Is it possible for you to borrow a logic analyzer? This is admittedly a
real long shot given their high cost, but I solved a lot of early
problems with parallel port transactions based on having that trace of
the genuine wire behavior.
I've analyzed the present negotiation logic with several parallel port
products and not found problems with it. It has revealed some problems
with devices and with other software. For example, I had a bug where I
caused a glitch on one line by failure to properly initialize a
variable, which led my code to toggle one of the control lines before
going into negotiation. The glitch was only 200ns but that was enough
to cause the subsequent negotiation to fail. The device was not in the
proper state for negotiation any more. (The problem was of course
intermittent based on whatever that uninitialized variable contained. A
good analyzer lets you program complex capture triggers to deal with
intermittent failures like that.)
R Horn
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This archive was generated by hypermail 2b29 : Thu Nov 16 2000 - 12:33:42 EST