USB-/ RX-TX-communication to ESP32 C3 Wroom 02

BBBJG123
Posts: 1
Joined: Wed Oct 08, 2025 1:36 pm

USB-/ RX-TX-communication to ESP32 C3 Wroom 02

Postby BBBJG123 » Wed Oct 08, 2025 1:45 pm

Hey,

I'm trying to design a PCB with a ESP32 C3 Wroom 02 Chip and a USB communication to it. Its already my second try and its just not working.

When I plug it into the computer there ist always a connection and after a second deconnecting and so on.

Even communication over RX/TX with a ESP32 Devkit V4 doesnt work, I don't even get some "alive" signal, when I lay EN on GND. I connected RX from C3 to TX from Devkit and vice versa and also powered the C3 with 3.3V from the Devkit and they share same ground.

I went over everything, asking ChatGPT, I just don't know further. Although there is some other stuff on the board (mainly a HX711 and power supply) the communication with the chip is my main issue.
The chip is powered and when I lay EN on GND, than I can see on the multimeter a change form 3.21V to 3.3V, but nothing else.

Hope somebody can help me.
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MicroController
Posts: 2672
Joined: Mon Oct 17, 2022 7:38 pm
Location: Europe, Germany

Re: USB-/ RX-TX-communication to ESP32 C3 Wroom 02

Postby MicroController » Wed Oct 08, 2025 7:32 pm

When I plug it into the computer there ist always a connection and after a second deconnecting and so on.
This is normal when the ESP has no firmware to run in flash yet. It activates USB, tries to boot, fails, restarts resetting USB in the process.

Pull down the BOOT strapping pin during power up/reset to enter the bootloader and be able to flash an initial firmware. This is also required when programming over serial, unless you also have the RTS/CTS signals connected in the right way.

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