ESP32 Forum

Hi All,

I designed a new custom PCB with ESP32-U4WDH Chipset and I tried to flash the code from Arduino IDE and it seems not connecting and showing the error,
"A fatal error occurred: Failed to connect to ESP32: No serial data received.
For troubleshooting steps visit: https://docs.espressif.com/projects/esp ... oting.html
Failed uploading: uploading error: exit status 2"

I'm afraid of whether the ESP chipsets come with a bootloader or not. Do I need to install the bootloader via JTAG or some source?

Please help. Thanks in advance.

ESP chips come with a bootloader from the factory embedded in non-modifyable ROM. You both cannot and do not need to install your own bootloader to program them.

Hi Thank you for the reply,

If it comes with the bootloader, Im wondering why its not working with Arduino IDE?
Please go through the attached schematic images for your reference.

- You need a reset RC network for the ESP32 to function correctly. Add an 1uF capacitor between CHIP_PU and GND and together with R3 it should suffice as the RC network.
- You're not trying to power the ESP32 off the CP2102, are you? If so, that chip can only provide a very small amount of current, not nearly enough to power the ESP32. You need some kind of LDO or other regulator capable of providing 3.3V at at least 600mA, as per the ESP32 datasheet.
- With all that fixed, try opening a serial terminal program on the serial port. Reset the ESP32 by manually pulling CHIP_PU low. Do you get any text on the serial terminal?
- If not, measure voltages: at the 3.3V rail, at the CHIP_PU pin. If you have a scope, see if you can see a 40MHz signal at the pins of Y1.

I Bought ESP Mini 1 Dev kit and replaced the ESP32-U4wD with mine. And it worked. Then I understood that the issue is with my PCB.
Then I flashed a sample serial print code and fit it back into my PCB. And checked the UART data, Im getting the serial data ,I can see in my terminal. So the MCU is working in my PCB. Only the flashing is not working. I checked the Reset and GPIO0, but both tracks are perfect and the connections match.
Any other things to be checked?

The code is running means,
>crystal is fine
>MCU working properly
>Transmitter Receiver function working

Only flashing is the issue