ESP32 Forum

Hello,

I developed a board that contains esp32, 12v to 5V and 3.3V source(MP1584EN), st232c and DS1307. The PCBs are identical but for those with wroom-32U when using external power, UART0 no longer works properly. Some strange signs and sometimes truncated debug messages appear in the debug window. If I power the board through the USB adapter (5V) the messages come correctly. If I want to program the wroom-32U board and use external power, I can't program. If I use the power from the USB-TTL adapter it is OK.
On wroom-32 boards, debug messages appear correctly and can be programmed no matter what power source I use.
I use the same USB-TTL adapter in all tests.
When I use the board power supply, I disconnect the 5V wire from the USB-TTL adapter.
What is the difference between WROOM-32 and WROOM-32U and how can I solve the problem because I will only use WROOM-32U?
Thank you

Are you sure you connected the grounds togethet?

All the connections, all the cables are the same but different behaviors.

Well, there is not much difference between the ESP32-wroom-32 and esp-32-wroom-U, they're later revisions iirc but the basic schematic didn't change. Are you sure that there isn't something different between the PCBs, as in a bridged solder connection, or a solder connection that didn't take? Can you perhaps share schematics?

I attached the schematic from where I started. I don't use USB to UART on board and I use another Power supply from 12V to 5V (MP1584) and a LDO from 5v to 3.3V. All the PCBs are the same and all the components was planted on the line.

Not sure exactly why it would give problems, and extremely not sure why on a 32U but not on a 32, but I'd suspect the logic around D1/D3. If any, you're pulling up an ESP32 pin to 5V (via R35), which is out of spec. Can you check if removing R35/R40 and shorting D1/D3 still gives you the issue?

On my PCB I don't use the USB to UART from schematic. I connect an USB to TTL adaptor like this:
TX - GPIO1
RX - GPIO3
RST - ESP_EN
GND - GND + GPIO0

Clear. Do you still have the on-board USB-to-serial chip connected or did that get removed in the design?

The USB-to-serial chip was removed from board