comedi_set_clock_source — set master clock for a subdevice
#include <comedilib.h>
int comedi_set_clock_source( | comedi_t * device, |
| unsigned int subdevice, | |
| unsigned int channel, | |
| unsigned int clock, | |
unsigned int period_ns); |
This function selects a master clock for a subdevice. The clock
parameter selects the master clock, and is driver-dependant.
If the subdevice does not support configuring its master clocks on a
per-channel basis, then the channel parameter
will be ignored.
The period_ns
parameter specifies the clock's period in nanoseconds. It may left unspecified by using
a value of zero. Drivers will ignore the clock period if they already
know what the clock period should be for the specified clock (e.g. for an
on-board 20MHz oscillator). Certain boards which use a phase-locked loop to
synchronize to external clock sources must be told the period of the external
clock. Specifying a clock period for an external clock may also allow
the driver to support TRIG_TIMER sources in commands while
using the external clock.
The clock may be queried with the
comedi_get_clock_source
function.
This function is only useable
on subdevices that provide support for the
INSN_CONFIG_SET_CLOCK_SRC configuration instruction.