1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3.\" 4.\" Copyright (c) 2017 Poul-Henning Kamp <phk@FreeBSD.org> 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd September 10, 2018 30.Dt BCM283X_PWM 4 31.Os 32.Sh NAME 33.Nm bcm283x_pwm 34.Nd bcm283x_pwm - driver for Raspberry Pi 2/3 PWM 35.Sh SYNOPSIS 36.Cd "kldload bcm283x_clkman" 37.Cd "kldload bcm283x_pwm" 38.Sh DESCRIPTION 39The 40.Nm 41driver provides access to the PWM engine on GPIO12 of Raspberry Pi 2 and 3 hardware. 42.Pp 43The PWM hardware is controlled via the 44.Xr sysctl 8 45interface: 46.Bd -literal 47dev.pwm.0.mode: 1 48dev.pwm.0.mode2: 1 49dev.pwm.0.freq: 125000000 50dev.pwm.0.ratio: 2500 51dev.pwm.0.ratio2: 2500 52dev.pwm.0.period: 10000 53dev.pwm.0.period2: 10000 54dev.pwm.0.pwm_freq: 12500 55dev.pwm.0.pwm_freq2: 12500 56.Ed 57.Bl -tag -width ".Va dev.pwm" 58.It Va dev.pwm.0.mode , dev.pwm.0.mode2 59PWM Mode for channels 1 and 2. 60Three modes exist, 0=off, 1=PWM, 2=N/M. 61The N/M mode is a first order delta-sigma mode, which makes a quite 62handy DAC output with a trivial RC lowpass filter. 63.Pp 64.It Va dev.pwm.0.freq 65The input frequency to the PWM hardware in Hz. 66Applies to both channels 1 and 2. 67Minimum frequency is 123 kHz, maximum frequency is 125 MHz. 68.It Va dev.pwm.0.period , dev.pwm.0.period2 69The period length in cycles. 70In PWM mode, the output frequencies will be 71( 72.Va dev.pwm.0.freq 73/ 74.Va dev.pwm.period 75) and ( 76.Va dev.pwm.0.freq2 77/ 78.Va dev.pwm.0.period2 79). 80In N/M mode this is the 'M'. 81.It Va dev.pwm.0.ratio , dev.pwm.0.ratio2 82The "on" period in cycles for PWM channels 1 and 2. 83In PWM mode, to get a 25% dutycycle, set this to 25% of 84.Va dev.pwm.0.period 85or 86.Va dev.pwm.0.period2 , 87as appropriate. 88In N/M mode this is the 'N'. 89.It Va dev.pwm.0.pwm_freq , dev.pwm.0.pwm_freq2 90The calculated PWM output frequencies in PWM mode, for channels 1 and 2. 91.El 92.Pp 93.Sh NOTES 94Currently the 95.Nm 96driver ignores the 'status="disabled"' flag in the DTB, assuming that 97if you load the driver, you want it to work. 98.Sh SEE ALSO 99.Xr sysctl 8 100.Sh HISTORY 101The 102.Nm 103driver first appeared in 104.Fx 12.0 . 105.Sh AUTHORS 106.An -nosplit 107The 108.Nm 109driver and this manual page were written by 110.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org . 111