ESP32 Forum

Hi,

Lately i have been busy with integrating some ULP code and making that code wake up the main processor.
Until now it appears to be relatively straightforward but there are some things I am not 100% sure about.
First: a brief description of what my application needs to do:

• On initial start up: transfer the ULP binary to RTC memory: that works 100%.
  use "ulp_run" to start the ULP code after having set it up to re-run every 15 seconds.
  Once it has run 20 times, and gathered 20 data samples, it wakes up the main processor and performs a ULP HALT operation.
  The main processor copies the 20 samples and stores it in a dedicated NVS partition.

The only thing I am not 100% sure about is that after copying and storing the samples the main processor uses "ulp_run" again to restart the ULP code after 15 seconds just after having set the timer register again to 15 seconds.
According to the documentation "ulp_run" starts the timer and after the specified time it will run the ULP code again.
That leads me to the following questions:

• As the ULP coprocessor's 15 second action always uses "halt" to make it sleep for the best part of 15 seconds and uses "wake" and "halt" once every 5 minutes to wake up the main processor and stop its own operation. Won't the ULP code automatically execute again after 15 seconds with or without the use of "ulp_run" by the main processor by that time?
  is it possible that the ULP code is halted for as long as the main processor runs?
  If it does happen again after 15 seconds while the main processor is performing some lengthy task which takes more than 5 minutes ( e.g.: an OTA update ) will it try to wake up the main processor?
  If it does try and wakeup the main processor while it is still running what will happen then?
  Will the main processor simply ignore the wake up attempt?

All in all it works well but I would like to be sure about the items above so that I could build in some refinements in case the main processor has to perform lengthy tasks.

Any help much appreciated.

Hi,

It is my understanding that the ulp runs independently of the main cpu.

However I found that an ulp wakeup can interfere with the deepsleep wakeup timer.