How do the COMEDI drivers control the timing under real time Linux? from $B>>:d(B $B5A:H(B on 2006-04-20 (gmane.linux.comedi)

From: $B>>:d(B $B5A:H(B <ymatsuzaka_at_hotmail.com>
Date: Thu, 20 Apr 2006 11:22:36 +0000

Dear COMEDI users,

 I have recently come across the COMEDI project and trying to comprehend 
how it works. My questions are as follows
1. How do the COMEDI drivers control the timing of sampling under real time 
Linux?
  As far as I checked the source code, the only place where real time timer 
is invoked is in comedi_rt_timer.o. However, COMEDI modules for data 
acquisition boards (e.g. ni_pcimio.o) do not seem to be dependent on this 
module. Modprobing DAQ modules does not load comedi_rt_timer.o, even under 
real timer kernel (I am using RTAI 3.1). Is it that most of the DAQ modules 
use the on-board timer to pace the sampling?
2. If the COMEDI drivers are designed to use the real time API provided by 
real time Linux, how do they switch to hard real time? By specifying 
TRIG_RT when calling comedi_command?

 Thanks in advance,

Yoshiya Matsuzaka

Received on 2006-04-20Z10:22:36