ESP32 Forum

Hi all,

I just figured out the way how to program ESP32-C3-WROOM-02 without interacting with BOOT and EN. In the picture below, the BOOT signal started to be held to LOW around 5ms after the EN signal went to HIGH, so ESP32 cannot enter boot mode.
In the ESP32-C3-WROOM-02 datasheet, the minimum hold time for the BOOT signal is 3ms when the EN signal starts to be HIGH. I think that means BOOT has to be LOW within 3ms after EN goes HIGH. However, as can be seen, the BOOT only started to be LOW 5ms after.

The solution to this is to change the 10k resistor input to the EN pin to a 47k resistor to make EN go HIGH after the BOOT is held to LOW. This solution was tested on 4 different machines and ESP32 was able to be programmed in all machines.

Though that change might be working for you. I see the EN signal toggling many times in a short period. It should not be doing that.
The typical fix is to put a 0.1uf cap from EN to GND, along with a 10k to 3.3v.

username wrote: ↑

Thu Mar 30, 2023 11:37 am

Though that change might be working for you. I see the EN signal toggling many times in a short period. It should not be doing that.
The typical fix is to put a 0.1uf cap from EN to GND, along with a 10k to 3.3v.

That could be because you're viewing the signal through the lens of a LA dump. The real, analog signal probably ramps up slowly but has some noise super-imposed, which after quantizing it to an on/off signal (like the LA does) looks like this.