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Discussion Groups | Rabbit-Semi | Rabbit serial Volt levels
This is a group for folks designing and programming embedded systems using the Rabbit Semiconductor C-programmable microcontroller. Rabbit Semi is a spin-off from Z-World who makes a variety of embedded modules and tools. This group is not affiliated with either Rabbit or Z-World, but is a user forum for sharing ideas, asking questions, flaunting knowledge, and other typical user group stuff. The Rabbit is a powerful uC, supported by a full-featured C-compiler.
Rabbit serial Volt levels - Adnan Mohammad-Ali - May 27 9:43:53 2008
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a
bit of a problem. We are trying to communicate to a device that is able
to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is
also powered by the Tx line from the RS-232. The minimum requirements
for this device are that the Tx line requires to be at least 7V when
transmitting. When I referred to the data sheet of the OP7200 it states
the voltage level is "approximately +-10V". unfortunately when I measure
the Tx line when the device not transmitting, I receive 6.97V steady
from an older OP7200 we had on a development board and 7V steady on a
brand new one. Because of this, it provides insufficient voltage to
operate this device. When the device starts to transmit, the voltage
levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
We are trying to use the serial port C on the OP7200, but we came to a
bit of a problem. We are trying to communicate to a device that is able
to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is
also powered by the Tx line from the RS-232. The minimum requirements
for this device are that the Tx line requires to be at least 7V when
transmitting. When I referred to the data sheet of the OP7200 it states
the voltage level is "approximately +-10V". unfortunately when I measure
the Tx line when the device not transmitting, I receive 6.97V steady
from an older OP7200 we had on a development board and 7V steady on a
brand new one. Because of this, it provides insufficient voltage to
operate this device. When the device starts to transmit, the voltage
levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
RE: Rabbit serial Volt levels - "Vinay Raiker (RBEI/EEG3)" - May 27 10:17:30 2008
Hello Adan,
I think by using level shifter circuit you can achive the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a bit of a problem. We are trying to communicate to a device that is able to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is also powered by the Tx line from the RS-232. The minimum requirements for this device are that the Tx line requires to be at least 7V when transmitting. When I referred to the data sheet of the OP7200 it states the voltage level is "approximately +-10V". unfortunately when I measure the Tx line when the device not transmitting, I receive 6.97V steady from an older OP7200 we had on a development board and 7V steady on a brand new one. Because of this, it provides insufficient voltage to operate this device. When the device starts to transmit, the voltage levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
I think by using level shifter circuit you can achive the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a bit of a problem. We are trying to communicate to a device that is able to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is also powered by the Tx line from the RS-232. The minimum requirements for this device are that the Tx line requires to be at least 7V when transmitting. When I referred to the data sheet of the OP7200 it states the voltage level is "approximately +-10V". unfortunately when I measure the Tx line when the device not transmitting, I receive 6.97V steady from an older OP7200 we had on a development board and 7V steady on a brand new one. Because of this, it provides insufficient voltage to operate this device. When the device starts to transmit, the voltage levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
RE: RE: Rabbit serial Volt levels - Adnan Mohammad-Ali - May 28 10:37:38 2008
Hello Vinay,
Do you mean have some sort of intermediate circuit (to
increase the voltage level 7 - 10V) between the Rabbit processor and the
rs-232 converter?
Do you know of any such component that is CE?
Thankyou kindly for your reply
Adnan Mohammad-Ali
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Vinay Raiker (RBEI/EEG3)
Sent: Wednesday, 28 May 2008 12:10 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Adan,
I think by using level shifter circuit you can achive
the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a
bit of a problem. We are trying to communicate to a device that is able
to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is
also powered by the Tx line from the RS-232. The minimum requirements
for this device are that the Tx line requires to be at least 7V when
transmitting. When I referred to the data sheet of the OP7200 it states
the voltage level is "approximately +-10V". unfortunately when I measure
the Tx line when the device not transmitting, I receive 6.97V steady
from an older OP7200 we had on a development board and 7V steady on a
brand new one. Because of this, it provides insufficient voltage to
operate this device. When the device starts to transmit, the voltage
levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Do you mean have some sort of intermediate circuit (to
increase the voltage level 7 - 10V) between the Rabbit processor and the
rs-232 converter?
Do you know of any such component that is CE?
