Wake time from deep sleep optimization

[IOTrav]

Hi Everyone,

First thank you for taking the time to read this post.

I am working on a battery powered project which utilizes the ESP32 as the main processor. I only use WiFi for soft AP for user configuration of the device.

Essentially in normal run operation the ESP32 wakes up based on a sleep time interval, reads an I2C sensor, then (if need be) sends a transmission over a long range wireless module connected to the ESP32 via UART, then goes back to deep sleep.

My run time code on the ESP32 only takes around 55mS to execute(reading the sensor, evaluating, and sending the transmission over the long range wireless module). My main issue, which is drastically reducing my estimated battery life, is the 270mS "boot" time of the ESP32 module. I have read every article I can find on this subject but nothing seems to make a meaningful impact on the ESP 32 boot time from deep sleep(270mS). I have flash mode set to qio, flash speed set to 80mHz, and cpu frequency set to 240mHz.

What is the best boot time I can hope for? Also for reference I am using a WROOM32D.

Thank you

[WiFive]

There is the option to do everything from ULP code, there is wake stub, and this https://github.com/espressif/esp-idf/pull/3304

Probably more tweaks are possible.