VanLUG Email Archive
Dave Martindale (davem@zeppo.cs.ubc.ca)
Sun, 17 Jan 1999 01:40:06 -0800
There's always the route of taking a 10 MHz oscillator (you said 100
ns precision) and feeding it to a bunch of TTL decimal or binary counter
stages. 5 stages of decimal counting or 17 bits of binary counter give
you a period longer than 10 ms. Then put the whole thing onto an ISA
card so the contents of the register can be read back, and you've got
a timer with the performance you wanted that can be used by a program
busy-looping watching the register.
You can also add logic to clear the counter at a particular instant in
time, or load a specific value into it. Interrupt on overflow is another
option if you want an interrupt at the end of the period instead of
waiting in a loop reading the counter.
I've never built an ISA card, but something this simple-minded can't
be that hard.
Dave
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