Steve Stallings wrote: > Peter, > > Good point about interrupt jitter mattering less if > the actual sample time does not jitter. Unfortunately > the current RTAI setup requires that the interrupt > comes from the host interrupt timers. If we could > get to a system model where the hardware could > sample the data at the same time that it also > requests an interrupt, then the actual interrupt > latency would be much less critical. All models of my hardware (PPMC, Univ. Stepper and Univ. PWM) have this feature. They can sample the encoder position at 1, 2.5, 5 or 10 KHz and send an interrupt request to the parallel port. > The PC system > design does not bring out the interrupt request > anywhere, so syncing with it in hardware is not > possible, nor can RTAI (as best I know) accept an > interrupt from external hardware as the system timer. > Yes, I believe RTAI has an option to trigger a thread from any interrupt. It might require a slight extension of rtapi to pass such a request through to RTAI.
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