Hello, Nayanip,

Thanks for the response. I have already managed the problem. The behaviour
was really tricky, so I thought it was some twisted logical error. Now I'm
pretty sure it was faulty power supply, but will not elaborate on that,
because it's not yet well examined (I had to move on with the software). I
have just used another board (same design) and it worked. Answering your
questions: I don't use external memory interface, just driving i/o ports. I
have AEN pulled down to the ground permanently (initially I thought it was
the problem - the lack of edges on AEN - but it wasn't).

I must say Davicom  support was very helpful (and very quick to help).

Thanks again for your response

Peter


Uzytkownik "Nayanip" <nps@spectrasmart-dot-com.no-spam.invalid> napisal w
wiadomosci news:UqKdnVcfW5SN3oXfRVn_vQ@giganews.com...
> Hello Piotr Golabek,
>
> How did yo connect DM9000 to Mega128?  mapped into the processor's
> external address or software simulation of i/o ports? What is the
> status of AEN pin when you are writing (reading) dm9000?
>
> Regards
>

Hello Piotr Golabek,

How did yo connect DM9000 to Mega128?  mapped into the processor's
external address or software simulation of i/o ports? What is the
status of AEN pin when you are writing (reading) dm9000? 

Regards

Hi,
 
I'm prototyping ATMEGA128 + DM9000 hardware. I have run into strange
problem, creating the driver for DM9000. I can read the registers, but
cannot write them.
More specifically: I cannot write the DATA (CMD pin = 1) location,
although there is no problem with writing the INDEX (CMD pin = 0)
location - I can read the default values of the registers and this
requires succesful write operation to INDEX. Of course, I have checked
with the oscilloscope all the signals, levels and timings of the DATA
write cycle and they look OK. Of course the CMD pin is given high
level, there is nIOW pulse, etc.

The code is based on the linux driver from the Davicom's site, and
cross-verified by reading the app. note. Essentialy, I only add the
implementation of the "atom" in, out operations. I have made the
general I/O interface to the DM9000 bus, that means, the code controls
every line of the bus separately - I don't use memory read/write
instructions.

There is one hardware change with respect to the reference design. I
have made a fixed connection of the nAEN pin to the ground (just
saving one ATMEGA pin...), meaning, the DM9000 is chip-selected all
the time. Maybe that's the problem? Maybe DM9000 possibly needs the
falling edge on the nAEN pin to write the INDEX location?
Any suggestions? Any kind of hint from you has a potential to cut down
my suffering :)