very strange values, but as far as I can remember I had
>>> to changes the number of samples to be taken to a higher number to get
>>> stable results.
>>>
>>> Take a look at the example sources provided with the MSP430F22xx. The
>>> file 'msp430x22x4_adc10_19.c might lead to this setting:
>>>
>>> ADC10DTC1 = 0x040; // 64 conversions
>>>
>>> At the moment I cannot lookup the number of conversions I used, but a
>>> low value also yielded in inaccurate readings.
>>>
>>> Regards,
>>> Hendrik
>>>
>>>
>>>
>>> 吴择淳 wrote:
>>>> Hi all:
>>>>
>>>> We are using MSP430F2272 and CC1101 to a low power consumption
>> solution, and
>>>> want to measuring the voltage of the power supply battary, which
>> is 3.6V
>>>> when full, and have to change it when belows 2.3V.
>>>>
>>>> And now we are measuring it by a method discribed as the
>> following, but have
>>>> some problems:
>>>>
>>>> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
>> because the
>>>> AD will always 1023. we connect two resistances in series(one 2K
>> and another
>>>> 1K), and open or close the current by a PNP CMOS triode, which is
>> controled
>>>> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>>>>
>>>> When I want to measuring the voltage, first open the CMOS triode, and
>>>> measuring it by the A7, when finish I close the triode to save the
>> power.
>>>> The problem is: when the two resistances is 2K and 1K, the VCC is
>> 3.6V, and
>>>> the real voltage between R1 and R2 is about 0.9v(I measured by
>>>> oscilloscope), and measued 0.9V by the program. But after we
>> changed R1 and
>>>> R2 to 200K and 100K, which will save more power, and the real voltage
>>>> between R1 and R2 is about 0.9v too, but it isn't correct by the
>> program,
>>>> which is about 1.2V. When I closed the triode, the voltage is 0.3V by
>>>> program but the real is 0V.
>>>>
>>>> Has anyone encountered with this strange problem? and can someone
>> provide a
>>>> reference circurt to measuring the voltage of the supply battary?
>> please
>>>> give me some propose, thanks in advance:)
>>>>
>>>> Vcc
>>>> |
>>>> -||-----P3.6
>>>> |
>>>> R1
>>>> |
>>>> â€ ------P3.7(A7)
>>>> |
>>>> R2
>>>> |
>>>> ---
>>>> -(GND)
>>>>
>>> ------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 16:00:12 2009

No, I did not say that.

VREF+/- are not the limits for ADC input. When ADC input is higher than VRE=
F+, you get 1023. When ADC input is lower than VREF-, you get 0.

The limits of both VREF+/- and ADC inputs are AVcc and AVss (the power rail=
).

--- In m...@yahoogroups.com, Hendrik wrote:
>
> old_cow_yellow: so you're saying that it is not damaging to the ADC=20
> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
>=20
> old_cow_yellow wrote:
> >
> > If it were me, I would use analog channel 11 (0x0B), which is=20
> > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch are=
=20
> > all built-in and automatically enabled when I select A11.
> >
> > I would also use internal 1.5V reference, not internal 2.5V reference.=
=20
> > My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no=20
> > longer 2.5V. (The 1.5V reference is still good when down to Vcc=3D2.2V.=
)=20
> > When Vcc is above 3.0V, ADC will be saturated. Thus I will not be able=
=20
> > to get the true voltage when it is above 3.0V, but knowing that it is=20
> > above 3.0V is good enough for me.
> >
> > --- In m...@yahoogroups.com ,=20
> > Hendrik wrote:
> > >
> > > For my application I use a similar setup, dividing the 3.6V supply by
> > > two 100K resistors (which effectively uses far less power than using =
two
> > > 1K resistors obviously and I'm not using a triode or anything, just t=
he
> > > plain voltage divider), and using the internal 2.5V reference of the
> > > MSP430. A charged battery should thus give a measurement of 1.8V. Whe=
n
> > > measuring I got very strange values, but as far as I can remember I h=
ad
> > > to changes the number of samples to be taken to a higher number to ge=
t
> > > stable results.
> > >
> > > Take a look at the example sources provided with the MSP430F22xx. The
> > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > >
> > > ADC10DTC1 =3D 0x040; // 64 conversions
> > >
> > > At the moment I cannot lookup the number of conversions I used, but a
> > > low value also yielded in inaccurate readings.
> > >
> > > Regards,
> > > Hendrik
> > >
> > >
> > >
> > > =E5=90=B4=E6=8B=A9=E6=B7=B3 wrote:
> > > > Hi all:
> > > >
> > > > We are using MSP430F2272 and CC1101 to a low power consumption=20
> > solution, and
> > > > want to measuring the voltage of the power supply battary, which=20
> > is 3.6V
> > > > when full, and have to change it when belows 2.3V.
> > > >
> > > > And now we are measuring it by a method discribed as the=20
> > following, but have
> > > > some problems:
> > > >
> > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,=20
> > because the
> > > > AD will always 1023. we connect two resistances in series(one 2K=20
> > and another
> > > > 1K), and open or close the current by a PNP CMOS triode, which is=20
> > controled
> > > > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> > > >
> > > > When I want to measuring the voltage, first open the CMOS triode, a=
nd
> > > > measuring it by the A7, when finish I close the triode to save the=
=20
> > power.
> > > >
> > > > The problem is: when the two resistances is 2K and 1K, the VCC is=20
> > 3.6V, and
> > > > the real voltage between R1 and R2 is about 0.9v(I measured by
> > > > oscilloscope), and measued 0.9V by the program. But after we=20
> > changed R1 and
> > > > R2 to 200K and 100K, which will save more power, and the real volta=
ge
> > > > between R1 and R2 is about 0.9v too, but it isn't correct by the=20
> > program,
> > > > which is about 1.2V. When I closed the triode, the voltage is 0.3V =
by
> > > > program but the real is 0V.
> > > >
> > > > Has anyone encountered with this strange problem? and can someone=20
> > provide a
> > > > reference circurt to measuring the voltage of the supply battary?=20
> > please
> > > > give me some propose, thanks in advance:)
> > > >
> > > > Vcc
> > > > |
> > > > -||-----P3.6
> > > > |
> > > > R1
> > > > |
> > > > =C3=A2=E2=82=AC ------P3.7(A7)
> > > > |
> > > > R2
> > > > |
> > > > ---
> > > > -(GND)
> > > >
> > > >
> > >
> >
>

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Paul Curtis - Aug 23 17:19:08 2009

On Sun, 23 Aug 2009 16:07:38 +0100, old_cow_yellow
wrote:

> No, this is not the manual. This is where people can demand "Send me the
> code. This is urgent!"

I really thought this was a front end onto an on-line
natural-language-query database populated with all analog, digital, and
system integration expertese?

I also believed the excellent technology behind this facility was funded
from on high? I mean, you don't get all these reponses from HUMANs, you'd
never be able to get a human to croak up all his expertise for nowt.

I am SADLY mistaken, it seems. :-(

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
CrossWorks V2 is out for LPC1700, LPC3100, LPC3200, SAM9, and more!
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - p_murayama - Aug 23 21:28:28 2009

Hello!

What an excellent reply!
Next time somebody asks me for his way in Kyoto, i'll reply "read the map and
discover how easy it is to go just where you want".

Pascal

--- In m...@yahoogroups.com, OneStone wrote:
>
> You could always read the manual and discover the nice simple method
> that the chips designers included for you to do just this with.
>
> Al
>
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - =?GB2312?B?zuLU8bS+?= - Aug 23 21:54:40 2009

Thanks for you all, and many thanks to old_cow_yellow:)

It works great fine after set A11. and when i refered to User's Guide>, Figure 20-1. ADC10 Block Diagram on page 20-3 says much
clear:)

2009/8/24 p_murayama

> Hello!
>
> What an excellent reply!
> Next time somebody asks me for his way in Kyoto, i'll reply "read the map
> and
> discover how easy it is to go just where you want".
>
> Pascal
> --- In m...@yahoogroups.com , OneStone
> wrote:
> >
> > You could always read the manual and discover the nice simple method
> > that the chips designers included for you to do just this with.
> >
> > Al
> >=20=20
>

--=20
Best Regards.
=CE=E2=D4=F1=B4=BE
------------------------------------------
=B1=B1=BE=A9=BA=A3=D2=C4=C4=C9=BF=C6=BC=BC=B7=A2=D5=B9=D3=D0=CF=DE=B9=AB=CB=
=BE
MSN: c...@hotmail.com
EMail: c...@gmail.com
[Non-text portions of this message have been removed]

------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 10:18:01 2009

This forum is not Kyoto, it's for people that after doing their homework, reading and googling still can't find a solution, or for people who just want to contribute or discuss a topic. It is NOT for people just passing by to quickly get directions. Your example is not applicable, not even in the slightest.

OneStone directed the OP to where the answer layed, so the OP may find the answer for himself, which will in the long run be far more beneficial to the OP.

Michael K.

--- In m...@yahoogroups.com, "p_murayama" wrote:
>
> Hello!
>
> What an excellent reply!
> Next time somebody asks me for his way in Kyoto, i'll reply "read the map and
> discover how easy it is to go just where you want".
>
> Pascal
>
> --- In m...@yahoogroups.com, OneStone wrote:
> >
> > You could always read the manual and discover the nice simple method
> > that the chips designers included for you to do just this with.
> >
> > Al
>

------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 24 10:44:51 2009

I thought you were from New York.

--- In m...@yahoogroups.com, "p_murayama" wrote:
>
> Hello!
>
> What an excellent reply!
> Next time somebody asks me for his way in Kyoto, i'll reply "read the map and
> discover how easy it is to go just where you want".
>
> Pascal
>
> --- In m...@yahoogroups.com, OneStone wrote:
> >
> > You could always read the manual and discover the nice simple method
> > that the chips designers included for you to do just this with.
> >
> > Al
>

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 10:45:40 2009

Haven't you yet got the hint to RTFM prior to asking questions?
The input voltage range is a parameter that has to be described in the Data=
sheet, just like any other voltage characteristic.
The answer is right where it should be: look for the MSP430F2272 datasheet =
(not User Guide), search for the chapter descibing the MSP Electric Charact=
eristics and then the page that descibes the ADC input range.

Michael K.

--- In m...@yahoogroups.com, Hendrik wrote:
>
> old_cow_yellow: so you're saying that it is not damaging to the ADC=20
> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
>=20
> old_cow_yellow wrote:
> >
> > If it were me, I would use analog channel 11 (0x0B), which is=20
> > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch are=
=20
> > all built-in and automatically enabled when I select A11.
> >
> > I would also use internal 1.5V reference, not internal 2.5V reference.=
=20
> > My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no=20
> > longer 2.5V. (The 1.5V reference is still good when down to Vcc=3D2.2V.=
)=20
> > When Vcc is above 3.0V, ADC will be saturated. Thus I will not be able=
=20
> > to get the true voltage when it is above 3.0V, but knowing that it is=20
> > above 3.0V is good enough for me.
> >
> > --- In m...@yahoogroups.com ,=20
> > Hendrik wrote:
> > >
> > > For my application I use a similar setup, dividing the 3.6V supply by
> > > two 100K resistors (which effectively uses far less power than using =
two
> > > 1K resistors obviously and I'm not using a triode or anything, just t=
he
> > > plain voltage divider), and using the internal 2.5V reference of the
> > > MSP430. A charged battery should thus give a measurement of 1.8V. Whe=
n
> > > measuring I got very strange values, but as far as I can remember I h=
ad
> > > to changes the number of samples to be taken to a higher number to ge=
t
> > > stable results.
> > >
> > > Take a look at the example sources provided with the MSP430F22xx. The
> > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > >
> > > ADC10DTC1 =3D 0x040; // 64 conversions
> > >
> > > At the moment I cannot lookup the number of conversions I used, but a
> > > low value also yielded in inaccurate readings.
> > >
> > > Regards,
> > > Hendrik
> > >
> > >
> > >
> > > =E5�=B4=E6�=A9=E6=B7=B3 wrote:
> > > > Hi all:
> > > >
> > > > We are using MSP430F2272 and CC1101 to a low power consumption=20
> > solution, and
> > > > want to measuring the voltage of the power supply battary, which=20
> > is 3.6V
> > > > when full, and have to change it when belows 2.3V.
> > > >
> > > > And now we are measuring it by a method discribed as the=20
> > following, but have
> > > > some problems:
> > > >
> > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,=20
> > because the
> > > > AD will always 1023. we connect two resistances in series(one 2K=20
> > and another
> > > > 1K), and open or close the current by a PNP CMOS triode, which is=20
> > controled
> > > > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> > > >
> > > > When I want to measuring the voltage, first open the CMOS triode, a=
nd
> > > > measuring it by the A7, when finish I close the triode to save the=
=20
> > power.
> > > >
> > > > The problem is: when the two resistances is 2K and 1K, the VCC is=20
> > 3.6V, and
> > > > the real voltage between R1 and R2 is about 0.9v(I measured by
> > > > oscilloscope), and measued 0.9V by the program. But after we=20
> > changed R1 and
> > > > R2 to 200K and 100K, which will save more power, and the real volta=
ge
> > > > between R1 and R2 is about 0.9v too, but it isn't correct by the=20
> > program,
> > > > which is about 1.2V. When I closed the triode, the voltage is 0.3V =
by
> > > > program but the real is 0V.
> > > >
> > > > Has anyone encountered with this strange problem? and can someone=20
> > provide a
> > > > reference circurt to measuring the voltage of the supply battary?=20
> > please
> > > > give me some propose, thanks in advance:)
> > > >
> > > > Vcc
> > > > |
> > > > -||-----P3.6
> > > > |
> > > > R1
> > > > |
> > > > =C3=A2=E2�=AC ------P3.7(A7)
> > > > |
> > > > R2
> > > > |
> > > > ---
> > > > -(GND)
> > > >
> > > >
> > >
> >
>

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 11:25:39 2009

Isn't Kyoto a suburb of New York, damn, must have misread the damn map,
now what's the address of the wherethefcukamiinkyoto news group.

