NAME

     ds1307 — 64 x 8, serial, i2c real-time clock

SYNOPSIS

     device iic
     device iicbus
     device ds1307

DESCRIPTION

     The ds1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD)
     clock/calendar plus 56 bytes of NV SRAM.

     The ds1307 has a built-in power-sense circuit that detects power failures and automatically
     switches to the backup supply.  Timekeeping operation continues while the part operates from
     the backup supply.

     Access to ds1307 settings is made with the sysctl(8) interface:

     dev.ds1307.0.%desc: Maxim DS1307 RTC
     dev.ds1307.0.%driver: ds1307
     dev.ds1307.0.%location: addr=0xd0
     dev.ds1307.0.%pnpinfo: name=rtc compat=maxim,ds1307
     dev.ds1307.0.%parent: iicbus1
     dev.ds1307.0.sqwe: 1
     dev.ds1307.0.sqw_freq: 32768
     dev.ds1307.0.sqw_out: 0

     dev.ds1307.%d.sqwe      If set to 1, the SQW pin drives a square-wave of
                             dev.ds1307.%d.sqw_freq frequency.  If set to 0, the output level of
                             SQW pin is controlled by dev.ds1307.%d.sqw_out.

     dev.ds1307.%d.sqw_freq  Select the frequency of the SQW pin when the square-wave output is
                             enabled on dev.ds1307.%d.sqwe.  It can be set to 1, 4096, 8192 and
                             32768.

     dev.ds1307.%d.sqw_out   Set the output level of the SQW pin when dev.ds1307.%d.sqwe is set
                             to 0.

     Please check the ds1307 datasheet for more details.

     On a device.hints(5) based system, such as MIPS, these values are configurable for ds1307:

     hint.ds1307.%d.at    The iicbus(4) that the ds1307 is connected to.

     hint.ds1307.%d.addr  The i2c address of ds1307.

     On a FDT(4) based system the following properties must be set:

     compatible  Must always be set to "dallas,ds1307" or "maxim,ds1307".

     reg         The i2c address of ds1307.  The default address for ds1307 is 0xd0.

SEE ALSO

     fdt(4), iic(4), iicbus(4), sysctl(8)

HISTORY

     The ds1307 driver first appeared in FreeBSD 11.0.

AUTHORS

     The ds1307 driver and this manual page were written by Luiz Otavio O Souza
     <loos@FreeBSD.org>.