Hi Everybody,

After investigating the problems with some CompactFlash cards we have 
found out:

There are a number of CF cards that don't follow the ATA specs regarding 
to RESET line behavior, more specific, they totally ignore the RESET 
line....

There are two issues with that when using those CF cards in a net5501:

1) The "set flash=primary|secondary" setting is done by setting the CSEL 
(cable select) line to master or slave and then issue a reset. The CF 
card are then supposed to reset and recognize the new CSEL setting.

CF cards that don't do that will just use the hardware default. In early 
net5501 that was slave, we changed that to master so at least non 
standard CF cards could be used in the most common way.

2) Some boards have a problem with a short glitch on the DASP line. That 
shouldn't normally matter as we do a RESET afterwards, but again some CF 
cards ignore the RESET line.... If the CF card is master it will then 
wait 32 seconds for the slave response and if that is not present then 
the BIOS will time out and not recognize the CF card.

We will implement a hardware workaround for the glitch in future 
production series but the non standard CF cards will of course still 
only be master.

If a CF card cannot be set to slave then it do not follow the ATA 
standard and are not recommended to be used in Soekris boards.

We recommend to use Sandisk CF cards as they seems to always follow the 
specs and therefore work as expected.


Best Regards,


Soren Kristensen

CEO & Chief Engineer
Soekris Engineering, Inc.

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