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espressif / esp-idf

Espressif IoT Development Framework. Official development framework for Espressif SoCs.
Apache License 2.0
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power off: restart after brownout (IDFGH-2362) #4489

Open thedayu opened 4 years ago

thedayu commented 4 years ago

I am using esp32 to control LED, having a ISSUE during power off:

After cut off the power, because of the capacitor, It takes about 2 seconds for voltage to drop from 3.3v to 1v. Esp32 browns out and restarts 2 or 3 times during voltage dropping, which causes my LED to flash. Is there a way to stop esp32 to restart during power off?

thedayu commented 4 years ago

After disable brownout detection, it works. Is there a guarantee that during VCC voltage droping, esp32 turns off and does not restart. Saying, turn off @2.2v, and will not try to restart here?
I'm thinking that maybe WIFI requires more power and likely brings esp32 down, but restart procedure requires less power hence ESP32 goes up.

AloyseTech commented 4 years ago

You could try to handle the brown out reset at startup and wait ~2 sec. You can use rtc_get_reset_reason() to get the reset reason. It will return ESP_RST_BROWNOUT in case of a brown out detection.

costaud commented 4 years ago

Is it possible to add a diode in the circuit to make the voltage drop quickly ?

thedayu commented 4 years ago

You could try to handle the brown out reset at startup and wait ~2 sec. You can use rtc_get_reset_reason() to get the reset reason. It will return ESP_RST_BROWNOUT in case of a brown out detection.

Thanks for replay.

It will cause slow response of led. In fact, in order to bring pwm signal quicker, I put the ledc function into bootloader, to save 500ms boot time of RTOS. I cannot wait the 2 seconds.

New update, after disable brownout detection, it is kind of working. During my test, my led flashes one time of around 30 times of power off. It appears that there is no guarantee?

thedayu commented 4 years ago

Is it possible to add a diode in the circuit to make the voltage drop quickly ?

Trying to refine the circuit, but how quick is quick enough..?