Provided by: freebsd-manpages_12.2-1_all bug


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


     device iic
     device iicbus
     device ds3231


     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.

                                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:    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.


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


     The ds3231 driver first appeared in FreeBSD 11.0.


     The ds3231 driver and this manual page were written by Luiz Otavio O Souza