ESP32 Forum

Posted: **Wed Apr 19, 2023 6:01 pm**

Hello.

Is there a way to enter bootloader/download mode by calling a certain function in the user app?
For example, I'm aware of a function

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esp_restart()

which will simply reset CPU and it will boot back to the user app.
But what I need is a another function or a piece of code that resets CPU and makes so that it wouldn't jump to the user app and instead would stay in the bootloader.
I searched, but couldn't find any information on that. I tried configuring GPIO9 strapping pin as output, writing 0 to it and calling esp_restart() function, but that didn't work, probably because strapping pins are not sampled after software reset.

Posted: **Thu Apr 20, 2023 2:48 am**

Probably. Note that this register is normally intended for DWC-OTG use, and as the C3 does not have this, I'm not sure if we tested the functionality there, but you can try the following:

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REG_WRITE(RTC_CNTL_OPTION1_REG, RTC_CNTL_FORCE_DOWNLOAD_BOOT);
esp_restart();

Posted: **Thu Apr 20, 2023 4:45 am**

That worked, thank you.

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