Al

old_cow_yellow wrote:
> I thought you were from New York.
>
> --- In m...@yahoogroups.com, "p_murayama" wrote:
>> Hello!
>>
>> What an excellent reply!
>> Next time somebody asks me for his way in Kyoto, i'll reply "read the map and
>> discover how easy it is to go just where you want".
>>
>> Pascal
>>
>> --- In m...@yahoogroups.com, OneStone wrote:
>>> You could always read the manual and discover the nice simple method
>>> that the chips designers included for you to do just this with.
>>>
>>> Al
>>>
> ------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 24 12:00:34 2009

Wow, I hijacked a topic with just a short question as a follow-up to an
answer, just to hear if it wouldn't hurt to use an input voltage above
the reference voltage and everyone is on top of me all of a sudden :S ?!@

I know the input range is specified between 0 and VCC but the sheet also
says that you only get valid results if the voltage is in range of the
reference voltage. I don't think it's a stupid question to ask what
happens if the input voltage for the ADC higher than the reference
voltage (but indeed lower than VCC), in terms of 'damaging' to the ADC.

Anyway, it was just a simple sub-question. The topic starter's question
was about misreading the results and my answer was that he maybe didn't
take enough samples to get a stable result, because I experienced the
same misreading using relatively high resistor values.

Thanks for the A11 tip old_cow_yellow, I did not know that (and I have
to use a pin not connected to A11).

Regards,
Hendrik

tintronic wrote:
>
>
> Haven't you yet got the hint to RTFM prior to asking questions?
> The input voltage range is a parameter that has to be described in the
> Datasheet, just like any other voltage characteristic.
> The answer is right where it should be: look for the MSP430F2272
> datasheet (not User Guide), search for the chapter descibing the MSP
> Electric Characteristics and then the page that descibes the ADC input
> range.
>
> Michael K.
>
> --- In m...@yahoogroups.com ,
> Hendrik wrote:
> >
> > old_cow_yellow: so you're saying that it is not damaging to the ADC
> > supplying a 3.6V source when using the internal 1.5V/2.5V reference?
> >
> > old_cow_yellow wrote:
> > >
> > > If it were me, I would use analog channel 11 (0x0B), which is
> > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch
> are
> > > all built-in and automatically enabled when I select A11.
> > >
> > > I would also use internal 1.5V reference, not internal 2.5V
> reference.
> > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
> > > longer 2.5V. (The 1.5V reference is still good when down to
> Vcc=2.2V.)
> > > When Vcc is above 3.0V, ADC will be saturated. Thus I will not be
> able
> > > to get the true voltage when it is above 3.0V, but knowing that it is
> > > above 3.0V is good enough for me.
> > >
> > > --- In m...@yahoogroups.com
> ,
> > > Hendrik wrote:
> > > >
> > > > For my application I use a similar setup, dividing the 3.6V
> supply by
> > > > two 100K resistors (which effectively uses far less power than
> using two
> > > > 1K resistors obviously and I'm not using a triode or anything,
> just the
> > > > plain voltage divider), and using the internal 2.5V reference of the
> > > > MSP430. A charged battery should thus give a measurement of
> 1.8V. When
> > > > measuring I got very strange values, but as far as I can
> remember I had
> > > > to changes the number of samples to be taken to a higher number
> to get
> > > > stable results.
> > > >
> > > > Take a look at the example sources provided with the
> MSP430F22xx. The
> > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > > >
> > > > ADC10DTC1 = 0x040; // 64 conversions
> > > >
> > > > At the moment I cannot lookup the number of conversions I used,
> but a
> > > > low value also yielded in inaccurate readings.
> > > >
> > > > Regards,
> > > > Hendrik
> > > >
> > > >
> > > >
> > > > ��淳 wrote:
> > > > > Hi all:
> > > > >
> > > > > We are using MSP430F2272 and CC1101 to a low power consumption
> > > solution, and
> > > > > want to measuring the voltage of the power supply battary, which
> > > is 3.6V
> > > > > when full, and have to change it when belows 2.3V.
> > > > >
> > > > > And now we are measuring it by a method discribed as the
> > > following, but have
> > > > > some problems:
> > > > >
> > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
> > > because the
> > > > > AD will always 1023. we connect two resistances in series(one 2K
> > > and another
> > > > > 1K), and open or close the current by a PNP CMOS triode, which is
> > > controled
> > > > > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> > > > >
> > > > > When I want to measuring the voltage, first open the CMOS
> triode, and
> > > > > measuring it by the A7, when finish I close the triode to save
> the
> > > power.
> > > > >
> > > > > The problem is: when the two resistances is 2K and 1K, the VCC is
> > > 3.6V, and
> > > > > the real voltage between R1 and R2 is about 0.9v(I measured by
> > > > > oscilloscope), and measued 0.9V by the program. But after we
> > > changed R1 and
> > > > > R2 to 200K and 100K, which will save more power, and the real
> voltage
> > > > > between R1 and R2 is about 0.9v too, but it isn't correct by the
> > > program,
> > > > > which is about 1.2V. When I closed the triode, the voltage is
> 0.3V by
> > > > > program but the real is 0V.
> > > > >
> > > > > Has anyone encountered with this strange problem? and can someone
> > > provide a
> > > > > reference circurt to measuring the voltage of the supply battary?
> > > please
> > > > > give me some propose, thanks in advance:)
> > > > >
> > > > > Vcc
> > > > > |
> > > > > -||-----P3.6
> > > > > |
> > > > > R1
> > > > > |
> > > > > â�� ------P3.7(A7)
> > > > > |
> > > > > R2
> > > > > |
> > > > > ---
> > > > > -(GND)
> > > > >
> > > > >
> > > >
> > >
> > >
> >
------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 12:19:34 2009

You still don't quite get it. A11 is an internal analog channel which
you can assign to any of the virtual channels of the sequencer. That is
the MSP430 automatically derives (VCC-VSS)/2 for you and neatly presents
it for use if required. And if you input a signal that is below VCC but
above Vref it will read ADCMAX, ie 0x0FFF on an ADC12 and 0x03FF on an
ADC10, but ALL of that information is still contained in the manual.
Anyway there is no need to do that since Vcc/2 fits neatly with the 2.5V
reference until Vcc falls below 2.8V, but your system should be checking
for that anyway.

Al

Hendrik wrote:
> Wow, I hijacked a topic with just a short question as a follow-up to an
> answer, just to hear if it wouldn't hurt to use an input voltage above
> the reference voltage and everyone is on top of me all of a sudden :S ?!@
>
> I know the input range is specified between 0 and VCC but the sheet also
> says that you only get valid results if the voltage is in range of the
> reference voltage. I don't think it's a stupid question to ask what
> happens if the input voltage for the ADC higher than the reference
> voltage (but indeed lower than VCC), in terms of 'damaging' to the ADC.
>
> Anyway, it was just a simple sub-question. The topic starter's question
> was about misreading the results and my answer was that he maybe didn't
> take enough samples to get a stable result, because I experienced the
> same misreading using relatively high resistor values.
>
> Thanks for the A11 tip old_cow_yellow, I did not know that (and I have
> to use a pin not connected to A11).
>
> Regards,
> Hendrik
>
> tintronic wrote:
>>
>>
>> Haven't you yet got the hint to RTFM prior to asking questions?
>> The input voltage range is a parameter that has to be described in the
>> Datasheet, just like any other voltage characteristic.
>> The answer is right where it should be: look for the MSP430F2272
>> datasheet (not User Guide), search for the chapter descibing the MSP
>> Electric Characteristics and then the page that descibes the ADC input
>> range.
>>
>> Michael K.
>>
>> --- In m...@yahoogroups.com ,
>> Hendrik wrote:
>>> old_cow_yellow: so you're saying that it is not damaging to the ADC
>>> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
>>>
>>> old_cow_yellow wrote:
>>>> If it were me, I would use analog channel 11 (0x0B), which is
>>>> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch
>> are
>>>> all built-in and automatically enabled when I select A11.
>>>>
>>>> I would also use internal 1.5V reference, not internal 2.5V
>> reference.
>>>> My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
>>>> longer 2.5V. (The 1.5V reference is still good when down to
>> Vcc=2.2V.)
>>>> When Vcc is above 3.0V, ADC will be saturated. Thus I will not be
>> able
>>>> to get the true voltage when it is above 3.0V, but knowing that it is
>>>> above 3.0V is good enough for me.
>>>>
>>>> --- In m...@yahoogroups.com
>> ,
>>>> Hendrik wrote:
>>>>> For my application I use a similar setup, dividing the 3.6V
>> supply by
>>>>> two 100K resistors (which effectively uses far less power than
>> using two
>>>>> 1K resistors obviously and I'm not using a triode or anything,
>> just the
>>>>> plain voltage divider), and using the internal 2.5V reference of the
>>>>> MSP430. A charged battery should thus give a measurement of
>> 1.8V. When
>>>>> measuring I got very strange values, but as far as I can
>> remember I had
>>>>> to changes the number of samples to be taken to a higher number
>> to get
>>>>> stable results.
>>>>>
>>>>> Take a look at the example sources provided with the
>> MSP430F22xx. The
>>>>> file 'msp430x22x4_adc10_19.c might lead to this setting:
>>>>>
>>>>> ADC10DTC1 = 0x040; // 64 conversions
>>>>>
>>>>> At the moment I cannot lookup the number of conversions I used,
>> but a
>>>>> low value also yielded in inaccurate readings.
>>>>>
>>>>> Regards,
>>>>> Hendrik
>>>>>
>>>>>
>>>>>
>>>>> ��淳 wrote:
>>>>>> Hi all:
>>>>>>
>>>>>> We are using MSP430F2272 and CC1101 to a low power consumption
>>>> solution, and
>>>>>> want to measuring the voltage of the power supply battary, which
>>>> is 3.6V
>>>>>> when full, and have to change it when belows 2.3V.
>>>>>>
>>>>>> And now we are measuring it by a method discribed as the
>>>> following, but have
>>>>>> some problems:
>>>>>>
>>>>>> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
>>>> because the
>>>>>> AD will always 1023. we connect two resistances in series(one 2K
>>>> and another
>>>>>> 1K), and open or close the current by a PNP CMOS triode, which is
>>>> controled
>>>>>> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>>>>>>
>>>>>> When I want to measuring the voltage, first open the CMOS
>> triode, and
>>>>>> measuring it by the A7, when finish I close the triode to save
>> the
>>>> power.
>>>>>> The problem is: when the two resistances is 2K and 1K, the VCC is
>>>> 3.6V, and
>>>>>> the real voltage between R1 and R2 is about 0.9v(I measured by
>>>>>> oscilloscope), and measued 0.9V by the program. But after we
>>>> changed R1 and
>>>>>> R2 to 200K and 100K, which will save more power, and the real
>> voltage
>>>>>> between R1 and R2 is about 0.9v too, but it isn't correct by the
>>>> program,
>>>>>> which is about 1.2V. When I closed the triode, the voltage is
>> 0.3V by
>>>>>> program but the real is 0V.
>>>>>>
>>>>>> Has anyone encountered with this strange problem? and can someone
>>>> provide a
>>>>>> reference circurt to measuring the voltage of the supply battary?
>>>> please
>>>>>> give me some propose, thanks in advance:)
>>>>>>
>>>>>> Vcc
>>>>>> |
>>>>>> -||-----P3.6
>>>>>> |
>>>>>> R1
>>>>>> |
>>>>>> â�� ------P3.7(A7)
>>>>>> |
>>>>>> R2
>>>>>> |
>>>>>> ---
>>>>>> -(GND)
>>>>>>
>>>>>>
>>> ------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Augusto Einsfeldt - Aug 24 12:26:43 2009

