ESP32 Forum

Hello everyone,
I bought a bunch of esp-wroom-32u from mouser to use them on my project. I made a cp2102-based programmer too with s8050 npn transistor with a connector to hook it up easily to my main pcb with esp32 attached.
I soldered it perfectly along with:

Gpio0 pulled up by 10k
EN pulled up by 10k + 100nF capacitor
Gpio2 pulled down by 10k
100uF main voltage source decoupling cap

Connecting and powering it through programmer it measures 3V3 correctly on power pins but if I try to use esptool.py it just says connect...___... Until error. Even a brand new esp32 module with no bootloader or anything on it should connect if I try a polling command on esptool right?
I thought it was a fault in the programmer, so I connected it to a working doit breakout board using Gpio0, enable, rx, TX, 3v3 and gnd pins and it works just fine. Programmer is OK.
This is why I started to think the esp32 module itself is the problem and it's fried somehow. Any hints?

You are right in that an ESP32 should respond to download mode regardless of what's in the flash. Perhaps you can use a serial terminal (at 115200 baud) to see what the ESP32 spits out when you press the reset button? That may help debugging the issue.

ESP_Sprite wrote: ↑

Tue Jan 19, 2021 1:33 am

You are right in that an ESP32 should respond to download mode regardless of what's in the flash. Perhaps you can use a serial terminal (at 115200 baud) to see what the ESP32 spits out when you press the reset button? That may help debugging the issue.

Thank you for your reply. I did this test already using a jumper via EN and GND but output is mute. Anyways I don't think it could help that much since the working breakout board is also mute over serial when I press reset. Is this sufficient to say the wroom module is probably fried and spend time building another pcb (maybe with just minimal components to be able to flash) ? RXTX_prog<->TXRX_esp32 is correctly wired too.
If I'm right the minimal setup for programming should be just 10k pullup on the EN pin + 100nF capacitor and required pin are gpio0, tx, rx, en, 3v3 and gnd? Are gpio0 pullup and gpio2 pulldown strictly required?

There's an internal pull-up on IO0 and pulldown on IO2, no need for external resistors.
https://www.esp32.com/viewtopic.php?t=5970

becorey wrote: ↑

Tue Jan 19, 2021 3:27 pm

There's an internal pull-up on IO0 and pulldown on IO2, no need for external resistors.
https://www.esp32.com/viewtopic.php?t=5970

Gotcha, I did that just because many esp32-based breakout boards include that resistors. Tomorrow I'll try with a new wroom module and let you know if the first one was just fried.