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Manual Pages  — DS1307


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



device iic device iicbus device ds1307


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
  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.
  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.
  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:
  The iicbus(4) that the ds1307 is connected to.
  The i2c address of ds1307.

On a FDT(4) based system the following properties must be set:
  Must always be set to "dallas,ds1307" or "maxim,ds1307".
  The i2c address of ds1307. The default address for ds1307 is 0xd0.


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


The ds1307 driver first appeared in FreeBSD 11.0 .


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

DS1307 (4) March 7, 2015

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