ESP32 Forum

Hi.
We have a pcb made with a ESP32-wroom-32UE
The RXD0(34) and TXD0(35) have been connected to a pin header, so we can connect UART,
We have a USB TTL we connect the GND, TX and RX
I can read the chip without any problem, but when we try to write/upload, It can connect

esptool.py v3.0-dev
Serial port COM9
Connecting........_____....._____....._____....._____....._____....._____.....____An error occurred while uploading the sketch
_

A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header

We are new to ESP32 in this fashion with a custom pcb board
I have uploaded sketch to NodeMCU dev boards with a onboard usb interface without any problems.

My fear is that the developer of the pcb board, have not attached or forgotten something so we can upload a sketch simply and easy with the UART

Hope someone can shed some light on this

Hi,

Can you share the schematics?

You need to pull GPIO0 low and then reset the ESP32 by pulling EN low momentarily. Normally a devboard has functionality like that built-in controlled by the USB-serial chips DSR/DTR pin, but if your PCB does not have that you need to do it manually.