Lowest of low power

[wevets]

I'm creating an app that will run under battery power and will be running the ULP in deep sleep most of the time, waking up periodically to report changes in sensor status via HTTP. If no changes in sensor status occur over long periods, a heartbeat report is sent to the back end occasionally to let the back end know that the device is still healthy. Lack of receipt of heartbeats at the back end signals the need for a maintenance visit.
If a fault occurs that prevents sending even heartbeats, let alone sensor status report, I'd like to be able to put the device into the lowest power state possible to preserve the battery for happier times. One way to do this would be to go into deep sleep running the ULP on it's quiescent timer for long periods.
Alternatively, is there a way for software to halt the system completely so that it consumes no power at all?

[ESP_Sprite]

You can go into deep sleep with no wake-up source configured and the ULP disabled; that should give you the lowest power use attainable by software.

[wevets]

Thanks for this. I'll implement it.