I have built a custom circuit board using the ESP32-C3-MINI-1-H4 module (datasheet).
Here is a schematic:
I have the GND, Tx, and Rx lines hooked up to an Arduino Uno without the ATmega. The 3.3 V comes from an external power supply.
I have successfully put the chip into download mode (as shown from the serial output below).
Build:Feb 7 2021
rst:0x1 (POWERON),boot:0x5 (DOWNLOAD(USB/UART0/1))
waiting for download
I attempted to upload an example sketch using the following settings (Arduino IDE).
I held down the reset button (S4) until the Rx light on the Uno started flashing.
It works about 5% of the time, but 95% of the time it ends in this:
A fatal error occurred: Failed to connect to ESP32-C3: No serial data received.
I'm not sure how that is possible, as the serial data appears on the oscilloscope, and it is clearly in download mode as shown by the serial output.
I have tried removing the voltage divider from the RX line, but that didn't help. Is there any way to make uploading more consistent?