Hi everyone,

I'm designing my first PCB with an ESP32-S3-WROOM-1 and a CH340C USB-to-UART converter, but I can't flash the ESP32 and I can't figure out what is wrong.

When I connect the PCB to my PC, COM10 appears correctly and disappears when I unplug the board.

esptool.js gives me this error:

Serial port WebSerial VendorID 0x067b ProductID 0x2303

Connecting...

Error: Failed to connect with the device

What I have already checked:

The IC on the PCB is physically marked CH340C

COM10 appears/disappears when I connect/disconnect this PCB

3.3 V power rail is present

When I press SW1 (EN/reset), TP1/EN goes to 0 V

When I press SW2 (BOOT/GPIO0), TP2/GPIO0 goes to 0 V

TX/RX continuity between the CH340C and ESP32-S3 is good

TX/RX are crossed: CH340 TX → ESP RX and CH340 RX ← ESP TX

I also tried manually entering download mode by holding GPIO0 low while resetting EN, but esptool still cannot connect

One thing I find strange is that WebSerial reports VID 067B / PID 2303, even though the chip on my board is marked CH340C.

I've attached my full schematic and PCB layout.

Could someone please check if there is something wrong with my CH340C circuit, DTR/RTS auto-reset circuit, EN/GPIO0 circuit, ESP32-S3 connections, or PCB layout?

I'm still learning PCB design, so I may have missed something obvious. Any help would be greatly appreciated 🥺

Je mettrais les deux images que tu m'as envoyées : d'abord le schéma, puis le PCB. Le détail 067B:2303 alors que la puce est marquée CH340C mérite absolument d'être conservé dans le post, parce que quelqu'un sur r/KiCad ou r/esp32 peut reconnaître immédiatement ce comportement.

ESP32-S3-WROOM-1 + CH340C PCB: COM port works but esptool can't connect – what did I do wrong?