Thankyou kindly for your reply
Adnan Mohammad-Ali
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Vinay Raiker (RBEI/EEG3)
Sent: Wednesday, 28 May 2008 12:10 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Adan,
I think by using level shifter circuit you can achive
the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a
bit of a problem. We are trying to communicate to a device that is able
to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is
also powered by the Tx line from the RS-232. The minimum requirements
for this device are that the Tx line requires to be at least 7V when
transmitting. When I referred to the data sheet of the OP7200 it states
the voltage level is "approximately +-10V". unfortunately when I measure
the Tx line when the device not transmitting, I receive 6.97V steady
from an older OP7200 we had on a development board and 7V steady on a
brand new one. Because of this, it provides insufficient voltage to
operate this device. When the device starts to transmit, the voltage
levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
Re: Rabbit serial Volt levels - mehiegl - May 28 12:53:45 2008
You are up against the limitations of the RS-232 driver circuit on the
OP7200. If you look at the specs for the SP232 chip, the output could
be as low as 5V with a 3K load resistance. If your device requires 10
mA at 7V, that's equivalent to 700 ohms.
The only way I see that you may be able to increase the output voltage
is to increase value of the capacitors on the board for the SP232
charge pump. You might want to try tacking larger values across the
existing parts to see if it helps. You should refer to the datasheet
for max values, but 1uF is typically OK and pay attention to polarity
if you use polarized caps.
I'm not sure of Rabbit's policy, but I am guessing doing this would
void the warranty.
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
OP7200. If you look at the specs for the SP232 chip, the output could
be as low as 5V with a 3K load resistance. If your device requires 10
mA at 7V, that's equivalent to 700 ohms.
The only way I see that you may be able to increase the output voltage
is to increase value of the capacitors on the board for the SP232
charge pump. You might want to try tacking larger values across the
existing parts to see if it helps. You should refer to the datasheet
for max values, but 1uF is typically OK and pay attention to polarity
if you use polarized caps.
I'm not sure of Rabbit's policy, but I am guessing doing this would
void the warranty.
------------------------------------
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
RE: Re: Rabbit serial Volt levels - Adnan Mohammad-Ali - May 28 21:27:19 2008
That sounds it could work, but it's not something that I could because I
require to keep the warranty and plus because I have a fair few OP7200
that have the same the same "limitation" and need to utilise the RS-232
port at 10V I don't have the resources to change all of them L L
Has anyone else had this same problem?
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of mehiegl
Sent: Thursday, 29 May 2008 2:54 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Re: Rabbit serial Volt levels
You are up against the limitations of the RS-232 driver circuit on the
OP7200. If you look at the specs for the SP232 chip, the output could
be as low as 5V with a 3K load resistance. If your device requires 10
mA at 7V, that's equivalent to 700 ohms.
The only way I see that you may be able to increase the output voltage
is to increase value of the capacitors on the board for the SP232
charge pump. You might want to try tacking larger values across the
existing parts to see if it helps. You should refer to the datasheet
for max values, but 1uF is typically OK and pay attention to polarity
if you use polarized caps.
I'm not sure of Rabbit's policy, but I am guessing doing this would
void the warranty.
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
require to keep the warranty and plus because I have a fair few OP7200
that have the same the same "limitation" and need to utilise the RS-232
port at 10V I don't have the resources to change all of them L L
Has anyone else had this same problem?
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com]
On Behalf Of mehiegl
Sent: Thursday, 29 May 2008 2:54 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Re: Rabbit serial Volt levels
You are up against the limitations of the RS-232 driver circuit on the
OP7200. If you look at the specs for the SP232 chip, the output could
be as low as 5V with a 3K load resistance. If your device requires 10
mA at 7V, that's equivalent to 700 ohms.
The only way I see that you may be able to increase the output voltage
is to increase value of the capacitors on the board for the SP232
charge pump. You might want to try tacking larger values across the
existing parts to see if it helps. You should refer to the datasheet
for max values, but 1uF is typically OK and pay attention to polarity
if you use polarized caps.
I'm not sure of Rabbit's policy, but I am guessing doing this would
void the warranty.
