wake up by ulp from deep sleep?

[JunfengJia]

My application is power-hungry, so I’m looking for a way to put the ESP32 into deep sleep and wake it up using a pin or some other logic running in the ULP. Any ideas?

[kasperl]

@JunfengJia With a little bit of luck, you may not need the ULP to trigger this. Here is an example of using a GPIO pin trigger for waking up from deep sleep: https://github.com/toitlang/toit/blob/master/examples/triggers/gpio.toit.

[JunfengJia]

Thanks a bunch, @kasperl! The GPIO works for me in some cases, like when the user presses a button. I’ll do more testing for other scenarios. I also created a small ulp + c program that works for the basic idea, but I’m not sure if it can also work with ULP+toit. ULP, check condition, if true, wakeup esp32, then C code do some work, then deep sleep, and ULP checking again. Do you think there’s a way to do it in ULP + toit?

[floitsch]

We haven't implemented support for ULP yet.
There seems to be some interest in it, so I will try to bump its priority. Will probably still take a few weeks before I get to it.

Once implemented, your use case should be possible.

[JunfengJia]

Hey @floitsch, thanks for getting back to me! For now, I’ll use sleep/check as a solution. Thanks again for working on it! Please let me know once it's available for test, so I can improve my design.