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DS3231(4)		 BSD Kernel Interfaces Manual		     DS3231(4)

     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

     The device	incorporates a battery input and maintains accurate timekeep-
     ing 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 tempera-
				ture 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

				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 config-
     urable 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 <>.

BSD			       February	12, 2016			   BSD


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