I think I have found a way to verify that the ULP is actually going to wake up and run its program. The ULP Coprocessor programming API Guide has this to say near the end of the https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/ulp.html#esp32-ulp-program-flow section: The progr...

I have since found my own workaround for this unpopular problem. After reset, I check the return of esp_reset_reason(), and if it is ESP_RST_WDT, I do a second check to see if the RTC memory used by the ULP is coherent. If so, I assume it was a normal wake, and not a watchdog reset. Interestingly, t...

We are having a problem with the ESP32 waking from deep sleep. We have multiple systems that have been reliably going into deepsleep, performing several I2C sensor readings, and then waking the main cpu to report the readings over wifi. These systems have had reliable up-times of weeks to months. We...

Bump, please.

Before waking up the ESP32 ULP from deep sleep, the documentation explains how and why to check the RTC_CNTL_RDY_FOR_WAKEUP bit before executing the wake instruction. None of the documentation explains what causes that bit to be set or cleared. I am using the ULP in a battery powered system to do pe...