comedi_set_clock_source — set master clock for a subdevice
|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
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
will be ignored.
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
This function is only useable
on subdevices that provide support for the
INSN_CONFIG_SET_CLOCK_SRC configuration instruction.