Specifications

Comedi
96 / 148
9 0 7 data 7
10 1 3 acknowledge
11 1 4 busy
12 1 2 output
13 1 1 printer selected
14 2 1 auto LF
15 1 0 error
16 2 2 init
17 2 3 select printer
18-25 ground
Subdevices 0 is digital I/O, subdevice 1 is digital input, and
subdevice 2 is digital output. Unlike other Comedi devices,
subdevice 0 defaults to output.
Pins 13 and 14 are inverted once by Comedi and once by the
hardware, thus cancelling the effect.
Pin 1 is a strobe, thus acts like one. There’s no way in software
to change this, at least on a standard parallel port.
Subdevice 3 pretends to be a digital input subdevice, but it always
returns 0 when read. However, if you run a command with
scan_begin_src=TRIG_EXT, it uses pin 10 as a external triggering
pin, which can be used to wake up tasks.
5.5.31 comedi_rt_timer -- Command emulator using real-time tasks
Author: ds, fmhess
Status: works
This driver requires RTAI or RTLinux to work correctly. It doesn’t
actually drive hardware directly, but calls other drivers and uses
a real-time task to emulate commands for drivers and devices that
are incapable of native commands. Thus, you can get accurately
timed I/O on any device.
Since the timing is all done in software, sampling jitter is much
higher than with a device that has an on-board timer, and maximum
sample rate is much lower.
Configuration options:
[0] - minor number of device you wish to emulate commands for
[1] - subdevice number you wish to emulate commands for
5.5.32 comedi_test -- generates fake waveforms
Author: Joachim Wuttke <[e-mail]>, Frank Mori Hess <[e-mail]>, ds