Hendrik,
When the source impedance is high the reading will result in error due to t=
he=20
interaction with the ADC's input impedance.
In order to not add erros the source's impedance must be at least 2^(n+1) l=
ower=20
than the ADC's impedance (n is ADC's number of bits).
For example the F1611's data sheets suggest Rs equal or less than 400ohms w=
hen=20
using the fastest possible conversion. It can be higher with a proportional=
y=20
higher sampling time.
Of course, the internal MUX ON resistance must be accounted, too.
This is why a simple resistor divider cannot be used in the ADC's input unl=
ess it=20
is very low impedance. The solution is to use an operational amplifier as b=
uffer.
-Augusto
On Seg 24/08/09 12:58 , Hendrik c...@yahoo.com sent:
> Wow, I hijacked a topic with just a short question as a follow-up to
> an=20
> answer, just to hear if it wouldn't hurt to use an input voltage
> above=20
> the reference voltage and everyone is on top of me all of a sudden
> :S ?!@
> I know the input range is specified between 0 and VCC but the sheet
> also=20
> says that you only get valid results if the voltage is in range of
> the=20
> reference voltage. I don't think it's a stupid question to ask what=20
> happens if the input voltage for the ADC higher than the reference=20
> voltage (but indeed lower than VCC), in terms of 'damaging' to the
> ADC.
> Anyway, it was just a simple sub-question. The topic starter's
> question=20
> was about misreading the results and my answer was that he maybe
> didn't=20
> take enough samples to get a stable result, because I experienced
> the=20
> same misreading using relatively high resistor values.
> Thanks for the A11 tip old_cow_yellow, I did not know that (and I
> have=20
> to use a pin not connected to A11).
> Regards,
> Hendrik
> tintronic wrote:
> >=20=20
> >
> > Haven't you yet got the hint to RTFM prior to asking questions?
> > The input voltage range is a parameter that has to be described in
> the=20
> > Datasheet, just like any other voltage characteristic.
> > The answer is right where it should be: look for the MSP430F2272=20
> > datasheet (not User Guide), search for the chapter descibing the
> MSP=20
> > Electric Characteristics and then the page that descibes the ADC
> input=20
> > range.
> >
> > Michael K.
> >
> > --- In m...@yahoogroups.com ,=20
> > Hendrik wrote:
> > >
> > > old_cow_yellow: so you're saying that it is not damaging to the
> ADC
> > > supplying a 3.6V source when using the internal 1.5V/2.5V
> reference?
> > >
> > > old_cow_yellow wrote:
> > > >
> > > > If it were me, I would use analog channel 11 (0x0B), which is
> > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
> switch=20
> > are
> > > > all built-in and automatically enabled when I select A11.
> > > >
> > > > I would also use internal 1.5V reference, not internal 2.5V=20
> > reference.
> > > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference
> is no
> > > > longer 2.5V. (The 1.5V reference is still good when down to=20
> > Vcc=3D2.2V.)
> > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will not
> be=20
> > able
> > > > to get the true voltage when it is above 3.0V, but knowing
> that it is
> > > > above 3.0V is good enough for me.
> > > >
> > > > --- In m...@yahoogroups.com=20=20
> > ,
> > > > Hendrik wrote:
> > > > >
> > > > > For my application I use a similar setup, dividing the 3.6V=20
> > supply by
> > > > > two 100K resistors (which effectively uses far less power
> than=20
> > using two
> > > > > 1K resistors obviously and I'm not using a triode or
> anything,=20
> > just the
> > > > > plain voltage divider), and using the internal 2.5V
> reference of the
> > > > > MSP430. A charged battery should thus give a measurement of=20
> > 1.8V. When
> > > > > measuring I got very strange values, but as far as I can=20
> > remember I had
> > > > > to changes the number of samples to be taken to a higher
> number=20
> > to get
> > > > > stable results.
> > > > >
> > > > > Take a look at the example sources provided with the=20
> > MSP430F22xx. The
> > > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > > > >
> > > > > ADC10DTC1 =3D 0x040; // 64 conversions
> > > > >
> > > > > At the moment I cannot lookup the number of conversions I
> used,=20
> > but a
> > > > > low value also yielded in inaccurate readings.
> > > > >
> > > > > Regards,
> > > > > Hendrik
> > > > >
> > > > >
> > > > >
> > > > > =C3=A5=EF=BF=BD=C2=B4=C3=A6=EF=BF=BD=C2=A9=C3=A6=C2=B7=C2=B3 wrot=
e:
> > > > > > Hi all:
> > > > > >
> > > > > > We are using MSP430F2272 and CC1101 to a low power
> consumption
> > > > solution, and
> > > > > > want to measuring the voltage of the power supply battary,
> which
> > > > is 3.6V
> > > > > > when full, and have to change it when belows 2.3V.
> > > > > >
> > > > > > And now we are measuring it by a method discribed as the
> > > > following, but have
> > > > > > some problems:
> > > > > >
> > > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with
> it,
> > > > because the
> > > > > > AD will always 1023. we connect two resistances in
> series(one 2K
> > > > and another
> > > > > > 1K), and open or close the current by a PNP CMOS triode,
> which is
> > > > controled
> > > > > > by a GPIO port(P3.6), and measuring the voltage by A7
> channel.
> > > > > >
> > > > > > When I want to measuring the voltage, first open the CMOS=20
> > triode, and
> > > > > > measuring it by the A7, when finish I close the triode to
> save=20
> > the
> > > > power.
> > > > > >
> > > > > > The problem is: when the two resistances is 2K and 1K, the
> VCC is
> > > > 3.6V, and
> > > > > > the real voltage between R1 and R2 is about 0.9v(I
> measured by
> > > > > > oscilloscope), and measued 0.9V by the program. But after
> we
> > > > changed R1 and
> > > > > > R2 to 200K and 100K, which will save more power, and the
> real=20
> > voltage
> > > > > > between R1 and R2 is about 0.9v too, but it isn't correct
> by the
> > > > program,
> > > > > > which is about 1.2V. When I closed the triode, the voltage
> is=20
> > 0.3V by
> > > > > > program but the real is 0V.
> > > > > >
> > > > > > Has anyone encountered with this strange problem? and can
> someone
> > > > provide a
> > > > > > reference circurt to measuring the voltage of the supply
> battary?
> > > > please
> > > > > > give me some propose, thanks in advance:)
> > > > > >
> > > > > > Vcc
> > > > > > |
> > > > > > -||-----P3.6
> > > > > > |
> > > > > > R1
> > > > > > |
> > > > > > =C3=83=C2=A2=C3=A2=EF=BF=BD=C2=AC ------P3.7(A7)
> > > > > > |
> > > > > > R2
> > > > > > |
> > > > > > ---
> > > > > > -(GND)
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >=20
>=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
>=20

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Hugh Molesworth - Aug 24 12:58:10 2009

In addition for a higher source impedance you=20
will typically have to open out (lengthen) the=20
sample time since the higher source impedance=20
takes longer to charge associated capacitance on the ADC input pin.
Hugh

At 09:25 AM 8/24/2009, you wrote:
>Hendrik,
>When the source impedance is high the reading will result in error due to =
the
>interaction with the ADC's input impedance.
>In order to not add erros the source's impedance=20
>must be at least 2^(n+1) lower
>than the ADC's impedance (n is ADC's number of bits).
>For example the F1611's data sheets suggest Rs=20
>equal or less than 400ohms when
>using the fastest possible conversion. It can be higher with a proportiona=
ly
>higher sampling time.
>Of course, the internal MUX ON resistance must be accounted, too.
>This is why a simple resistor divider cannot be=20
>used in the ADC's input unless it
>is very low impedance. The solution is to use an=20
>operational amplifier as buffer.
>-Augusto
>On Seg 24/08/09 12:58 , Hendrik c...@yahoo.com sent:
> > Wow, I hijacked a topic with just a short question as a follow-up to
> > an
> > answer, just to hear if it wouldn't hurt to use an input voltage
> > above
> > the reference voltage and everyone is on top of me all of a sudden
> > :S ?!@
> > I know the input range is specified between 0 and VCC but the sheet
> > also
> > says that you only get valid results if the voltage is in range of
> > the
> > reference voltage. I don't think it's a stupid question to ask what
> > happens if the input voltage for the ADC higher than the reference
> > voltage (but indeed lower than VCC), in terms of 'damaging' to the
> > ADC.
> > Anyway, it was just a simple sub-question. The topic starter's
> > question
> > was about misreading the results and my answer was that he maybe
> > didn't
> > take enough samples to get a stable result, because I experienced
> > the
> > same misreading using relatively high resistor values.
> > Thanks for the A11 tip old_cow_yellow, I did not know that (and I
> > have
> > to use a pin not connected to A11).
> > Regards,
> > Hendrik
> > tintronic wrote:
> > >
> > >
> > > Haven't you yet got the hint to RTFM prior to asking questions?
> > > The input voltage range is a parameter that has to be described in
> > the
> > > Datasheet, just like any other voltage characteristic.
> > > The answer is right where it should be: look for the MSP430F2272
> > > datasheet (not User Guide), search for the chapter descibing the
> > MSP
> > > Electric Characteristics and then the page that descibes the ADC
> > input
> > > range.
> > >
> > > Michael K.
> > >
> > > --- In m...@yahoogroups.com ,
> > > Hendrik wrote:
> > > >
> > > > old_cow_yellow: so you're saying that it is not damaging to the
> > ADC
> > > > supplying a 3.6V source when using the internal 1.5V/2.5V
> > reference?
> > > >
> > > > old_cow_yellow wrote:
> > > > >
> > > > > If it were me, I would use analog channel 11 (0x0B), which is
> > > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
> > switch
> > > are
> > > > > all built-in and automatically enabled when I select A11.
> > > > >
> > > > > I would also use internal 1.5V reference, not internal 2.5V
> > > reference.
> > > > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference
> > is no
> > > > > longer 2.5V. (The 1.5V reference is still good when down to
> > > Vcc=3D2.2V.)
> > > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will not
> > be
> > > able
> > > > > to get the true voltage when it is above 3.0V, but knowing
> > that it is
> > > > > above 3.0V is good enough for me.
> > > > >
> > > > > --- In m...@yahoogroups.com
> > > ,
> > > > > Hendrik wrote:
> > > > > >
> > > > > > For my application I use a similar setup, dividing the 3.6V
> > > supply by
> > > > > > two 100K resistors (which effectively uses far less power
> > than
> > > using two
> > > > > > 1K resistors obviously and I'm not using a triode or
> > anything,
> > > just the
> > > > > > plain voltage divider), and using the internal 2.5V
> > reference of the
> > > > > > MSP430. A charged battery should thus give a measurement of
> > > 1.8V. When
> > > > > > measuring I got very strange values, but as far as I can
> > > remember I had
> > > > > > to changes the number of samples to be taken to a higher
> > number
> > > to get
> > > > > > stable results.
> > > > > >
> > > > > > Take a look at the example sources provided with the
> > > MSP430F22xx. The
> > > > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > > > > >
> > > > > > ADC10DTC1 =3D 0x040; // 64 conversions
> > > > > >
> > > > > > At the moment I cannot lookup the number of conversions I
> > used,
> > > but a
> > > > > > low value also yielded in inaccurate readings.
> > > > > >
> > > > > > Regards,
> > > > > > Hendrik
> > > > > >
> > > > > >
> > > > > >
> > > > > > =C3=A5=EF=BF=BD=C2=B4=C3=A6=EF=BF=BD=C2=A9=C3=A6=C2=B7=C2=B3 wr=
ote:
> > > > > > > Hi all:
> > > > > > >
> > > > > > > We are using MSP430F2272 and CC1101 to a low power
> > consumption
> > > > > solution, and
> > > > > > > want to measuring the voltage of the power supply battary,
> > which
> > > > > is 3.6V
> > > > > > > when full, and have to change it when belows 2.3V.
> > > > > > >
> > > > > > > And now we are measuring it by a method discribed as the
> > > > > following, but have
> > > > > > > some problems:
> > > > > > >
> > > > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with
> > it,
> > > > > because the
> > > > > > > AD will always 1023. we connect two resistances in
> > series(one 2K
> > > > > and another
> > > > > > > 1K), and open or close the current by a PNP CMOS triode,
> > which is
> > > > > controled
> > > > > > > by a GPIO port(P3.6), and measuring the voltage by A7
> > channel.
> > > > > > >
> > > > > > > When I want to measuring the voltage, first open the CMOS
> > > triode, and
> > > > > > > measuring it by the A7, when finish I close the triode to
> > save
> > > the
> > > > > power.
> > > > > > >
> > > > > > > The problem is: when the two resistances is 2K and 1K, the
> > VCC is
> > > > > 3.6V, and
> > > > > > > the real voltage between R1 and R2 is about 0.9v(I
> > measured by
> > > > > > > oscilloscope), and measued 0.9V by the program. But after
> > we
> > > > > changed R1 and
> > > > > > > R2 to 200K and 100K, which will save more power, and the
> > real
> > > voltage
> > > > > > > between R1 and R2 is about 0.9v too, but it isn't correct
> > by the
> > > > > program,
> > > > > > > which is about 1.2V. When I closed the triode, the voltage
> > is
> > > 0.3V by
> > > > > > > program but the real is 0V.
> > > > > > >
> > > > > > > Has anyone encountered with this strange problem? and can
> > someone
> > > > > provide a
> > > > > > > reference circurt to measuring the voltage of the supply
> > battary?
> > > > > please
> > > > > > > give me some propose, thanks in advance:)
> > > > > > >
> > > > > > > Vcc
> > > > > > > |
> > > > > > > -||-----P3.6
> > > > > > > |
> > > > > > > R1
> > > > > > > |
> > > > > > > =C3=83=C2=A2=C3=A2=EF=BF=BD=C2=AC ------P3.7(A7)
> > > > > > > |
> > > > > > > R2
> > > > > > > |
> > > > > > > ---
> > > > > > > -(GND)
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > > >
> > > >
> > >
> > >
> >
> >------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Bart Oegema - Aug 24 13:14:02 2009

