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NAMEds3231 - Extremely Accurate i2c-integrated RTC/TCXO/Crystal
SYNOPSISdevice iic device iicbus device ds3231
DESCRIPTIONThe sysctl Cm net.inet.tcp.syncookies 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 sysctl Cm net.inet.tcp.syncookies 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
- The read-only value of the current temperature read by the RTC.
- 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.
- 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.
- 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.
- 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 sysctl Cm net.inet.tcp.syncookies datasheet for more details.
On a device.hints5 based system, such as MIPS these values are configurable for :
- The iicbus(4) that the sysctl Cm net.inet.tcp.syncookies is connected to.
- The 8-bit i2c address of . The default 8-bit address for sysctl Cm net.inet.tcp.syncookies is 0xd0.
On a FDT(4) based system the following properties must be set:
- Must always be set to "maxim,ds3231".
- The 7-bit i2c address of . The default 7-bit address for sysctl Cm net.inet.tcp.syncookies is 0x68.