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I'm using an MC9S12A256. We recently installed them on our new boards
for our new product and I'm having an intermittent problem with my FW
downloads. It appears that in some cases the flash is not getting
erased (MASS ERASE command). I have measured my supply voltage at 4.7
V for Vdd and for the other 5V inputs on the chip.

What is the min Vdd required for flash erase and programming? Could
4.7 V be close to the border of this range?

Thanks,
Eric

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



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Hello Eric,

Power supply would be 5V -/+10%.
Therefore between 4.5V and 5.5V, so you are in the window.
However, you are not supposed to have I/O above Vdd. This is forcing
current into the MCU.
May be you should check the procedure for the erasure of the MCU and,
if power supplies seems to be a problem, confirm that you have proper
decoupling CLOSE TO the MCU as well: 100nF (and you can add an
electrochimic 1=B5F if you you really see current appeals but usually
not needed).

Cheers,
Alban.
http://claimid.com/AlbanRampon

--- In 6...@yahoogroups.com, "eric_cina" wrote:
>
> I'm using an MC9S12A256. We recently installed them on our new boards=20
> for our new product and I'm having an intermittent problem with my FW=20
> downloads. It appears that in some cases the flash is not getting=20
> erased (MASS ERASE command). I have measured my supply voltage at 4.7=20
> V for Vdd and for the other 5V inputs on the chip.=20
>=20
> What is the min Vdd required for flash erase and programming? Could=20
> 4.7 V be close to the border of this range?
>=20
> Thanks,
> Eric
>

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



(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )

I increased the 5 V supply voltage to 5 V from 4.7 V but it did not=20
seem to fix the problem with the flash erasing.

We basically used the same circuit we use for the A128, which has=20
worked for several years now, and just popped in the A256. Are there=20
any changes we should have made?

Thanks.

--- In 6...@yahoogroups.com, "Alban Rampon" wrote:
>
> Hello Eric,
>=20
> Power supply would be 5V -/+10%.
> Therefore between 4.5V and 5.5V, so you are in the window.
> However, you are not supposed to have I/O above Vdd. This is=20
forcing
> current into the MCU.
> May be you should check the procedure for the erasure of the MCU=20
and,
> if power supplies seems to be a problem, confirm that you have=20
proper
> decoupling CLOSE TO the MCU as well: 100nF (and you can add an
> electrochimic 1=B5F if you you really see current appeals but usually
> not needed).
>=20
> Cheers,
> Alban.
> http://claimid.com/AlbanRampon
>=20
> --- In 6...@yahoogroups.com, "eric_cina" wrote:
> >
> > I'm using an MC9S12A256. We recently installed them on our new=20
boards=20
> > for our new product and I'm having an intermittent problem with=20
my FW=20
> > downloads. It appears that in some cases the flash is not=20
getting=20
> > erased (MASS ERASE command). I have measured my supply voltage=20
at 4.7=20
> > V for Vdd and for the other 5V inputs on the chip.=20
> >=20
> > What is the min Vdd required for flash erase and programming?=20
Could=20
> > 4.7 V be close to the border of this range?
> >=20
> > Thanks,
> > Eric
>
------------------------------------



(You need to be a member of 68hc12 -- send a blank email to 68hc12-subscribe@yahoogroups.com )

How are you programming flash?
Did you rebuild the code?
Does the tool you use to program flash "know" about the new chip type?
------------------------------------



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