Ignoring the fact that this is best done internally like has already
been mentioned, isn't the sampling rate the main issue? Even with a
high input impedance, given enough sample time to charge the internal
capacitance during sampling, the ADC should give consistent readings.

I'm not familiar with the 430F2272, but the 430Fx1xx family data sheet
provides a way to calculate the minimum sampling time given an
external impedance (p 17-9 of slau049f, if anyone finds this thread in
their searching later). I expect there's probably similar calculations
for other device families.

Or, if the calculated minimum sample time is too long for an
application, using an op-amp buffer like Augusto just suggested allows
for faster sample rates.

Correct me if I'm wrong, anyone.

- Bart
> higher sampling time.

On Mon, Aug 24, 2009 at 9:25 AM, Augusto Einsfeldt wrote:
> Hendrik,
> When the source impedance is high the reading will result in error due to
> the
> interaction with the ADC's input impedance.
> In order to not add erros the source's impedance must be at least 2^(n+1)
> lower
> than the ADC's impedance (n is ADC's number of bits).
> For example the F1611's data sheets suggest Rs equal or less than 400ohms
> when
> using the fastest possible conversion. It can be higher with a proportion=
aly
> higher sampling time.
> Of course, the internal MUX ON resistance must be accounted, too.
> This is why a simple resistor divider cannot be used in the ADC's input
> unless it
> is very low impedance. The solution is to use an operational amplifier as
> buffer.
> -Augusto
>
> On Seg 24/08/09 12:58 , Hendrik c...@yahoo.com sent:
>
>> Wow, I hijacked a topic with just a short question as a follow-up to
>> an
>> answer, just to hear if it wouldn't hurt to use an input voltage
>> above
>> the reference voltage and everyone is on top of me all of a sudden
>> :S ?!@
>> I know the input range is specified between 0 and VCC but the sheet
>> also
>> says that you only get valid results if the voltage is in range of
>> the
>> reference voltage. I don't think it's a stupid question to ask what
>> happens if the input voltage for the ADC higher than the reference
>> voltage (but indeed lower than VCC), in terms of 'damaging' to the
>> ADC.
>> Anyway, it was just a simple sub-question. The topic starter's
>> question
>> was about misreading the results and my answer was that he maybe
>> didn't
>> take enough samples to get a stable result, because I experienced
>> the
>> same misreading using relatively high resistor values.
>> Thanks for the A11 tip old_cow_yellow, I did not know that (and I
>> have
>> to use a pin not connected to A11).
>> Regards,
>> Hendrik
>> tintronic wrote:
>> >
>> >
>> > Haven't you yet got the hint to RTFM prior to asking questions?
>> > The input voltage range is a parameter that has to be described in
>> the
>> > Datasheet, just like any other voltage characteristic.
>> > The answer is right where it should be: look for the MSP430F2272
>> > datasheet (not User Guide), search for the chapter descibing the
>> MSP
>> > Electric Characteristics and then the page that descibes the ADC
>> input
>> > range.
>> >
>> > Michael K.
>> >
>> > --- In m...@yahoogroups.com ,
>> > Hendrik wrote:
>> > >
>> > > old_cow_yellow: so you're saying that it is not damaging to the
>> ADC
>> > > supplying a 3.6V source when using the internal 1.5V/2.5V
>> reference?
>> > >
>> > > old_cow_yellow wrote:
>> > > >
>> > > > If it were me, I would use analog channel 11 (0x0B), which is
>> > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
>> switch
>> > are
>> > > > all built-in and automatically enabled when I select A11.
>> > > >
>> > > > I would also use internal 1.5V reference, not internal 2.5V
>> > reference.
>> > > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference
>> is no
>> > > > longer 2.5V. (The 1.5V reference is still good when down to
>> > Vcc=3D2.2V.)
>> > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will not
>> be
>> > able
>> > > > to get the true voltage when it is above 3.0V, but knowing
>> that it is
>> > > > above 3.0V is good enough for me.
>> > > >
>> > > > --- In m...@yahoogroups.com
>> > ,
>> > > > Hendrik wrote:
>> > > > >
>> > > > > For my application I use a similar setup, dividing the 3.6V
>> > supply by
>> > > > > two 100K resistors (which effectively uses far less power
>> than
>> > using two
>> > > > > 1K resistors obviously and I'm not using a triode or
>> anything,
>> > just the
>> > > > > plain voltage divider), and using the internal 2.5V
>> reference of the
>> > > > > MSP430. A charged battery should thus give a measurement of
>> > 1.8V. When
>> > > > > measuring I got very strange values, but as far as I can
>> > remember I had
>> > > > > to changes the number of samples to be taken to a higher
>> number
>> > to get
>> > > > > stable results.
>> > > > >
>> > > > > Take a look at the example sources provided with the
>> > MSP430F22xx. The
>> > > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
>> > > > >
>> > > > > ADC10DTC1 =3D 0x040; // 64 conversions
>> > > > >
>> > > > > At the moment I cannot lookup the number of conversions I
>> used,
>> > but a
>> > > > > low value also yielded in inaccurate readings.
>> > > > >
>> > > > > Regards,
>> > > > > Hendrik
>> > > > >
>> > > > >
>> > > > >
>> > > > > =C3=A5=EF=BF=BD=C2=B4=C3=A6=EF=BF=BD=C2=A9=C3=A6=C2=B7=C2=B3 wro=
te:
>> > > > > > Hi all:
>> > > > > >
>> > > > > > We are using MSP430F2272 and CC1101 to a low power
>> consumption
>> > > > solution, and
>> > > > > > want to measuring the voltage of the power supply battary,
>> which
>> > > > is 3.6V
>> > > > > > when full, and have to change it when belows 2.3V.
>> > > > > >
>> > > > > > And now we are measuring it by a method discribed as the
>> > > > following, but have
>> > > > > > some problems:
>> > > > > >
>> > > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with
>> it,
>> > > > because the
>> > > > > > AD will always 1023. we connect two resistances in
>> series(one 2K
>> > > > and another
>> > > > > > 1K), and open or close the current by a PNP CMOS triode,
>> which is
>> > > > controled
>> > > > > > by a GPIO port(P3.6), and measuring the voltage by A7
>> channel.
>> > > > > >
>> > > > > > When I want to measuring the voltage, first open the CMOS
>> > triode, and
>> > > > > > measuring it by the A7, when finish I close the triode to
>> save
>> > the
>> > > > power.
>> > > > > >
>> > > > > > The problem is: when the two resistances is 2K and 1K, the
>> VCC is
>> > > > 3.6V, and
>> > > > > > the real voltage between R1 and R2 is about 0.9v(I
>> measured by
>> > > > > > oscilloscope), and measued 0.9V by the program. But after
>> we
>> > > > changed R1 and
>> > > > > > R2 to 200K and 100K, which will save more power, and the
>> real
>> > voltage
>> > > > > > between R1 and R2 is about 0.9v too, but it isn't correct
>> by the
>> > > > program,
>> > > > > > which is about 1.2V. When I closed the triode, the voltage
>> is
>> > 0.3V by
>> > > > > > program but the real is 0V.
>> > > > > >
>> > > > > > Has anyone encountered with this strange problem? and can
>> someone
>> > > > provide a
>> > > > > > reference circurt to measuring the voltage of the supply
>> battary?
>> > > > please
>> > > > > > give me some propose, thanks in advance:)
>> > > > > >
>> > > > > > Vcc
>> > > > > > |
>> > > > > > -||-----P3.6
>> > > > > > |
>> > > > > > R1
>> > > > > > |
>> > > > > > =C3=83=C2=A2=C3=A2=EF=BF=BD=C2=AC ------P3.7(A7)
>> > > > > > |
>> > > > > > R2
>> > > > > > |
>> > > > > > ---
>> > > > > > -(GND)
>> > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> > >
>> >
>> >
>>
>>=20
------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 13:39:26 2009

Of course this whole thread just goes to highlight the fact that you
cannot simply step into embedded systems design and start writing code,
or designing systems without any hardware knowledge, as many of the
posters here seem to think you can. Just hook up a sensor to this pin
down load that app note, cut and paste that piece of code, get some free
stuff from the news groups along the way and there we are with a
gigabuck killer app.

