Flashing

When flashing is required, e.g. due to a brick or when flashing different firmware, the following steps can be achieved to reinstalled the official firmware.

The application and bootloader are not packed into a single binary, and thus need to be downloaded separately.

An USB-UART cable is needed, and a strong 3v3 power supply. Some USB cables do not supply enough, or not 3v3. Only DTR is mapped to the pinheader, not RTS, so an automatic reset is not possible.

1. Download the bootloaders but ignore/remove firmware.bin, it is replaced with the file from the next step
2. Download a pre-compiled firmware image
3. Connect the USB-UART cable to the pin-header
4. Optionally connect DTR pin if possible, otherwise pushing of the reset and boot buttons are needed in the next step
5. Assuming we are using ttyUSB0

esptool.py --chip esp32 --port /dev/ttyUSB0 --baud 921600 --before default_reset --after hard_reset write_flash --flash_mode dio --flash_freq keep --flash_size detect --compress \
0x1000 bootloader.bin \
0x8000 partitions.bin \
0xe000 boot_app0.bin \
0x10000 nrgitho-v<version>.bin

1. Optionally disconnect the DTR pin
2. Press reset