esptool

TLDR

Flash firmware

$ esptool.py --port [/dev/ttyUSB0] write_flash 0x00000 [firmware.bin]

Read chip information

$ esptool.py --port [/dev/ttyUSB0] chip_id

Erase flash memory

$ esptool.py --port [/dev/ttyUSB0] erase_flash

Read flash to file

$ esptool.py --port [/dev/ttyUSB0] read_flash 0 0x400000 [backup.bin]

Flash at specific baud rate

$ esptool.py --port [/dev/ttyUSB0] --baud [921600] write_flash 0x0 [firmware.bin]

Verify flash contents

$ esptool.py --port [/dev/ttyUSB0] verify_flash 0x0 [firmware.bin]

SYNOPSIS

esptool.py [options] command [args]

esptool.py is the official tool for flashing firmware to Espressif chips (ESP8266, ESP32, ESP32-S2, etc.). It communicates over serial to read, write, and verify flash memory.
The tool is essential for ESP32/ESP8266 development, used to upload Arduino sketches, MicroPython, ESPHome, and other firmware. It auto-detects chip type and flash parameters in most cases.

PARAMETERS

--port port

Serial port device.

--baud rate

Baud rate (default 115200).

--chip name

Target chip: esp8266, esp32, etc.

chip_id

Read chip ID.

flash_id

Read flash chip ID.

read_mac

Read MAC address.

write_flash addr file

Write binary to flash at address.

read_flash addr size file

Read flash contents.

erase_flash

Erase entire flash.

erase_region addr size

Erase flash region.

verify_flash addr file

Verify flash contents.

CAVEATS

Requires Python and pyserial. Device must be in bootloader mode (GPIO0 low on boot, or auto-reset via RTS/DTR). Write permissions needed for serial port. Incorrect flash may brick device (recoverable via bootloader).

HISTORY

esptool.py was developed by Espressif Systems as the official flashing utility for their ESP8266 and ESP32 series of WiFi/Bluetooth microcontrollers. It's open source and actively maintained as part of the ESP-IDF framework.