Weird characters using ESP32 and CH340G

[alvaromarfer]

Hello everyone!

Right now I am working in a robotic project where I have to develop a educational robot that has to be programmed via USB straight from the PC. For that I developed a custom PCB whith a USB C connected to the CH340G and this one is connected to the TX and RX pins of the ESP32.

When I ordered this PCBs I got a sad surprise. Just half of them came working. With the ones that were okay you can upload a sketch whitout any problem so everything was okay. But the other half I only could read random characters from the serial terminal and wasn't able to upload any sketch.

At this point I am really stuck with the problem... First of all everything looks okay following the datasheets of the components, and why just half of it doesn't work?

Attached I included the schematic of the PCB and the serial communication when the board doesn't work.

The problem is not related with the bauds of the serial com, in case you were wondering

And I cannot change the CH340G because I already have a lot of robots working with this chip...

Any help will be very helpful. Thanks in advance!