[olug] Parallel port interrupt

[Eric Penne]

Has anybody used interrupts on the parallel port for data logging in Linux?

The problem is simple.  We want to monitor the power used by our facility.
 We have a device that outputs a pulse at a time interval based on how
much power we are using.  For example 1 pulse per second for using 10kW
and 2 pulses per second for 20kW.  Therefore each pulse corresponds to
2.7kWh.

The pulse needs to be picked up by the computer and an interrupt routine
would get the time of day to the nearest millisecond (or second).  How
fast are the pulses going to be coming in versus how fast the computer
responds to the parallel interrupt?  We don't know that yet since the
device hasn't been installed.  This can be done using RTLinux but we would
like to see if it can be done using a regular kernel.

The functions in time.h can do milli/microsecond accuracy but the big
question is how fast can the kernel respond to the parallel port
interrupt?


Eric