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

Projects General Guidance
1

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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2

Where is U5, U3 etc?
Looks like all the USB_n connections are tied together.
None of the grounds are connected.

There is no RX/TX.

3

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This is the whole schematic. I figured I'd just upload the upper half, since the lower one is not really related to the communication.
The TX/RX Pins are pin number 11 and 12 on the ESP and they are connected to J10 which I then connected to a working ESP32 Devkit V4.
I have a 3.3V Layer and a GND Layer since its a 4-Layer PCB. So the GND and 3.3V of the devices are normally just connected to specific Layer through vias.

4

Read this and you should see where you went wrong

5

This is a guide to flash the ESP32.
However, my problem is, that my physical connection to the device seems to be faulty. I just can't figure out what the problem is, since I precisely followed the instructions on the datasheet of the ESP32 C3 Wroom 02 and USBLC6. The flashing would be the next step, when I have a good connection, which is not connecting and deconnecting every second.

6

Yes.
You have no BOOT button, so there is no way you can flash the ESP.

7

Yes I'm aware of that. I would do it the first time just by holding LOW-cables to the GPIO9. EN is connected via a button to GND.
However, all this can only happen, if I have a stable, working connection to the laptop, so the laptop can detect the ESP as serial device. And this is the part, which is not working. The reason must be some wrong links on the USB connector or missing resistors or something like this, but I don't understand what.

8

Doing that is somewhat questionable.
Are you sure GPIO9 is held low while the reset goes from low to high?
Are you using a good USB-C cable?

9

Are you sure U4 is on the right way?

10

I desoldered U4 and soldered the connections directly, with the same result.
USB cable works for connections with other controllers just fine.
Yes GPIO9 ist held low, but anyway, it should send me a header or something before I go into flash mode.

11

Well there could be several other things that are wrong, bad solder joint, short or open circuit somewhere, wrong resistor/capacitor value, no 3.3V...