Al

Bart Oegema wrote:
> Ignoring the fact that this is best done internally like has already
> been mentioned, isn't the sampling rate the main issue? Even with a
> high input impedance, given enough sample time to charge the internal
> capacitance during sampling, the ADC should give consistent readings.
>
> I'm not familiar with the 430F2272, but the 430Fx1xx family data sheet
> provides a way to calculate the minimum sampling time given an
> external impedance (p 17-9 of slau049f, if anyone finds this thread in
> their searching later). I expect there's probably similar calculations
> for other device families.
>
> Or, if the calculated minimum sample time is too long for an
> application, using an op-amp buffer like Augusto just suggested allows
> for faster sample rates.
>
> Correct me if I'm wrong, anyone.
>
> - Bart
>> higher sampling time.
>
> On Mon, Aug 24, 2009 at 9:25 AM, Augusto Einsfeldt wrote:
>>
>> Hendrik,
>> When the source impedance is high the reading will result in error due to
>> the
>> interaction with the ADC's input impedance.
>> In order to not add erros the source's impedance must be at least 2^(n+1)
>> lower
>> than the ADC's impedance (n is ADC's number of bits).
>> For example the F1611's data sheets suggest Rs equal or less than 400ohms
>> when
>> using the fastest possible conversion. It can be higher with a proportionaly
>> higher sampling time.
>> Of course, the internal MUX ON resistance must be accounted, too.
>> This is why a simple resistor divider cannot be used in the ADC's input
>> unless it
>> is very low impedance. The solution is to use an operational amplifier as
>> buffer.
>> -Augusto
>>
>> On Seg 24/08/09 12:58 , Hendrik c...@yahoo.com sent:
>>
>>> Wow, I hijacked a topic with just a short question as a follow-up to
>>> an
>>> answer, just to hear if it wouldn't hurt to use an input voltage
>>> above
>>> the reference voltage and everyone is on top of me all of a sudden
>>> :S ?!@
>>> I know the input range is specified between 0 and VCC but the sheet
>>> also
>>> says that you only get valid results if the voltage is in range of
>>> the
>>> reference voltage. I don't think it's a stupid question to ask what
>>> happens if the input voltage for the ADC higher than the reference
>>> voltage (but indeed lower than VCC), in terms of 'damaging' to the
>>> ADC.
>>> Anyway, it was just a simple sub-question. The topic starter's
>>> question
>>> was about misreading the results and my answer was that he maybe
>>> didn't
>>> take enough samples to get a stable result, because I experienced
>>> the
>>> same misreading using relatively high resistor values.
>>> Thanks for the A11 tip old_cow_yellow, I did not know that (and I
>>> have
>>> to use a pin not connected to A11).
>>> Regards,
>>> Hendrik
>>> tintronic wrote:
>>>>
>>>> Haven't you yet got the hint to RTFM prior to asking questions?
>>>> The input voltage range is a parameter that has to be described in
>>> the
>>>> Datasheet, just like any other voltage characteristic.
>>>> The answer is right where it should be: look for the MSP430F2272
>>>> datasheet (not User Guide), search for the chapter descibing the
>>> MSP
>>>> Electric Characteristics and then the page that descibes the ADC
>>> input
>>>> range.
>>>>
>>>> Michael K.
>>>>
>>>> --- In m...@yahoogroups.com ,
>>>> Hendrik wrote:
>>>>> old_cow_yellow: so you're saying that it is not damaging to the
>>> ADC
>>>>> supplying a 3.6V source when using the internal 1.5V/2.5V
>>> reference?
>>>>> old_cow_yellow wrote:
>>>>>> If it were me, I would use analog channel 11 (0x0B), which is
>>>>>> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
>>> switch
>>>> are
>>>>>> all built-in and automatically enabled when I select A11.
>>>>>>
>>>>>> I would also use internal 1.5V reference, not internal 2.5V
>>>> reference.
>>>>>> My reason is, when Vcc drops below 2.8V, the "2.5V" reference
>>> is no
>>>>>> longer 2.5V. (The 1.5V reference is still good when down to
>>>> Vcc=2.2V.)
>>>>>> When Vcc is above 3.0V, ADC will be saturated. Thus I will not
>>> be
>>>> able
>>>>>> to get the true voltage when it is above 3.0V, but knowing
>>> that it is
>>>>>> above 3.0V is good enough for me.
>>>>>>
>>>>>> --- In m...@yahoogroups.com
>>>> ,
>>>>>> Hendrik wrote:
>>>>>>> For my application I use a similar setup, dividing the 3.6V
>>>> supply by
>>>>>>> two 100K resistors (which effectively uses far less power
>>> than
>>>> using two
>>>>>>> 1K resistors obviously and I'm not using a triode or
>>> anything,
>>>> just the
>>>>>>> plain voltage divider), and using the internal 2.5V
>>> reference of the
>>>>>>> MSP430. A charged battery should thus give a measurement of
>>>> 1.8V. When
>>>>>>> measuring I got very strange values, but as far as I can
>>>> remember I had
>>>>>>> to changes the number of samples to be taken to a higher
>>> number
>>>> to get
>>>>>>> stable results.
>>>>>>>
>>>>>>> Take a look at the example sources provided with the
>>>> MSP430F22xx. The
>>>>>>> file 'msp430x22x4_adc10_19.c might lead to this setting:
>>>>>>>
>>>>>>> ADC10DTC1 = 0x040; // 64 conversions
>>>>>>>
>>>>>>> At the moment I cannot lookup the number of conversions I
>>> used,
>>>> but a
>>>>>>> low value also yielded in inaccurate readings.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Hendrik
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> å�´æ�©æ·³ wrote:
>>>>>>>> Hi all:
>>>>>>>>
>>>>>>>> We are using MSP430F2272 and CC1101 to a low power
>>> consumption
>>>>>> solution, and
>>>>>>>> want to measuring the voltage of the power supply battary,
>>> which
>>>>>> is 3.6V
>>>>>>>> when full, and have to change it when belows 2.3V.
>>>>>>>>
>>>>>>>> And now we are measuring it by a method discribed as the
>>>>>> following, but have
>>>>>>>> some problems:
>>>>>>>>
>>>>>>>> As MSP430 Vref is 2.5v, so we can't measuring the VCC with
>>> it,
>>>>>> because the
>>>>>>>> AD will always 1023. we connect two resistances in
>>> series(one 2K
>>>>>> and another
>>>>>>>> 1K), and open or close the current by a PNP CMOS triode,
>>> which is
>>>>>> controled
>>>>>>>> by a GPIO port(P3.6), and measuring the voltage by A7
>>> channel.
>>>>>>>> When I want to measuring the voltage, first open the CMOS
>>>> triode, and
>>>>>>>> measuring it by the A7, when finish I close the triode to
>>> save
>>>> the
>>>>>> power.
>>>>>>>> The problem is: when the two resistances is 2K and 1K, the
>>> VCC is
>>>>>> 3.6V, and
>>>>>>>> the real voltage between R1 and R2 is about 0.9v(I
>>> measured by
>>>>>>>> oscilloscope), and measued 0.9V by the program. But after
>>> we
>>>>>> changed R1 and
>>>>>>>> R2 to 200K and 100K, which will save more power, and the
>>> real
>>>> voltage
>>>>>>>> between R1 and R2 is about 0.9v too, but it isn't correct
>>> by the
>>>>>> program,
>>>>>>>> which is about 1.2V. When I closed the triode, the voltage
>>> is
>>>> 0.3V by
>>>>>>>> program but the real is 0V.
>>>>>>>>
>>>>>>>> Has anyone encountered with this strange problem? and can
>>> someone
>>>>>> provide a
>>>>>>>> reference circurt to measuring the voltage of the supply
>>> battary?
>>>>>> please
>>>>>>>> give me some propose, thanks in advance:)
>>>>>>>>
>>>>>>>> Vcc
>>>>>>>> |
>>>>>>>> -||-----P3.6
>>>>>>>> |
>>>>>>>> R1
>>>>>>>> |
>>>>>>>> Ã¢â�¬ ------P3.7(A7)
>>>>>>>> |
>>>>>>>> R2
>>>>>>>> |
>>>>>>>> ---
>>>>>>>> -(GND)
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>> ------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Augusto Einsfeldt - Aug 24 14:08:39 2009

Actualy, not. The leakage and other current eaters act like a resistor betw=
een the=20
input pin and the VSS and this would serve as a voltage divider with the so=
urce's=20
resistence (impedance). And this leakage, as much as the source's impedance=
, can=20
vary with temperature, supply voltage and semiconductor fabrication process=
.
Thinking just about capacitor charge would mean a perfect ADC input with in=
finite=20
impedance.

But if we enter too deeply in this kind of subject we fall in the same spot=
Al did=20
try to make clear: electronics design is not just cut & paste things. Deman=
ds a=20
lot of reading, testing and learning.

-Augusto
On Seg 24/08/09 13:44 , Bart Oegema b...@gmail.com sent:
> Ignoring the fact that this is best done internally like has already
> been mentioned, isn't the sampling rate the main issue? Even with a
> high input impedance, given enough sample time to charge the
> internal
> capacitance during sampling, the ADC should give consistent
> readings.
> I'm not familiar with the 430F2272, but the 430Fx1xx family data
> sheet
> provides a way to calculate the minimum sampling time given an
> external impedance (p 17-9 of slau049f, if anyone finds this thread
> in
> their searching later). I expect there's probably similar
> calculations
> for other device families.
> Or, if the calculated minimum sample time is too long for an
> application, using an op-amp buffer like Augusto just suggested
> allows
> for faster sample rates.
> Correct me if I'm wrong, anyone.
> - Bart
> > higher sampling time.
> On Mon, Aug 24, 2009 at 9:25 AM, Augusto Einsfeldt wrote:
> >
> >
> > Hendrik,
> > When the source impedance is high the reading will result in error
> due to
> > the
> > interaction with the ADC's input impedance.
> > In order to not add erros the source's impedance must be at least
> 2^(n+1)
> > lower
> > than the ADC's impedance (n is ADC's number of bits).
> > For example the F1611's data sheets suggest Rs equal or less than
> 400ohms
> > when
> > using the fastest possible conversion. It can be higher with a
> proportionaly
> > higher sampling time.
> > Of course, the internal MUX ON resistance must be accounted, too.
> > This is why a simple resistor divider cannot be used in the ADC's
> input
> > unless it
> > is very low impedance. The solution is to use an operational
> amplifier as
> > buffer.
> > -Augusto
> >
> > On Seg 24/08/09 12:58 , Hendrik c...@yahoo.com sent:
> >
> >> Wow, I hijacked a topic with just a short question as a follow-up
> to
> >> an
> >> answer, just to hear if it wouldn't hurt to use an input voltage
> >> above
> >> the reference voltage and everyone is on top of me all of a
> sudden
> >> :S ?!@
> >> I know the input range is specified between 0 and VCC but the
> sheet
> >> also
> >> says that you only get valid results if the voltage is in range
> of
> >> the
> >> reference voltage. I don't think it's a stupid question to ask
> what
> >> happens if the input voltage for the ADC higher than the
> reference
> >> voltage (but indeed lower than VCC), in terms of 'damaging' to
> the
> >> ADC.
> >> Anyway, it was just a simple sub-question. The topic starter's
> >> question
> >> was about misreading the results and my answer was that he maybe
> >> didn't
> >> take enough samples to get a stable result, because I experienced
> >> the
> >> same misreading using relatively high resistor values.
> >> Thanks for the A11 tip old_cow_yellow, I did not know that (and I
> >> have
> >> to use a pin not connected to A11).
> >> Regards,
> >> Hendrik
> >> tintronic wrote:
> >> >
> >> >
> >> > Haven't you yet got the hint to RTFM prior to asking questions?
> >> > The input voltage range is a parameter that has to be described
> in
> >> the
> >> > Datasheet, just like any other voltage characteristic.
> >> > The answer is right where it should be: look for the
> MSP430F2272
> >> > datasheet (not User Guide), search for the chapter descibing
> the
> >> MSP
> >> > Electric Characteristics and then the page that descibes the
> ADC
> >> input
> >> > range.
> >> >
> >> > Michael K.
> >> >
> >> > --- In m...@yahoogroups.com ,
> >> > Hendrik wrote:
> >> > >
> >> > > old_cow_yellow: so you're saying that it is not damaging to
> the
> >> ADC
> >> > > supplying a 3.6V source when using the internal 1.5V/2.5V
> >> reference?
> >> > >
> >> > > old_cow_yellow wrote:
> >> > > >
> >> > > > If it were me, I would use analog channel 11 (0x0B), which
> is
> >> > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
> >> switch
> >> > are
> >> > > > all built-in and automatically enabled when I select A11.
> >> > > >
> >> > > > I would also use internal 1.5V reference, not internal 2.5V
> >> > reference.
> >> > > > My reason is, when Vcc drops below 2.8V, the "2.5V"
> reference
> >> is no
> >> > > > longer 2.5V. (The 1.5V reference is still good when down to
> >> > Vcc=3D2.2V.)
> >> > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will
> not
> >> be
> >> > able
> >> > > > to get the true voltage when it is above 3.0V, but knowing
> >> that it is
> >> > > > above 3.0V is good enough for me.
> >> > > >
> >> > > > --- In m...@yahoogroups.com
> >> > ,
> >> > > > Hendrik wrote:
> >> > > > >
> >> > > > > For my application I use a similar setup, dividing the
> 3.6V
> >> > supply by
> >> > > > > two 100K resistors (which effectively uses far less power
> >> than
> >> > using two
> >> > > > > 1K resistors obviously and I'm not using a triode or
> >> anything,
> >> > just the
> >> > > > > plain voltage divider), and using the internal 2.5V
> >> reference of the
> >> > > > > MSP430. A charged battery should thus give a measurement
> of
> >> > 1.8V. When
> >> > > > > measuring I got very strange values, but as far as I can
> >> > remember I had
> >> > > > > to changes the number of samples to be taken to a higher
> >> number
> >> > to get
> >> > > > > stable results.
> >> > > > >
> >> > > > > Take a look at the example sources provided with the
> >> > MSP430F22xx. The
> >> > > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> >> > > > >
> >> > > > > ADC10DTC1 =3D 0x040; // 64 conversions
> >> > > > >
> >> > > > > At the moment I cannot lookup the number of conversions I
> >> used,
> >> > but a
> >> > > > > low value also yielded in inaccurate readings.
> >> > > > >
> >> > > > > Regards,
> >> > > > > Hendrik
> >> > > > >
> >> > > > >
> >> > > > >
> >> > > > > =C3=A5=EF=BF=BD=C2=B4=C3=A6=EF=BF=BD=C2=A9=C3=A6=C2=B7=C2=B3 w=
rote:
> >> > > > > > Hi all:
> >> > > > > >
> >> > > > > > We are using MSP430F2272 and CC1101 to a low power
> >> consumption
> >> > > > solution, and
> >> > > > > > want to measuring the voltage of the power supply
> battary,
> >> which
> >> > > > is 3.6V
> >> > > > > > when full, and have to change it when belows 2.3V.
> >> > > > > >
> >> > > > > > And now we are measuring it by a method discribed as
> the
> >> > > > following, but have
> >> > > > > > some problems:
> >> > > > > >
> >> > > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC
> with
> >> it,
> >> > > > because the
> >> > > > > > AD will always 1023. we connect two resistances in
> >> series(one 2K
> >> > > > and another
> >> > > > > > 1K), and open or close the current by a PNP CMOS
> triode,
> >> which is
> >> > > > controled
> >> > > > > > by a GPIO port(P3.6), and measuring the voltage by A7
> >> channel.
> >> > > > > >
> >> > > > > > When I want to measuring the voltage, first open the
> CMOS
> >> > triode, and
> >> > > > > > measuring it by the A7, when finish I close the triode
> to
> >> save
> >> > the
> >> > > > power.
> >> > > > > >
> >> > > > > > The problem is: when the two resistances is 2K and 1K,
> the
> >> VCC is
> >> > > > 3.6V, and
> >> > > > > > the real voltage between R1 and R2 is about 0.9v(I
> >> measured by
> >> > > > > > oscilloscope), and measued 0.9V by the program. But
> after
> >> we
> >> > > > changed R1 and
> >> > > > > > R2 to 200K and 100K, which will save more power, and
> the
> >> real
> >> > voltage
> >> > > > > > between R1 and R2 is about 0.9v too, but it isn't
> correct
> >> by the
> >> > > > program,
> >> > > > > > which is about 1.2V. When I closed the triode, the
> voltage
> >> is
> >> > 0.3V by
> >> > > > > > program but the real is 0V.
> >> > > > > >
> >> > > > > > Has anyone encountered with this strange problem? and
> can
> >> someone
> >> > > > provide a
> >> > > > > > reference circurt to measuring the voltage of the
> supply
> >> battary?
> >> > > > please
> >> > > > > > give me some propose, thanks in advance:)
> >> > > > > >
> >> > > > > > Vcc
> >> > > > > > |
> >> > > > > > -||-----P3.6
> >> > > > > > |
> >> > > > > > R1
> >> > > > > > |
> >> > > > > > =C3=83=C2=A2=C3=A2=EF=BF=BD=C2=AC ------P3.7(A7)
> >> > > > > > |
> >> > > > > > R2
> >> > > > > > |
> >> > > > > > ---
> >> > > > > > -(GND)
> >> > > > > >
> >> > > > > >
> >> > > > >
> >> > > >
> >> > > >
> >> > >
> >> >
> >> >
> >>
> >>
> >
> >=20
>=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
>=20

