ds3231 — Extremely Accurate i2c-integrated RTC/TCXO/Crystal

       The ds3231 driver and this manual page were written by Luiz Otavio O Souza <loos@FreeBSD.org>.

Debian                                          February 12, 2016                                      DS3231(4)

       The  ds3231  is  a  low-cost, extremely accurate I2C realtime clock (RTC) with an integrated temperature-
       compensated crystal oscillator (TCXO) and crystal.

       The device incorporates a battery input and maintains accurate timekeeping when main power to the  device
       is interrupted.

       Access to ds3231 data is made with the sysctl(8) interface:

       dev.ds3231.0.%desc: Maxim DS3231 RTC
       dev.ds3231.0.%driver: ds3231
       dev.ds3231.0.%location: addr=0xd0
       dev.ds3231.0.%pnpinfo: name=rtc compat=maxim,ds3231
       dev.ds3231.0.%parent: iicbus1
       dev.ds3231.0.temperature: 23.2C
       dev.ds3231.0.temp_conv: 0
       dev.ds3231.0.bbsqw: 0
       dev.ds3231.0.sqw_freq: 8192
       dev.ds3231.0.sqw_mode: interrupt
       dev.ds3231.0.32khz_enable: 1

       dev.ds3231.%d.temperature  The read-only value of the current temperature read by the RTC.

       dev.ds3231.%d.temp_conv    Start  a new temperature conversion.  When read as 1, a temperature conversion
                                  is in progress.  When read as 0 and then set to 1, a temperature conversion is
                                  started.  The temperature conversion runs automatically on power up  and  once
                                  every 64 seconds afterward.

       dev.ds3231.%d.bbsqw        If  set  to 1 and dev.ds3231.%d.sqw_mode is set to square-wave, battery-backed
                                  square-wave output is enabled.  If set to 0, the SQW pin will be set  to  high
                                  impendance when the RTC is being powered by battery.

       dev.ds3231.%d.sqw_freq     Select  the frequency of the SQW pin when the square-wave output is enabled on
                                  dev.ds3231.%d.sqw_mode.  It can be set to 1, 1024, 4096, and 8192.

       dev.ds3231.%d.sqw_mode     Set the operation mode for  the  SQW  pin.   It  can  be  set  to  'interrupt'
                                  (default)  or  'square-wave'.   In  interrupt  mode,  the  SQW  pin is used to
                                  generate interrupts for the RTC alarms.  In  square-wave  mode,  the  SQW  pin
                                  drives a square-wave of dev.ds3231.%d.sqw_freq frequency.

       dev.ds3231.%d.32khz_enable
                                  Enable the 32kHz output.

       Please check the ds3231 datasheet for more details.

       On a device.hints(5) based system, such as MIPS, these values are configurable for ds3231:

       hint.ds3231.%d.at    The iicbus(4) that the ds3231 is connected to.

       hint.ds3231.%d.addr  The 8-bit i2c address of ds3231.  The default 8-bit address for ds3231 is 0xd0.

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

       compatible  Must always be set to "maxim,ds3231".

       reg         The 7-bit i2c address of ds3231.  The default 7-bit address for ds3231 is 0x68.

       The ds3231 driver first appeared in FreeBSD 11.0.

       ds3231 — Extremely Accurate i2c-integrated RTC/TCXO/Crystal

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

deviceiicdeviceiicbusdeviceds3231