[En-Nut-Discussion] Ethernut 1.3H External RAM problem

[Ayman Hendawy]

Hi,

Yes Oli, you are right, I destroyed my board with applying 12V instead of
5V on the VCC supply line, and I found that the Ethernet, Buffer, SRAM ICs,
all burned, I replaced them, the Ethernet and buffer is working I test
them, and according to the ATmega128, I has to put buffer of AHC family not
HC, and I already did it.

so now I have Ethernet & Buffer ICs working, but the SRAM chip not working.

do you think that the over voltage , may burn some lines between SRAM and
uC?, recently I noticed some strange behavior for the uC, e.g: I can't do
any while loop that include any kind of delay, I can't blink led with time
delay 1 sec, also it's supposed that most of applications that doesn't
have Ethernet code to work fine without external RAM, however I just can
run only Basemon application only, any other simple application  doesn't
work on my uC, what does't mean?

Thanks

On Mon, Dec 17, 2012 at 1:49 PM, Ole Reinhardt <ole.reinhardt at embedded-it.de
> wrote:

> Hi
>
> > I have post this problem before but I didn't fix it yet, here is the
> update,
> >
> > Recently I repalced the SRAM K6X0808C1D-BF55, with K6X0808C1D-BF70, but
> it
> > doesn't work, I don't know what I have to do to test it, what I have to
> > check, I tried the SRAM test of Basemon, it give me an error message"No
> RAM
> > at 0x8000", I read the MCUCR, & XMCRA registers, it was zero both of
> them,
> > what dose it mean?
>
> If I remember you said, that you destroyed your board by overvoltage and
> then replaced the chips, right?
>
> Have you ever thought about replacing the CPU as well? Perhaps some
> lines of the data / address bus are not working any more?
>
> Bye,
>
> Ole
>
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-- 
Best regards

Ayman Hendawy
Embedded system engineer

Cairo,Egypt

Phone: +20110406659