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500ae5be17
This is useful in order to get visual indication that something did not succeed: # Give it 5 seconds to run echo 'sjjjjjA.' > /dev/led/error random_program echo '0' > /dev/led/error If random_program takes more than 5 seconds or if it hangs, the LED will be turned on.
166 lines
4.4 KiB
Groff
166 lines
4.4 KiB
Groff
.\" Copyright (c) 2003 Sergey A. Osokin <osa@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 3, 2003
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.Dt LED 4
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.Os
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.Sh NAME
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.Nm led
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.Nd API for manipulating LED's, lamps and other announciators.
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.Sh SYNOPSIS
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.In dev/led/led.h
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.Bd -literal
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typedef void led_t(void *priv, int onoff);
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.Ed
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.Ft dev_t
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.Fo led_create
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.Fa "led_t *func"
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.Fa "void *priv"
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.Fa "char const *name"
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.Fc
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.Ft void
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.Fo led_destroy
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.Fa "dev_t dev"
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.Fc
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.Sh DESCRIPTION
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The
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.Nm
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driver provides generic support for handling LEDs, lamps and other
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announciators.
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.Pp
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The hardware driver must supply a function to turn the announciator on and off
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and the device
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.Va name
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of the announciator relative "/dev/led/".
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The
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.Va priv
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argument is passed back to this on/off function and can be used however
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the hardware driver sees fit.
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.Pp
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The lamp can be controlled by opening and writing ascii strings to the
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"/dev/led/bla" device.
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.Pp
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In the following we will use this special notation to indicate the resulting
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output of the announciator:
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.Bl -tag -width Ds -offset indent -compact
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.It Ic *
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The announciator is on for 1/10th secound.
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.It Ic _
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The announciator is off for 1/10th secound.
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.El
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.Pp
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State can be set directly, and since the change happens immediately,
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it is possible to flash the announciator with very short periods and
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synchronize it with program events.
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It should be noted that there is a non-trivial overhead, so this may
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not be usable for benchmarking or measuring short intervals.
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.Bl -tag -width Ds -offset indent -compact
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.It Ic 0
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Turn the announciator off immediately.
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.It Ic 1
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Turn the announciator on immediately.
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.El
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.Pp
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Flashing can be set with a given period. The pattern continues endlessly.
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.Bl -tag -width Ds -offset indent -compact
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.It Ic f
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_*
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.It Ic f1
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_*
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.It Ic f2
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__**
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.It Ic f3
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___***
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.It Ic ...
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.It Ic f9
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_________*********
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.El
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.Pp
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Three high-level commands are available:
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.Bl -tag -width Ds -offset indent -compact
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.It Ic d%d
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numbers. Each digit is blinked out at 1/10th second, zero as
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ten pulses. Between digits a one second pause and after the last
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digit a two second pause after which the sequence is repeated.
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.It Ic s%s
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string.
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This gives full control over the announciator.
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Letters 'A' ... 'J' turns the announciator on for from 1/10th to one full
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second.
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Letters 'a' ... 'j' turns the announciator off for 1/10th
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to one full second.
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Unless terminated with a '.', the sequence is immediately repeated.
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.It Ic m%s
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morse.
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.Bl -tag -width Ds -offset indent -compact
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.It Ic '.'
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becomes _*
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.It Ic '-'
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becomes _***
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.It Ic ' '
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becomes __
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.It Ic '\en'
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becomes ____
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.El
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.Pp
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.El
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The sequence is repeated after a one second pause.
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.Sh EXAMPLES
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A 'd12' flashes the lamp
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.Bd -literal -offset indent
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*__________*_*______________________________
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.Ed
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.Pp
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A 'sAaAbBa' flashes
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.Bd -literal -offset indent
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_*_**__*
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.Ed
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.Pp
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/usr/games/morse -l "Soekris rocks" > /dev/led/error
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.Sh FILES
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.Bl -tag -width /dev/led/*
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.It Pa /dev/led/*
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.El
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.Sh SEE ALSO
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.Xr morse 6
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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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.Fx 5.2 .
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.Sh AUTHORS
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.An -nosplit
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This software was written by
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.An Poul-Henning Kamp
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.Aq phk@FreeBSD.org .
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.Pp
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This manual page was written by
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.An Sergey A. Osokin
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.Aq osa@FreeBSD.org
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and
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.An Poul-Henning Kamp
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.Aq phk@FreeBSD.org .
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