[En-Nut-Discussion] Bus timing on board with Ethernut1.3F compatible

[Ing. Jan Benda]

Hello,
I have a project based on Ethernut project 1.3F. I have many PCBs, some 
are functional, but few boards doesn't work. We are using our 
application for Ethernut, and basemon, testrtl for board testing.
Initial tests performed by Basemon firmware are succesful. Testrtl does 
not reports any harware problem.

But when I press X in Basemon (webserver should be started), nothing 
will be done. Acording to the logic analyzer seems that bus activity is 
stopped after some memory accesses. So I tested separately hardware 
controlled access to RAM, but no problem. I tried fast 16MHz crystal as 
well as 1 MHz internal oscillator.

There is written in Atmega128 datasheet that is recommended to use 
74AHC573 instead of 74HC573 for oscilator > 8MHz. Now I am using HC 
technology and waiting for AHC chips from supplier. I am not sure if 
problem with some system freezing is related with incorrect latch 
timing, because at lower oscillator frequencies (1MHz) 74HC573 should work.


My question please:

Do you have some skill with bus timing related to chips technology?

Thank you for answer.

With best regards

-- 
Ing. Jan Benda
COMAC spol. s r. o.
Spojovaci 362
Porici nad Sazavou, 257 21
Czech republic

tel.: +420 317 778 022
fax.: +420 317 778 024