My board wouldn't boot, why?

[szabiaura]

I built a board hosting a ESP32-WROOM-32D module. After assembling, I just can't get it to do anything. Schematics are according to the datasheet. Here's what I checked:

• pin 1 (GND) is low
• pin 2 (3V3) is high (3.24V)
• pin 3 (EN) is high
• pin 14 (MTDI/GPIO12) is low
• pin 26 (GPIO0) is low to enter download mode for flashing initial firmware
• tried swapping TX/RX; the serial adapter works for sure
• power supply not shorted, the board takes about 10 mA

Yet:

Code: Select all

$ idf.py flash
Executing action: flash
Choosing default port b'/dev/ttyUSB0' (use '-p PORT' option to set a specific serial port)
Running ninja in directory /home/szabi/Documents/ledbridge/eclipse-workspace/8k_firmware/build
Executing "ninja flash"...
[1/4] Performing build step for 'bootloader'
ninja: no work to do.
[1/2] cd /home/szabi/esp/esp-idf/components/esptool_py && /home/szabi/.espressif/to..._firmware/build" -P /home/szabi/esp/esp-idf/components/esptool_py/run_esptool.cmake
esptool.py --chip esp32 -p /dev/ttyUSB0 -b 460800 --before=default_reset --after=hard_reset write_flash --flash_mode dio --flash_freq 40m --flash_size 4MB 0x8000 partition_table/partition-table.bin 0x1000 bootloader/bootloader.bin 0x10000 LEDBridge8KFirmware.bin
esptool.py v3.0-dev
Serial port /dev/ttyUSB0
Connecting........_____....._____....._____....._____....._____....._____....._____

A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
CMake Error at run_cmd.cmake:14 (message):
  esptool.py failed
Call Stack (most recent call first):
  run_esptool.cmake:21 (include)


FAILED: CMakeFiles/flash 
cd /home/szabi/esp/esp-idf/components/esptool_py && /home/szabi/.espressif/tools/cmake/3.16.4/bin/cmake -D IDF_PATH="/home/szabi/esp/esp-idf" -D ESPTOOLPY="/home/szabi/.espressif/python_env/idf4.2_py3.8_env/bin/python /home/szabi/esp/esp-idf/components/esptool_py/esptool/esptool.py --chip esp32" -D ESPTOOL_ARGS="--before=default_reset --after=hard_reset write_flash @flash_args" -D WORKING_DIRECTORY="/home/szabi/Documents/ledbridge/eclipse-workspace/8k_firmware/build" -P /home/szabi/esp/esp-idf/components/esptool_py/run_esptool.cmake
ninja: build stopped: subcommand failed.
ninja failed with exit code 1

This is the second board that I assembled, the other one does the same. I appreciate any ideas what else to check.

[szabiaura]

The solution is to pull EN low momentarily. This boots up the board into download mode.

How to make sure the board boots up without intervention after power is applied?

[becorey]

Most boards have either a physical button for EN and GPIO0, or they have an auto flash circuit using the DTR and RTS signals from the usb to serial chip