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 15:51:04 2009

Hendrik,
I took a lot of time writing this, so I hope you read it fully.

> Wow, I hijacked a topic with just a short question as a follow-up
> to an answer, just to hear if it wouldn't hurt to use an input
> voltage above the reference voltage and everyone is on top of me
> all of a sudden :S ?!@
First, any follow-up questions should involve some follow-up reading before=
posting the follow-up question.

Second, let's see the answer and the follow-up question:
The answer:
> > > old_cow_yellow wrote:
> > > > If it were me, I would use analog channel 11 (0x0B), which is
> > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
> > > > switch are all built-in and automatically enabled when I
> > > > select A11.
> > > > I would also use internal 1.5V reference, not internal 2.5V
> > > > reference.
> > > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference
> > > > is no longer 2.5V. (The 1.5V reference is still good when
> > > > down to Vcc=3D2.2V.)
> > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will
> > > > not be able to get the true voltage when it is above 3.0V,
> > > > but knowing that it is above 3.0V is good enough for me.

The follow-up question:
> > > old_cow_yellow: so you're saying that it is not damaging to the
> > > ADC supplying a 3.6V source when using the internal 1.5V/2.5V
> > > reference?

OCY didn't say that at all. Now I'm not even sure what you mean by "supplyi=
ng 3.6V source". That post only shows that you didn't even read OCY post tw=
ice. OCY presented you with VA11 =3D Vcc/2, which based on the other data h=
e provided is 1.1 to 1.8V.

> I know the input range is specified between 0 and VCC but the sheet
> also says that you only get valid results if the voltage is in
> range of the reference voltage.
Your post was based on your conclusions of what OCY said, not on the datash=
eet or what you now say you knew.

> I don't think it's a stupid question to ask what happens if the
> input voltage for the ADC higher than the reference voltage (but
> indeed lower than VCC), in terms of 'damaging' to the ADC.
No it's not a supid question, but you didn't ask that, did you?

Take the time to elaborate your question propperly if you want people to ta=
ke time to answer it in the same way. That way you write what you know, on =
what base (quoting the source: document name/code and page), and where your=
question lies, because you shouldn't take the word of anybody anyway if he=
doesn't provide some ground to his answer.=20

If you had asked the question like this:
"The msp430f2272 datasheet on page 46 specifies the analog input voltage ra=
nge to be 0 to Vcc, but it also specifies that, and I quote: 'The analog in=
put voltage range must be within the selected reference voltage range VR+ t=
o VR- for valid conversion results'. So I'm confused if this means if the A=
DC can be damaged or not if the applied voltage is outside VR+ to VR- but w=
ithin 0 to Vcc".

Your problem is, in fact, no other than interpreting the datasheet. In that=
case, I (or somebody else) would have replied:

If voltages outside the range VR+ to VR- were to produce damage to the ADC,=
VAx would be specified to be VR- to VR+ and not 0 to Vcc. You can conclude=
from the datasheet that:
1) You can apply 0 to Vcc to any VAx terminal
2) Only voltages in the range VR- to VR+ will provide valid conversion resu=
lts.
3) You can't predict for sure, based on this information, what the ADC10 re=
sult will be if you apply voltages outside the range VR- to VR+.

So you go to the User's Guid ADC10 chapter and search there. You will find =
on document slau144e "MSP430x2xx User's Guide" on chapter 24 page 4 (page58=
6) that (I quote):
"The digital output (NADC) is full scale (03FFh) when the input signal is e=
qual to or higher than VR+, and zero when the input signal is equal to or l=
ower than VR−."

So there you have it. It was all in the two most important documents and yo=
u could have easily found it out by yourself, or at least post a proper que=
stion.

All you had to do was just taken the time to write what you knew, confirm w=
hat you were basing your assumptions on, and what your real question was ba=
sed on that.

So don't you feel unjustly treaten if I tell you to RTFM.

Michael K.

--- In m...@yahoogroups.com, Hendrik wrote:
>
> Wow, I hijacked a topic with just a short question as a follow-up to an=20
> answer, just to hear if it wouldn't hurt to use an input voltage above=20
> the reference voltage and everyone is on top of me all of a sudden :S ?!@
>=20
> I know the input range is specified between 0 and VCC but the sheet also=
=20
> says that you only get valid results if the voltage is in range of the=20
> reference voltage. I don't think it's a stupid question to ask what=20
> happens if the input voltage for the ADC higher than the reference=20
> voltage (but indeed lower than VCC), in terms of 'damaging' to the ADC.
>=20
> Anyway, it was just a simple sub-question. The topic starter's question=20
> was about misreading the results and my answer was that he maybe didn't=20
> take enough samples to get a stable result, because I experienced the=20
> same misreading using relatively high resistor values.
>=20
> Thanks for the A11 tip old_cow_yellow, I did not know that (and I have=20
> to use a pin not connected to A11).
>=20
> Regards,
> Hendrik
>=20
> tintronic wrote:
> >=20=20
> >
> > Haven't you yet got the hint to RTFM prior to asking questions?
> > The input voltage range is a parameter that has to be described in the=
=20
> > Datasheet, just like any other voltage characteristic.
> > The answer is right where it should be: look for the MSP430F2272=20
> > datasheet (not User Guide), search for the chapter descibing the MSP=20
> > Electric Characteristics and then the page that descibes the ADC input=
=20
> > range.
> >
> > Michael K.
> >
> > --- In m...@yahoogroups.com ,=20
> > Hendrik wrote:
> > >
> > > old_cow_yellow: so you're saying that it is not damaging to the ADC
> > > supplying a 3.6V source when using the internal 1.5V/2.5V reference?
> > >
> > > old_cow_yellow wrote:
> > > >
> > > > If it were me, I would use analog channel 11 (0x0B), which is
> > > > (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch=
=20
> > are
> > > > all built-in and automatically enabled when I select A11.
> > > >
> > > > I would also use internal 1.5V reference, not internal 2.5V=20
> > reference.
> > > > My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
> > > > longer 2.5V. (The 1.5V reference is still good when down to=20
> > Vcc=3D2.2V.)
> > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will not be=20
> > able
> > > > to get the true voltage when it is above 3.0V, but knowing that it =
is
> > > > above 3.0V is good enough for me.
> > > >
> > > > --- In m...@yahoogroups.com =20
> > ,
> > > > Hendrik wrote:
> > > > >
> > > > > For my application I use a similar setup, dividing the 3.6V=20
> > supply by
> > > > > two 100K resistors (which effectively uses far less power than=20
> > using two
> > > > > 1K resistors obviously and I'm not using a triode or anything,=20
> > just the
> > > > > plain voltage divider), and using the internal 2.5V reference of =
the
> > > > > MSP430. A charged battery should thus give a measurement of=20
> > 1.8V. When
> > > > > measuring I got very strange values, but as far as I can=20
> > remember I had
> > > > > to changes the number of samples to be taken to a higher number=20
> > to get
> > > > > stable results.
> > > > >
> > > > > Take a look at the example sources provided with the=20
> > MSP430F22xx. The
> > > > > file 'msp430x22x4_adc10_19.c might lead to this setting:
> > > > >
> > > > > ADC10DTC1 =3D 0x040; // 64 conversions
> > > > >
> > > > > At the moment I cannot lookup the number of conversions I used,=20
> > but a
> > > > > low value also yielded in inaccurate readings.
> > > > >
> > > > > Regards,
> > > > > Hendrik
> > > > >
> > > > >
> > > > >
> > > > > =E5�=B4=E6�=A9=E6=B7=B3 wrote:
> > > > > > Hi all:
> > > > > >
> > > > > > We are using MSP430F2272 and CC1101 to a low power consumption
> > > > solution, and
> > > > > > want to measuring the voltage of the power supply battary, whic=
h
> > > > is 3.6V
> > > > > > when full, and have to change it when belows 2.3V.
> > > > > >
> > > > > > And now we are measuring it by a method discribed as the
> > > > following, but have
> > > > > > some problems:
> > > > > >
> > > > > > As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
> > > > because the
> > > > > > AD will always 1023. we connect two resistances in series(one 2=
K
> > > > and another
> > > > > > 1K), and open or close the current by a PNP CMOS triode, which =
is
> > > > controled
> > > > > > by a GPIO port(P3.6), and measuring the voltage by A7 channel.
> > > > > >
> > > > > > When I want to measuring the voltage, first open the CMOS=20
> > triode, and
> > > > > > measuring it by the A7, when finish I close the triode to save=
=20
> > the
> > > > power.
> > > > > >
> > > > > > The problem is: when the two resistances is 2K and 1K, the VCC =
is
> > > > 3.6V, and
> > > > > > the real voltage between R1 and R2 is about 0.9v(I measured by
> > > > > > oscilloscope), and measued 0.9V by the program. But after we
> > > > changed R1 and
> > > > > > R2 to 200K and 100K, which will save more power, and the real=20
> > voltage
> > > > > > between R1 and R2 is about 0.9v too, but it isn't correct by th=
e
> > > > program,
> > > > > > which is about 1.2V. When I closed the triode, the voltage is=20
> > 0.3V by
> > > > > > program but the real is 0V.
> > > > > >
> > > > > > Has anyone encountered with this strange problem? and can someo=
ne
> > > > provide a
> > > > > > reference circurt to measuring the voltage of the supply battar=
y?
> > > > please
> > > > > > give me some propose, thanks in advance:)
> > > > > >
> > > > > > Vcc
> > > > > > |
> > > > > > -||-----P3.6
> > > > > > |
> > > > > > R1
> > > > > > |
> > > > > > =C3=A2=E2�=AC ------P3.7(A7)
> > > > > > |
> > > > > > R2
> > > > > > |
> > > > > > ---
> > > > > > -(GND)
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
>

------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 15:58:37 2009

Wow Michael, and I used to get hate mail because people thought I was
too cruel!!

