Flashing

Use esptool.py for flashing.

Linux: esptool.py --port /dev/ttyUSB0 write_flash 0x0 firmware.bin

Windows: esptool.py --port COM1 write_flash 0x0 firmware.bin

With ESP32 it is a bit more complicated: esptool.py --chip esp32 --port /dev/ttyUSB0 --baud 460800 --before default_reset --after hard_reset write_flash -z --flash_mode dio --flash_freq 40m --flash_size detect 0x1000 bootloader.bin 0x8000 partitions.bin 0x10000 firmware.bin

Get the bootloader here: Arduino ESP32 bootloader The default bootloader is bootloader_dio_40m.bin