RX8111 Event Timestamp

The rx8111 text sensor publishes timestamps captured by the EVIN input of an RX8111 real-time clock. Configure that time component first.

text_sensor:
  - platform: rx8111
    name: "Event Timestamp"

Configuration Variables

• rx8111_id (Optional, ID): The RX8111 time component. Required when more than one RX8111 is configured. Only one timestamp text sensor is allowed per clock.
• timestamp_record_mode (Optional, string): Timestamp storage mode. Defaults to latest.
  • latest: Publish the latest captured record. A new event replaces the previous record.
  • stop_when_full: Store up to eight records; capture stops updating the buffer when it is full.
  • overwrite: Store the latest eight records, replacing the oldest when full.
• All other options from Text Sensor.

Capture and Publication

The text sensor enables EVIN capture independently of event_enabled, which controls the event interrupt and on_event automation. Configure event_level, evin_filter, and evin_pull on the time component to match the connected signal. With no explicit settings, capture uses an active-low input, no filter, and no internal pull. The RTC must contain trusted UTC time; timestamp capture does not set or synchronize its calendar.

The component preserves the internal timestamp-trigger settings in register 0x35. Records produced by previously enabled internal triggers can therefore also be published; the entity does not distinguish them from EVIN records.

Output Format

States use UTC ISO 8601 format, for example 2026-10-24T12:34:56.999Z, regardless of the time component’s timezone. Fractional seconds are truncated to milliseconds. Invalid BCD, impossible dates, and records whose captured oscillator-stop flag is set are skipped without replacing the last valid state. The supported calendar years are 2019–2099. When no records have been published, the entity has no state.

Without filtering, latest storage has a resolution of 1/1024 second and buffered storage has a resolution of 1/256 second. Enabling the hardware filter makes some low fractional bits unreliable, so three decimal places do not imply millisecond accuracy. Retained records may have been captured with a different filter setting, so their fractions are not masked using the current configuration.

Storage Modes and Event Loss

Choose the mode by how bursty the input is:

• latest: only the newest event per poll interval is kept. A second event before the next poll replaces the first.
• stop_when_full: up to eight unread records are kept. Events after the eighth are dropped until the records are read.
• overwrite: the newest eight records are kept. Further events replace the oldest unread records.

Buffered records are published oldest first. The entity state holds the last valid record, so use on_value to process each record.

Polling

Records are checked using the time component’s event_poll_interval (default 1s, minimum 500ms), even when update_interval: never disables periodic calendar reads. No separate timestamp polling loop is created.

In latest mode, each poll compares storage with the previous record without pausing capture. Only when the record has changed is capture paused and the record read again for publication. In buffered modes, capture is paused while the records are read and the buffer is cleared. Events during a pause are not captured. A longer poll interval means fewer pauses, but more chance that a newer record replaces an unread one in latest mode.

Acknowledging Events

Publication does not clear EVF or release /INT. Use rx8111.clear_event_flag explicitly after handling an event if acknowledgement is needed. Records are read whether or not EVF is set: in latest mode a changed record is published and an unchanged one is not published again, even after EVF is acknowledged.

Startup and Recovery

At startup, capture is paused, retained records are read in their previous storage format, and the requested mode is configured before capture resumes. Retained records are published once configuration succeeds.

A retained latest record is only published when the clock was not reset or stopped (POR, VLF, and XST all clear) and either EVF is set or capture was already enabled. Otherwise it only becomes the baseline for later comparisons. There is no persistent record of what was already published, so an acknowledged record may be published again after a host reboot. If capture was disabled and EVF cleared before the reboot, an unread latest record cannot be told apart from unused storage and is not recovered.

I²C failures set a warning and are retried by event polling, or at startup by up to three configuration attempts. Buffered records may be delivered again when clearing the buffer fails. If all three startup attempts fail, records that were fully read are still published once, so records already removed from the RTC are not lost. Capture can then stay disabled for the rest of that boot; fix the bus fault and reboot the host to retry.

NOTE

Records waiting for delivery are kept in RAM only, so they are lost on a host reset or power loss before publication. Publication also does not guarantee that a remote client received the state.

See Also

• RX8111 Time
• Text Sensor