On 2012-01-21, Hal Murray <[email protected]> wrote: > In article <[email protected]>, > unruh <[email protected]> writes: >>Further to my kernel pps problems. I have now managed to get pps-ldisc >>which is supposed to timestamp the serial port DCD transition interrupt, >>and the pps_parport. In the case of the latter I was wondering if anyone >>has any idea of how it works. The on board parallel port interface on >>old motherboards used the edge transition to signal the interrupt. This >>would mean that once the routine had serviced the interrupt, no other >>one would occur until that next edge. However, for the add in parallal >>cards, they use shareable, level triggered interrupts. Since the input pulse >>is >>many ms long, this means that the interrupt keeps triggering about once >>every usec as long as the ack line is up. >>Does anyone know if the pps_parport module treats such shareable >>interrupts correctly? > > Usually, that sort of hardware has a way to turn off the interrupt. > It's something like you write a bit in a register to "ACK" that > interrupt. When the external signal turns off, it clears that bit. > > The info should be in the fine print if you can get a good data sheet.
I have looked carefully, and can onlyfind a bit for turning off interrupts (which of course does not turn on again). That would be fine if it were edge triggered, but not for level triggered. > _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
