Re: [OT] parallel port for IO?

2001-04-19 Thread Warner Losh
In message [EMAIL PROTECTED] David Miller writes: : Anyone know of a way to get a low cost port of some kind to to simple : state change detection? The specific purpose is to time external events : which are triggered by breaking an LED light beam. Millisecond resolution : would be fine. : :

Re: [OT] parallel port for IO?

2001-04-19 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Warner Losh writes: If you have only 1 source, then you can use the ack line of the parallel port and the ppi driver to get timestamped events. If you have more than one, then you might be able to wire a simple latch to the ACK line and sample of to 8 sources.

Re: [OT] parallel port for IO?

2001-04-19 Thread Warner Losh
In message 60546.987709317@critter Poul-Henning Kamp writes: : Use the pps driver and you get microsecond jitter with nanosecond : resolution. While I usually see microsecond jitter, I have seen it as high as a few milliseconds when the interrupt load on the machine was high and the cpu was

Re: [OT] parallel port for IO?

2001-04-19 Thread Poul-Henning Kamp
In message [EMAIL PROTECTED], Warner Losh writes: In message 60546.987709317@critter Poul-Henning Kamp writes: : Use the pps driver and you get microsecond jitter with nanosecond : resolution. While I usually see microsecond jitter, I have seen it as high as a few milliseconds when the interrupt

Re: [OT] parallel port for IO?

2001-04-19 Thread Warner Losh
In message 60866.987710568@critter Poul-Henning Kamp writes: : The BIOS misuse of SMM mode can give you jitter in the 1msec range : and there is not much you can do about it. I found out when I : clocked a motherboard with a 14.318 derived from a Rb, and timed : 1Hz pulses derived from a Cs.

Re: [OT] parallel port for IO?

2001-04-19 Thread Warner Losh
In message 66167.987742147@critter Poul-Henning Kamp writes: : Then the disk is probably running in PIO mode which thrashes your : interrrupts. That's likely right. This was a real low end machine, designed to be smalffl and cheap. : The pentium systems were much better about this. : :

[OT] parallel port for IO?

2001-04-13 Thread David Miller
Hi all;) Anyone know of a way to get a low cost port of some kind to to simple state change detection? The specific purpose is to time external events which are triggered by breaking an LED light beam. Millisecond resolution would be fine. I was thinking of sampling the parallel port