> 
> I overlooked delay() units.  Well, have tried with smaller delay values but
> it keeps failing.

In that case the delay is needed for something else!

> Here are all reset related timings present in the datasheet,
> in case I got them wrong:
> 
> RESET Active Low Pulsewidth - Max empty
> RESER Inactive to BIT_CLK Startup Delay - Max 400,000 ns
> Setup to RESET Inactive (SYNC, SDATA_OUT) - Min 15 ns, Max empty
> Rising Edge of RESET to Hi-Z Delay - 25 ns
> RESET Rise Time - 50 ns

My guess is that the device ID (and other config) is being read in from
a serial EPROM.  So that after a hard reset you have to wait long enough
for that to have been read.

Might be worth looking what the BIT_CLK is used for - if you need it to
be running the delay is quite long (also check it applies to software
resets though).

> 
> auvia has a TIMEOUT=50 constant that specifies how many loop iterations
> should be done waiting for a read.  I guess this computer is so fast
> (XP2600+) that the 50 value is not enough (it's not a delay()).

That is just plain borked - the compiler could even optimse the loop away!


	David

-- 
David Laight: david@l8s.co.uk