;@}

there's no such thing as too cruel, it's only varying degrees of kindness.

I'm no longer fat, merely anorexically challenged!!

Cheers

Al

tintronic wrote:
> Hendrik,
> I took a lot of time writing this, so I hope you read it fully.
>
>> Wow, I hijacked a topic with just a short question as a follow-up
>> to an answer, just to hear if it wouldn't hurt to use an input
>> voltage above the reference voltage and everyone is on top of me
>> all of a sudden :S ?!@
> First, any follow-up questions should involve some follow-up reading before posting the follow-up question.
>
> Second, let's see the answer and the follow-up question:
> The answer:
>>>> old_cow_yellow wrote:
>>>>> If it were me, I would use analog channel 11 (0x0B), which is
>>>>> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving
>>>>> switch are all built-in and automatically enabled when I
>>>>> select A11.
>>>>> I would also use internal 1.5V reference, not internal 2.5V
>>>>> reference.
>>>>> My reason is, when Vcc drops below 2.8V, the "2.5V" reference
>>>>> is no longer 2.5V. (The 1.5V reference is still good when
>>>>> down to Vcc=2.2V.)
>>>>> When Vcc is above 3.0V, ADC will be saturated. Thus I will
>>>>> not be able to get the true voltage when it is above 3.0V,
>>>>> but knowing that it is above 3.0V is good enough for me.
>
> The follow-up question:
>>>> old_cow_yellow: so you're saying that it is not damaging to the
>>>> ADC supplying a 3.6V source when using the internal 1.5V/2.5V
>>>> reference?
>
> OCY didn't say that at all. Now I'm not even sure what you mean by "supplying 3.6V source". That post only shows that you didn't even read OCY post twice. OCY presented you with VA11 = Vcc/2, which based on the other data he provided is 1.1 to 1.8V.
>
>> I know the input range is specified between 0 and VCC but the sheet
>> also says that you only get valid results if the voltage is in
>> range of the reference voltage.
> Your post was based on your conclusions of what OCY said, not on the datasheet or what you now say you knew.
>
>> I don't think it's a stupid question to ask what happens if the
>> input voltage for the ADC higher than the reference voltage (but
>> indeed lower than VCC), in terms of 'damaging' to the ADC.
> No it's not a supid question, but you didn't ask that, did you?
>
> Take the time to elaborate your question propperly if you want people to take time to answer it in the same way. That way you write what you know, on what base (quoting the source: document name/code and page), and where your question lies, because you shouldn't take the word of anybody anyway if he doesn't provide some ground to his answer.
>
> If you had asked the question like this:
> "The msp430f2272 datasheet on page 46 specifies the analog input voltage range to be 0 to Vcc, but it also specifies that, and I quote: 'The analog input voltage range must be within the selected reference voltage range VR+ to VR- for valid conversion results'. So I'm confused if this means if the ADC can be damaged or not if the applied voltage is outside VR+ to VR- but within 0 to Vcc".
>
> Your problem is, in fact, no other than interpreting the datasheet. In that case, I (or somebody else) would have replied:
>
> If voltages outside the range VR+ to VR- were to produce damage to the ADC, VAx would be specified to be VR- to VR+ and not 0 to Vcc. You can conclude from the datasheet that:
> 1) You can apply 0 to Vcc to any VAx terminal
> 2) Only voltages in the range VR- to VR+ will provide valid conversion results.
> 3) You can't predict for sure, based on this information, what the ADC10 result will be if you apply voltages outside the range VR- to VR+.
>
> So you go to the User's Guid ADC10 chapter and search there. You will find on document slau144e "MSP430x2xx User's Guide" on chapter 24 page 4 (page586) that (I quote):
> "The digital output (NADC) is full scale (03FFh) when the input signal is equal to or higher than VR+, and zero when the input signal is equal to or lower than VR−."
>
> So there you have it. It was all in the two most important documents and you could have easily found it out by yourself, or at least post a proper question.
>
> All you had to do was just taken the time to write what you knew, confirm what you were basing your assumptions on, and what your real question was based on that.
>
> So don't you feel unjustly treaten if I tell you to RTFM.
>
> Michael K.
>
> --- In m...@yahoogroups.com, Hendrik wrote:
>> Wow, I hijacked a topic with just a short question as a follow-up to an
>> answer, just to hear if it wouldn't hurt to use an input voltage above
>> the reference voltage and everyone is on top of me all of a sudden :S ?!@
>>
>> I know the input range is specified between 0 and VCC but the sheet also
>> says that you only get valid results if the voltage is in range of the
>> reference voltage. I don't think it's a stupid question to ask what
>> happens if the input voltage for the ADC higher than the reference
>> voltage (but indeed lower than VCC), in terms of 'damaging' to the ADC.
>>
>> Anyway, it was just a simple sub-question. The topic starter's question
>> was about misreading the results and my answer was that he maybe didn't
>> take enough samples to get a stable result, because I experienced the
>> same misreading using relatively high resistor values.
>>
>> Thanks for the A11 tip old_cow_yellow, I did not know that (and I have
>> to use a pin not connected to A11).
>>
>> Regards,
>> Hendrik
>>
>> tintronic wrote:
>>>
>>>
>>> Haven't you yet got the hint to RTFM prior to asking questions?
>>> The input voltage range is a parameter that has to be described in the
>>> Datasheet, just like any other voltage characteristic.
>>> The answer is right where it should be: look for the MSP430F2272
>>> datasheet (not User Guide), search for the chapter descibing the MSP
>>> Electric Characteristics and then the page that descibes the ADC input
>>> range.
>>>
>>> Michael K.
>>>
>>> --- In m...@yahoogroups.com ,
>>> Hendrik wrote:
>>>> old_cow_yellow: so you're saying that it is not damaging to the ADC
>>>> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
>>>>
>>>> old_cow_yellow wrote:
>>>>> If it were me, I would use analog channel 11 (0x0B), which is
>>>>> (Vcc-Vss)/2. The divide by 2 resistors and the power-saving switch
>>> are
>>>>> all built-in and automatically enabled when I select A11.
>>>>>
>>>>> I would also use internal 1.5V reference, not internal 2.5V
>>> reference.
>>>>> My reason is, when Vcc drops below 2.8V, the "2.5V" reference is no
>>>>> longer 2.5V. (The 1.5V reference is still good when down to
>>> Vcc=2.2V.)
>>>>> When Vcc is above 3.0V, ADC will be saturated. Thus I will not be
>>> able
>>>>> to get the true voltage when it is above 3.0V, but knowing that it is
>>>>> above 3.0V is good enough for me.
>>>>>
>>>>> --- In m...@yahoogroups.com
>>> ,
>>>>> Hendrik wrote:
>>>>>> For my application I use a similar setup, dividing the 3.6V
>>> supply by
>>>>>> two 100K resistors (which effectively uses far less power than
>>> using two
>>>>>> 1K resistors obviously and I'm not using a triode or anything,
>>> just the
>>>>>> plain voltage divider), and using the internal 2.5V reference of the
>>>>>> MSP430. A charged battery should thus give a measurement of
>>> 1.8V. When
>>>>>> measuring I got very strange values, but as far as I can
>>> remember I had
>>>>>> to changes the number of samples to be taken to a higher number
>>> to get
>>>>>> stable results.
>>>>>>
>>>>>> Take a look at the example sources provided with the
>>> MSP430F22xx. The
>>>>>> file 'msp430x22x4_adc10_19.c might lead to this setting:
>>>>>>
>>>>>> ADC10DTC1 = 0x040; // 64 conversions
>>>>>>
>>>>>> At the moment I cannot lookup the number of conversions I used,
>>> but a
>>>>>> low value also yielded in inaccurate readings.
>>>>>>
>>>>>> Regards,
>>>>>> Hendrik
>>>>>>
>>>>>>
>>>>>>
>>>>>> ��淳 wrote:
>>>>>>> Hi all:
>>>>>>>
>>>>>>> We are using MSP430F2272 and CC1101 to a low power consumption
>>>>> solution, and
>>>>>>> want to measuring the voltage of the power supply battary, which
>>>>> is 3.6V
>>>>>>> when full, and have to change it when belows 2.3V.
>>>>>>>
>>>>>>> And now we are measuring it by a method discribed as the
>>>>> following, but have
>>>>>>> some problems:
>>>>>>>
>>>>>>> As MSP430 Vref is 2.5v, so we can't measuring the VCC with it,
>>>>> because the
>>>>>>> AD will always 1023. we connect two resistances in series(one 2K
>>>>> and another
>>>>>>> 1K), and open or close the current by a PNP CMOS triode, which is
>>>>> controled
>>>>>>> by a GPIO port(P3.6), and measuring the voltage by A7 channel.
>>>>>>>
>>>>>>> When I want to measuring the voltage, first open the CMOS
>>> triode, and
>>>>>>> measuring it by the A7, when finish I close the triode to save
>>> the
>>>>> power.
>>>>>>> The problem is: when the two resistances is 2K and 1K, the VCC is
>>>>> 3.6V, and
>>>>>>> the real voltage between R1 and R2 is about 0.9v(I measured by
>>>>>>> oscilloscope), and measued 0.9V by the program. But after we
>>>>> changed R1 and
>>>>>>> R2 to 200K and 100K, which will save more power, and the real
>>> voltage
>>>>>>> between R1 and R2 is about 0.9v too, but it isn't correct by the
>>>>> program,
>>>>>>> which is about 1.2V. When I closed the triode, the voltage is
>>> 0.3V by
>>>>>>> program but the real is 0V.
>>>>>>>
>>>>>>> Has anyone encountered with this strange problem? and can someone
>>>>> provide a
>>>>>>> reference circurt to measuring the voltage of the supply battary?
>>>>> please
>>>>>>> give me some propose, thanks in advance:)
>>>>>>>
>>>>>>> Vcc
>>>>>>> |
>>>>>>> -||-----P3.6
>>>>>>> |
>>>>>>> R1
>>>>>>> |
>>>>>>> â�� ------P3.7(A7)
>>>>>>> |
>>>>>>> R2
>>>>>>> |
>>>>>>> ---
>>>>>>> -(GND)
>>>>>>>
>>>>>>>
>>>>>
>>>
> ------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 25 4:10:45 2009

Aargh, why do we keep going on and on about all this. It was not my
question/topic in the first place!

[OCY]
> > > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will
> > > > > not be able to get the true voltage when it is above 3.0V,
> > > > > but knowing that it is above 3.0V is good enough for me.
> > > > old_cow_yellow: so you're saying that it is not damaging to the
> > > > ADC supplying a 3.6V source when using the internal 1.5V/2.5V
> > > > reference?
> OCY didn't say that at all. Now I'm not even sure what you mean by
"supplying 3.6V source". That post only shows that you
> didn't even read OCY post twice. OCY presented you with VA11 = Vcc/2,
which based on the other data he provided is 1.1 to
> 1.8V.

Perhaps the 'so you're saying' is not the right phrase here. He says
that a voltage above the reference voltage makes it saturated (thus
reading out 0b1111111111), but I can imagine that any input voltage
above the chosen reference voltage might be damaging, because VCC is no
longer the reference.

> > I know the input range is specified between 0 and VCC but the sheet
> > also says that you only get valid results if the voltage is in
> > range of the reference voltage.
> Your post was based on your conclusions of what OCY said, not on the
datasheet or what you now say you knew.

That is correct, it was based on what I could think of being damaging to
the ADC, again by taking a reference lower than VCC and applying a
voltage between this reference and VCC.

> > I don't think it's a stupid question to ask what happens if the
> > input voltage for the ADC higher than the reference voltage (but
> > indeed lower than VCC), in terms of 'damaging' to the ADC.
> No it's not a supid question, but you didn't ask that, did you?

