DS3231 Time Source

The ds3231 time platform keeps the system clock from a DS3231 real-time clock, so the device knows the time right after boot, even without a network connection.

Set up the ds3231 hub (and the I²C bus it needs) first.

# Example configuration entry
time:
  - platform: ds3231
    id: ds3231_time

Configuration Variables

• ds3231_id (Optional, ID): The ID of the ds3231 hub to use when more than one is configured.
• All other options from Base Time Configuration.

The RTC holds UTC time. If the chip’s oscillator was stopped (for example because the backup battery is empty), the stored time is invalid and is not used until a new time has been written. The oscillator_stopped binary sensor shows this state.

ds3231.write_time Action

This Action writes the current system time to the RTC and clears the oscillator-stop flag.

NOTE

The RTC is not written unless this action is triggered explicitly.

on_...:
  - ds3231.write_time

  # in case you need to specify the time id
  - ds3231.write_time:
      id: ds3231_time

ds3231.read_time Action

This Action sets the system time from the RTC.

NOTE

The RTC is read automatically every update_interval (15 minutes by default). This action can be used to trigger additional synchronizations.

on_...:
  - ds3231.read_time

  # in case you need to specify the time id
  - ds3231.read_time:
      id: ds3231_time

Full Configuration Example

Read the RTC once at boot, and update it whenever another time source has synchronized:

esphome:
  on_boot:
    then:
      - ds3231.read_time:

ds3231:

time:
  - platform: ds3231
    # the DS3231 is accurate to a few ppm, but repeated reads aren't needed
    # while a network time source is available
    update_interval: never
  - platform: homeassistant
    on_time_sync:
      then:
        - ds3231.write_time:

See Also

• DS3231 Real-Time Clock
• Time
• API Reference: ds3231/time/ds3231_time.h