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
RE: RE: Rabbit serial Volt levels - "Vinay Raiker (RBEI/EEG3)" - May 29 11:49:49 2008
One such circuit is
A level shift circuit comprises an inverter connected to a first voltage supply source and supplied with an input pulse. A condenser and a directional switching element are connected in series between the output point of the inverter and one potential point of the first voltage supply source. The input of a first MOS-FET is connected to the output of the inverter while the input of a second MOS-FET is connected to a connection point between the condenser and the directional switching element. The source of the first MOS-FET is connected to a common terminal of first and second voltage supply sources while the source of the second MOS-FET is connected to the other terminal of the second voltage supply source. An output voltage is generated between a common connecting point of the drains of the first and second MOS-FETs and one potential point of the second voltage supply source.
You can search in internet for more circuits
And also you can try changing the resistors in RS232 Converter with potentiometer and fix up with right resister (might work)
Best Regards,
Vinay Raiker
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Wednesday, 28. May 2008 5:50 AM
To: r...@yahoogroups.com
Subject: RE: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Vinay,
Do you mean have some sort of intermediate circuit (to increase the voltage level 7 - 10V) between the Rabbit processor and the rs-232 converter?
Do you know of any such component that is CE?
Thankyou kindly for your reply
Adnan Mohammad-Ali
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Vinay Raiker (RBEI/EEG3)
Sent: Wednesday, 28 May 2008 12:10 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Adan,
I think by using level shifter circuit you can achive the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a bit of a problem. We are trying to communicate to a device that is able to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is also powered by the Tx line from the RS-232. The minimum requirements for this device are that the Tx line requires to be at least 7V when transmitting. When I referred to the data sheet of the OP7200 it states the voltage level is "approximately +-10V". unfortunately when I measure the Tx line when the device not transmitting, I receive 6.97V steady from an older OP7200 we had on a development board and 7V steady on a brand new one. Because of this, it provides insufficient voltage to operate this device. When the device starts to transmit, the voltage levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )
A level shift circuit comprises an inverter connected to a first voltage supply source and supplied with an input pulse. A condenser and a directional switching element are connected in series between the output point of the inverter and one potential point of the first voltage supply source. The input of a first MOS-FET is connected to the output of the inverter while the input of a second MOS-FET is connected to a connection point between the condenser and the directional switching element. The source of the first MOS-FET is connected to a common terminal of first and second voltage supply sources while the source of the second MOS-FET is connected to the other terminal of the second voltage supply source. An output voltage is generated between a common connecting point of the drains of the first and second MOS-FETs and one potential point of the second voltage supply source.
You can search in internet for more circuits
And also you can try changing the resistors in RS232 Converter with potentiometer and fix up with right resister (might work)
Best Regards,
Vinay Raiker
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Wednesday, 28. May 2008 5:50 AM
To: r...@yahoogroups.com
Subject: RE: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Vinay,
Do you mean have some sort of intermediate circuit (to increase the voltage level 7 - 10V) between the Rabbit processor and the rs-232 converter?
Do you know of any such component that is CE?
Thankyou kindly for your reply
Adnan Mohammad-Ali
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Vinay Raiker (RBEI/EEG3)
Sent: Wednesday, 28 May 2008 12:10 AM
To: r...@yahoogroups.com
Subject: [rabbit-semi] RE: Rabbit serial Volt levels
Hello Adan,
I think by using level shifter circuit you can achive the required voltage on output lines.
Best Regards,
Vinay
________________________________
From: r...@yahoogroups.com [mailto:r...@yahoogroups.com] On Behalf Of Adnan Mohammad-Ali
Sent: Tuesday, 27. May 2008 2:34 PM
To: r...@yahoogroups.com
Subject: [rabbit-semi] Rabbit serial Volt levels
Hello Everyone
We are trying to use the serial port C on the OP7200, but we came to a bit of a problem. We are trying to communicate to a device that is able to convert the RS-232 levels to CMOS/TTL levels of 3.3V; this device is also powered by the Tx line from the RS-232. The minimum requirements for this device are that the Tx line requires to be at least 7V when transmitting. When I referred to the data sheet of the OP7200 it states the voltage level is "approximately +-10V". unfortunately when I measure the Tx line when the device not transmitting, I receive 6.97V steady from an older OP7200 we had on a development board and 7V steady on a brand new one. Because of this, it provides insufficient voltage to operate this device. When the device starts to transmit, the voltage levels further decreases as expected.
My question: is there a way I am able to achieve +-10V?
The device I'm using consumes "under 10mA"
Kindest Regards
Rony
(You need to be a member of rabbit-semi -- send a blank email to rabbit-semi-subscribe@yahoogroups.com )