When I read back my question that actually is exactly what I'm asking, I
can't read it in any other way, quote: ...it is not damaging to the ADC
supplying a 3.6V source when using the internal 1.5V/2.5V reference?
(The original post referers to a 3.6V battery being used as VCC)

[...]
> So there you have it. It was all in the two most important documents
and you could have easily found it out by yourself, or
> at least post a proper question.
> All you had to do was just taken the time to write what you knew,
confirm what you were basing your assumptions on, and
> what your real question was based on that.
> So don't you feel unjustly treaten if I tell you to RTFM.

I could have if I started my own topic doing some proper research in the
first place. I was just wondered by the answer of OCY and I do not know
the datasheet nor the manual by heart, that's where my short remark came
from. I was not the topic starter, I might have helped him pointing in
the direction of taking more samples to get a better result when using
high value resistors and then OCY came with another important part: why
not use something that is already in the uC? I can't remember what my
assumptions were based on, but I can imagine 'thou should not apply a
higher voltage than Vref. A simple 'no that is not damaging as long as
the ADCs input voltage is lower than VCC' would have been ok. Short
question, short answer.

I don't know why you would react in such a way in the first place. There
are many questions coming by on the forum, some of them are really basic
and if the topic started would have taken a peek at the
examples/datasheet/manual provided with his microcontroller, he wouldn't
even have asked. On the other hand, if you don't already know, you might
not think of the solution being in a specific direction. The post of
'Pascal' about the Kyoto map is a good example of this I think.

But let's just end this here. The topic starter is satisfied, I now know
that it's not damaging to the ADC. Period.

Maybe we can start helping people (which I think many of the regular
posters like OCY, OneStone, Paul Curtis, Anders Lindgren, Dan
Bloomquist, Bart Oegema and many others do).

Thanks,
Hendrik

------------------------------------

______________________________
controlSUITE™ software. Comprehensive. Intuitive. Optimized.
Real-world software for real-time control. Details Here!

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Re: How to measuring the VCC by MSP430 - tintronic - Aug 25 12:37:35 2009

--- In m...@yahoogroups.com, Hendrik wrote:
>
> Aargh, why do we keep going on and on about all this. It was not my
> question/topic in the first place!
What does that have to do with anything?
A question was posted.
A reply said the answer could be found in the User's Guide.
You posted a follow-up question.
The answer was even more easy to find in any of the 2 most important documents as it was to find the answer to the first one.
I replied to you to RTFM.

> [OCY]
> > > > > > When Vcc is above 3.0V, ADC will be saturated. Thus I will
> > > > > > not be able to get the true voltage when it is above 3.0V,
> > > > > > but knowing that it is above 3.0V is good enough for me.
> > > > > old_cow_yellow: so you're saying that it is not damaging to the
> > > > > ADC supplying a 3.6V source when using the internal 1.5V/2.5V
> > > > > reference?
> > OCY didn't say that at all. Now I'm not even sure what you mean by
> "supplying 3.6V source". That post only shows that you
> > didn't even read OCY post twice. OCY presented you with VA11 = Vcc/2,
> which based on the other data he provided is 1.1 to
> > 1.8V.
>
> Perhaps the 'so you're saying' is not the right phrase here. He says
> that a voltage above the reference voltage makes it saturated (thus
> reading out 0b1111111111), but I can imagine that any input voltage
> above the chosen reference voltage might be damaging, because VCC is no
> longer the reference.
No, you're extrapolating outside what OCY wrote and you're asking about a specific case.
Your problem is the "I can imagine". You're making assumptions, and instead of searching if your assumption is right, you're asking the forum to do the searching for you.

> > > I know the input range is specified between 0 and VCC but the sheet
> > > also says that you only get valid results if the voltage is in
> > > range of the reference voltage.
> > Your post was based on your conclusions of what OCY said, not on the
> datasheet or what you now say you knew.
>
> That is correct, it was based on what I could think of being damaging to
> the ADC, again by taking a reference lower than VCC and applying a
> voltage between this reference and VCC.
Again, you think of something and don't bother checking it by yourself. You contradict yourself. You "know" the input range is between 0 and Vcc but you think a voltage between VR+ and Vcc might be damaging. So in fact you don't "know" the input range.

> > > I don't think it's a stupid question to ask what happens if the
> > > input voltage for the ADC higher than the reference voltage (but
> > > indeed lower than VCC), in terms of 'damaging' to the ADC.
> > No it's not a supid question, but you didn't ask that, did you?
>
> When I read back my question that actually is exactly what I'm asking, I
> can't read it in any other way, quote: ...it is not damaging to the ADC
> supplying a 3.6V source when using the internal 1.5V/2.5V reference?
> (The original post referers to a 3.6V battery being used as VCC)
I still don't know what you mean by supplying the ADC. Do you mean the ADCs AVcc power supply or an Ax voltage input? Neither makes sense since OCY wrote A11 Which is Vcc/2, so the only way for it to reach 3.6V was to power Vcc with 7.2V. Again, you're extrapolating and presenting a single case, when what you really want to know is what happens when VAx is outside VR- to VR+, or so it seamed on your next post.

> [...]
> > So there you have it. It was all in the two most important documents
> and you could have easily found it out by yourself, or
> > at least post a proper question.
> > All you had to do was just taken the time to write what you knew,
> confirm what you were basing your assumptions on, and
> > what your real question was based on that.
> > So don't you feel unjustly treaten if I tell you to RTFM.
>
> I could have if I started my own topic doing some proper research
> in the first place.
You didn't need a new topic, juts the PROPER RESEARCH. Don't you understand this is exactly whay I'm pointing to . You didn't do ANY RESEARCH. At least you admit you didn't do the proper research, so why are you still mad that I told you to RTFM?

>I was just wondered by the answer of OCY and I do not know
> the datasheet nor the manual by heart, that's where my short remark
> came from.
Neither do I, but if you can write in this forum then you can download the datasheets. Not the same as asking for directions in Kyoto, is it?

> I was not the topic starter, I might have helped him pointing in
> the direction of taking more samples to get a better result when using
> high value resistors and then OCY came with another important part: why
> not use something that is already in the uC? I can't remember what my
> assumptions were based on, but I can imagine 'thou should not apply a
> higher voltage than Vref.
So did you write that? No, you didn't, you just asked about a specific case, which apparently you would use to draw a general conclusion. And even if you had asked "Can I apply a voltage higher than Vref?", my answer would still have been RTFM. Only after that, if you are still unclear or don't understand something in the datasheet or user guide, ask about that. I even put myself in the case you had read the datasheet and hadn't understood it, I presented you a proper question and gave you the answer.

> A simple 'no that is not damaging as long as the ADCs input voltage
> is lower than VCC' would have been ok. Short question, short answer.
No it wouldn't be ok. It would not be beneficial to anyone. I'm surprised you would be ok if I had given you that answer. No explanation why it is not damaging or how I know it is not damaging? Inevitably, the next question anyone who still hasn't RTFM would ask is: "How do you know it is not damaging?"
By the way questions shouldn't be short, they should be as complete as possible without being superfluous.

> I don't know why you would react in such a way in the first place.
React in such a way? Somebody already pointed to reading the datasheet. You asked a follow-up question whose answer was also in the datasheet and even more easy to find, so I told you to RTFM. Since that you have been acting all offended.

> There are many questions coming by on the forum, some of them are
> really basic and if the topic started would have taken a peek at
> the examples/datasheet/manual provided with his microcontroller, he
> wouldn't even have asked.
And they should get a RTFM far more often than they do. But the first step is to point him to where the answer is so he can give it a try and find the answer by himself. That way in the future he will know where to look for and find the answer without needing to ask in a forum and wait for the answer. If he still hasn't found it, he can ask for more help. When the question is too basic, I prefer to give directions to where the answer was, but if the answer can't be easily found or understood, I take the time to explain. Other do this exact same thing as well.

> On the other hand, if you don't already know, you might
> not think of the solution being in a specific direction.
Exactly. That is why OneStone told him the answer was in the User's Guide.

> The post of
> 'Pascal' about the Kyoto map is a good example of this I think.
Not at all, but you can read the other answers to that post. This does reflect your way of thinking. You were just passing by this topic, a question popped in your mind, and you decided to throw it in, instead of doing the littlest bit of searching by yourself. It is easyier that way, and you don't have the time, so let someone else do the searching and give you the answer.
By the way, before going to the internet to ask somebody for directions in Santiago de Chile where I have lived for the past 2.5 years, I go to planos.cl, mapcity.cl and/or map.google.cl. If I want to use the public transport system, I go to transantiago.cl. Only then, if I still don't know my way, I ask somebody to help me.

> But let's just end this here. The topic starter is satisfied, I now know
> that it's not damaging to the ADC. Period.
That nice, and what started me writing this reply. "I'm right and I have the last word, so let's just end this here". Don't worry I won't be replying to this brach of this topic again.

> Maybe we can start helping people (which I think many of the regular
> posters like OCY, OneStone, Paul Curtis, Anders Lindgren, Dan
> Bloomquist, Bart Oegema and many others do).
How long have you being reading their replys? Did you read the replies to this topic? Both OCY and OneStone replied to you that your conclusion wasn't what OCY had said. But by all means, since you mention OneStone, let me quote the reply of OneStone to the same answer of OCY you posted your follow-up question to.

> > If I were you I would have made him go and read the manual to
> > find that out for himself, that way he might actually learn
> > something useful, but you are a much crueler man than I am. ;@}

And let me also quote OneStone's reply to my post to you:

> > Wow Michael, and I used to get hate mail because people thought I
> > was too cruel!!
> >
> > ;@}
> >
> > there's no such thing as too cruel, it's only varying degrees of
> > kindness.
> >
> > I'm no longer fat, merely anorexically challenged!!
> >
> > Cheers
> >
> > Al

You should take the time to read one of all those guides on how to ask questions in a forum the smart way. More than one has been posted here, the last one quite recently. I have read a few and each time a new one is posted, I read it from top to bottom. And what I find out each time is that I still too often post the answer to basic questions insted of telling people like yourself to RTFM. And I didn't just tell you to RTFM, I also told you how to arrive to the page where the answer is, which is far more helpful in the long run than just saying on which page.
If you are not willing to learn, what the hell are you doing here?

Sincerely,
Michael K.

------------------------------------

(You need to be a member of msp430 -- send a blank email to msp430-subscribe@yahoogroups.com )

Sign in

Search msp430

Subscribe to msp430

Ads

Discussion Groups

See Also

Discussion Groups | MSP430 | How to measuring the VCC by MSP430

How to measuring the VCC by MSP430 - =?GB2312?B?zuLU8bS+?= - Aug 23 8:31:15 2009

Re: How to measuring the VCC by MSP430 - Hendrik - Aug 23 10:10:49 2009

Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 10:50:13 2009

Re: How to measuring the VCC by MSP430 - Paul Curtis - Aug 23 10:57:08 2009

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 11:03:48 2009

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 11:08:22 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 13:51:55 2009

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 23 14:48:08 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 23 15:14:25 2009

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 23 16:00:12 2009

Re: Re: How to measuring the VCC by MSP430 - Paul Curtis - Aug 23 17:19:08 2009

Re: How to measuring the VCC by MSP430 - p_murayama - Aug 23 21:28:28 2009

Re: Re: How to measuring the VCC by MSP430 - =?GB2312?B?zuLU8bS+?= - Aug 23 21:54:40 2009

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 10:18:01 2009

Re: How to measuring the VCC by MSP430 - old_cow_yellow - Aug 24 10:44:51 2009

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 10:45:40 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 11:25:39 2009

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 24 12:00:34 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 12:19:34 2009

Re: Re: How to measuring the VCC by MSP430 - Augusto Einsfeldt - Aug 24 12:26:43 2009

Re: Re: How to measuring the VCC by MSP430 - Hugh Molesworth - Aug 24 12:58:10 2009

Re: Re: How to measuring the VCC by MSP430 - Bart Oegema - Aug 24 13:14:02 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 13:39:26 2009

Re: Re: How to measuring the VCC by MSP430 - Augusto Einsfeldt - Aug 24 14:08:39 2009

Re: How to measuring the VCC by MSP430 - tintronic - Aug 24 15:51:04 2009

Re: Re: How to measuring the VCC by MSP430 - OneStone - Aug 24 15:58:37 2009

Re: Re: How to measuring the VCC by MSP430 - Hendrik - Aug 25 4:10:45 2009

Re: How to measuring the VCC by MSP430 - tintronic - Aug 25 12:37:35 2009