1.\" 2.\" Copyright (c) 2015 Luiz Otavio O Souza <loos@freebsd.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd March 7, 2015 28.Dt DS1307 4 29.Os 30.Sh NAME 31.Nm ds1307 32.Nd 64 x 8, serial, i2c real-time clock 33.Sh SYNOPSIS 34.Cd "device iic" 35.Cd "device iicbus" 36.Cd "device ds1307" 37.Sh DESCRIPTION 38The 39.Nm 40serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) 41clock/calendar plus 56 bytes of NV SRAM. 42.Pp 43The 44.Nm 45has a built-in power-sense circuit that detects power failures and 46automatically switches to the backup supply. 47Timekeeping operation continues while the part operates from the backup supply. 48.Pp 49Access to 50.Nm 51settings is made with the 52.Xr sysctl 8 53interface: 54.Bd -literal 55dev.ds1307.0.%desc: Maxim DS1307 RTC 56dev.ds1307.0.%driver: ds1307 57dev.ds1307.0.%location: addr=0xd0 58dev.ds1307.0.%pnpinfo: name=rtc compat=maxim,ds1307 59dev.ds1307.0.%parent: iicbus1 60dev.ds1307.0.sqwe: 1 61dev.ds1307.0.sqw_freq: 32768 62dev.ds1307.0.sqw_out: 0 63.Ed 64.Bl -tag -width ".Va dev.ds1307.%d.sqw_freq" 65.It Va dev.ds1307.%d.sqwe 66If set to 1, the SQW pin drives a square-wave of 67.Va dev.ds1307.%d.sqw_freq 68frequency. 69If set to 0, the output level of SQW pin is controlled by 70.Va dev.ds1307.%d.sqw_out . 71.It Va dev.ds1307.%d.sqw_freq 72Select the frequency of the SQW pin when the square-wave output is enabled on 73.Va dev.ds1307.%d.sqwe . 74It can be set to 1, 4096, 8192 and 32768. 75.It Va dev.ds1307.%d.sqw_out 76Set the output level of the SQW pin when 77.Va dev.ds1307.%d.sqwe 78is set to 0. 79.El 80.Pp 81Please check the 82.Nm 83datasheet for more details. 84.Pp 85On a 86.Xr device.hints 5 87based system, such as 88.Li MIPS , 89these values are configurable for 90.Nm : 91.Bl -tag -width ".Va hint.ds1307.%d.addr" 92.It Va hint.ds1307.%d.at 93The 94.Xr iicbus 4 95that the 96.Nm 97is connected to. 98.It Va hint.ds1307.%d.addr 99The i2c address of 100.Nm . 101.El 102.Pp 103On a 104.Xr FDT 4 105based system the following properties must be set: 106.Bl -tag -width ".Va compatible" 107.It Va compatible 108Must always be set to "dallas,ds1307" or "maxim,ds1307". 109.It Va reg 110The i2c address of 111.Nm . 112The default address for 113.Nm 114is 0xd0. 115.El 116.Sh SEE ALSO 117.Xr fdt 4 , 118.Xr iic 4 , 119.Xr iicbus 4 , 120.Xr sysctl 8 121.Sh HISTORY 122The 123.Nm 124driver first appeared in 125.Fx 11.0 . 126.Sh AUTHORS 127.An -nosplit 128The 129.Nm 130driver and this manual page were written by 131.An Luiz Otavio O Souza Aq Mt loos@FreeBSD.org . 132