2014-03-18 22:20:35 +04:00
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.\" $NetBSD: gpiopwm.4,v 1.5 2014/03/18 18:20:39 riastradh Exp $
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2011-11-13 16:35:40 +04:00
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.\"
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.\" Copyright (c) 2011 Marc Balmer <marc@msys.ch>
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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.\" purpose with or without fee is hereby granted, provided that the above
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.\" copyright notice and this permission notice appear in all copies.
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.\"
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.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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2011-11-13 23:31:05 +04:00
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.Dd November 13, 2011
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2011-11-13 16:35:40 +04:00
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.Dt GPIOPWM 4
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.Os
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.Sh NAME
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.Nm gpiopwm
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.Nd support for pulsing GPIO pins in software
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.Sh SYNOPSIS
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.Cd "gpiopwm* at gpio? offset ? mask 1"
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.Cd "gpiopwm* at gpio?"
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.Sh DESCRIPTION
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The
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.Nm
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driver allows for pulsing GPIO pins in software using the
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.Xr callout 9
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facility.
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2011-11-13 23:31:05 +04:00
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The pulse frequency and duty cycle are specified indirectly by setting an
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.Dq on
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and
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.Dq off
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period, in ticks.
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2011-11-13 16:35:40 +04:00
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Both values are accessible as
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2011-11-13 23:31:05 +04:00
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.Xr sysctl 3
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2011-11-13 16:35:40 +04:00
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variables.
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.Sh SYSCTL VARIABLES
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The following
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2011-11-13 23:31:05 +04:00
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.Xr sysctl 3
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2011-11-13 16:35:40 +04:00
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variables are used to define the pulsing:
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2013-06-04 16:11:12 +04:00
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.Bl -tag -width hw.gpiopwmN.off
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2011-11-13 16:35:40 +04:00
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.It hw.gpiopwmN.off
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2011-11-13 23:31:05 +04:00
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Define the
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.Dq off
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period in ticks.
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2011-11-13 16:35:40 +04:00
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.It hw.gpiopwmN.on
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2011-11-13 23:31:05 +04:00
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Define the
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.Dq on
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period in ticks.
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2011-11-13 16:35:40 +04:00
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.El
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.Pp
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2011-11-13 23:31:05 +04:00
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Only when both the
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.Dq on
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and the
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.Dq off
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period are set to values higher than zero pulsing will start.
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2011-11-13 16:35:40 +04:00
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To stop the pulsing, set either value to zero.
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.Sh EXAMPLES
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To pulse a pin on a machine with 100 ticks/second with a frequency of 1Hz and a
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2011-11-13 23:31:05 +04:00
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duty cycle of 20%, the
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.Dq on
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period must be set to 20 and the
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.Dq off
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period must be set to 80.
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2011-11-13 16:35:40 +04:00
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The following example will pulse the error LED of a Soekris net4801
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with a frequency of 1 Hz and a duty cycle of 20%:
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.Bd -literal
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# gpioctl gpio0 20 set pp
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# gpioctl gpio0 attach gpiopwm 20 1
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# sysctl -w hw.gpiopwm0.off=80
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# sysctl -w hw.gpiopwm0.on=20
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.Ed
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.Sh SEE ALSO
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.Xr gpio 4 ,
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2011-11-13 23:31:05 +04:00
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.\" .Xr gpioattach 4 ,
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.Xr intro 4 ,
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2011-11-13 16:35:40 +04:00
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.Xr gpioctl 8 ,
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2011-11-13 23:31:05 +04:00
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.Xr sysctl 8
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2011-11-13 16:35:40 +04:00
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Nx 6.0 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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driver was written by
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2013-07-21 01:39:55 +04:00
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.An Marc Balmer Aq Mt marc@msys.ch .
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