GPIOPWM(4) FreeBSD Kernel Interfaces Manual GPIOPWM(4)
NAME
gpiopwm - support for pulsing GPIO pins in software
SYNOPSIS
gpiopwm* at gpio? offset ? mask 1
gpiopwm* at gpio?
DESCRIPTION
The gpiopwm driver allows for pulsing GPIO pins in software using the
callout(9) facility. The pulse frequency and duty cycle are specified
indirectly by setting an "on" and "off" period, in ticks. Both values
are accessible as sysctl(3) variables.
SYSCTL VARIABLES
The following sysctl(3) variables are used to define the pulsing:
hw.gpiopwmN.off Define the "off" period in ticks.
hw.gpiopwmN.on Define the "on" period in ticks.
Only when both the "on" and the "off" period are set to values higher
than zero pulsing will start. To stop the pulsing, set either value to
zero.
EXAMPLES
To pulse a pin on a machine with 100 ticks/second with a frequency of 1Hz
and a duty cycle of 20%, the "on" period must be set to 20 and the "off"
period must be set to 80. The following example will pulse the error LED
of a Soekris net4801 with a frequency of 1 Hz and a duty cycle of 20%:
# gpioctl gpio0 20 set pp
# gpioctl gpio0 attach gpiopwm 20 1
# sysctl -w hw.gpiopwm0.off=80
# sysctl -w hw.gpiopwm0.on=20
SEE ALSO
gpio(4), intro(4), gpioctl(8), sysctl(8)
HISTORY
The gpiopwm driver first appeared in NetBSD 6.0.
AUTHORS
The gpiopwm driver was written by Marc Balmer <
[email protected]>.
FreeBSD 14.1-RELEASE-p8 November 13, 2011 FreeBSD 14.1-RELEASE-p8