d7eb38c008
Many thanks to ian who gently provided me the DS1307 breakout board. Tested on: Raspberry pi Differential Revision: https://reviews.freebsd.org/D2022 Reviewed by: rpaulo
132 lines
3.5 KiB
Groff
132 lines
3.5 KiB
Groff
.\"
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.\" Copyright (c) 2015 Luiz Otavio O Souza <loos@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 ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 7, 2015
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.Dt DS1307 4
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.Os
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.Sh NAME
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.Nm ds1307
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.Nd 64 x 8, serial, i2c real-time clock
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.Sh SYNOPSIS
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.Cd "device iic"
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.Cd "device iicbus"
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.Cd "device ds1307"
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.Sh DESCRIPTION
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The
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.Nm
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serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD)
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clock/calendar plus 56 bytes of NV SRAM.
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.Pp
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The
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.Nm
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has a built-in power-sense circuit that detects power failures and
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automatically switches to the backup supply.
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Timekeeping operation continues while the part operates from the backup supply.
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.Pp
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Access to
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.Nm
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settings is made with the
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.Xr sysctl 8
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interface:
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.Bd -literal
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dev.ds1307.0.%desc: Maxim DS1307 RTC
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dev.ds1307.0.%driver: ds1307
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dev.ds1307.0.%location: addr=0xd0
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dev.ds1307.0.%pnpinfo: name=rtc compat=maxim,ds1307
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dev.ds1307.0.%parent: iicbus1
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dev.ds1307.0.sqwe: 1
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dev.ds1307.0.sqw_freq: 32768
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dev.ds1307.0.sqw_out: 0
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.Ed
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.Bl -tag -width ".Va dev.ds1307.%d.sqw_freq"
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.It Va dev.ds1307.%d.sqwe
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If set to 1, the SQW pin drives a square-wave of
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.Va dev.ds1307.%d.sqw_freq
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frequency.
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If set to 0, the output level of SQW pin is controlled by
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.Va dev.ds1307.%d.sqw_out .
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.It Va dev.ds1307.%d.sqw_freq
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Select the frequency of the SQW pin when the square-wave output is enabled on
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.Va dev.ds1307.%d.sqwe .
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It can be set to 1, 4096, 8192 and 32768.
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.It Va dev.ds1307.%d.sqw_out
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Set the output level of the SQW pin when
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.Va dev.ds1307.%d.sqwe
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is set to 0.
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.El
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.Pp
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Please check the
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.Nm
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datasheet for more details.
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.Pp
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On a
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.Xr device.hints 5
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based system, such as
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.Li MIPS ,
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these values are configurable for
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.Nm :
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.Bl -tag -width ".Va hint.ds1307.%d.addr"
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.It Va hint.ds1307.%d.at
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The
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.Xr iicbus 4
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that the
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.Nm
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is connected to.
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.It Va hint.ds1307.%d.addr
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The i2c address of
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.Nm .
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.El
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.Pp
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On a
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.Xr FDT 4
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based system the following properties must be set:
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.Bl -tag -width ".Va compatible"
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.It Va compatible
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Must always be set to "dallas,ds1307" or "maxim,ds1307".
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.It Va reg
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The i2c address of
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.Nm .
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The default address for
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.Nm
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is 0xd0.
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.El
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.Sh SEE ALSO
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.Xr fdt 4 ,
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.Xr iic 4 ,
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.Xr iicbus 4 ,
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.Xr sysctl 8
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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 11.0 .
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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 and this manual page were written by
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.An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org .
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