NAME

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

SYNOPSIS

       device iic
       device iicbus
       device ds3231

DESCRIPTION

       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.

SEE ALSO

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

HISTORY

       The ds3231 driver first appeared in FreeBSD 11.0.

AUTHORS

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

Debian                                          February 12, 2016                                      DS3231(4)