Dear Group,
I'm writing a C program on my Debian system to read from an interface
board through the parallel port. I need to wait at least 300 microseconds
before reading from the next channel, to give the A/D converter on the
board time to stabilize, but I don't want to wait much longer (e.g., 10
milliseconds) because it will make the program too slow. The delay
functions (usleep, nanosleep...) only provide delays down to 10-30
milliseconds, despite their name, because they apparently yield the CPU to
other tasks with every call. The best solution I've found it to read (or
write) to a port (e.g., 0x80), which takes one microsecond. By doing this
300 times, I get something close to the wanted delay, plus a little
because of time sharing, but it is good enough. The only thing I don't
like is that my process takes about 97% of the CPU, even though it spends
almost all its time waiting. The CPU is a fanless 386, and it runs pretty
hot at 97% usage. Is there an elegant solution to this, or should I look
for a CPU fan? I would like to leave this a time-sharing system.
Thanks,
Chris
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