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DS3231(4) FreeBSD Kernel Interfaces Manual DS3231(4)
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
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>.
FreeBSD 14.2-RELEASE February 12, 2016 FreeBSD 14.2-RELEASE