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esptool

Flash and inspect ESP8266 and ESP32 chips over their serial bootloader

What it does

Talks to the ROM bootloader on Espressif ESP8266 and ESP32 chips over a serial link: writes firmware images, reads them back, erases flash, and reports the chip revision, MAC address and flash size.

Why you would want it

It is how anything ESP32-based gets new firmware from Linux rather than from a browser-based flasher, which matters when the board is in front of you and the network is not. esptool chip_id is also the fastest way to find out what a board actually is when the silkscreen is ambiguous, which is frequently how a device identification starts.

Before it will work

Membership of the dialout group, and a board in bootloader mode. Many boards enter it automatically via DTR/RTS; some need BOOT held while RESET is tapped. Group membership does not apply to a session already open.

How it installs

  • apt: esptool

Known problems

It will happily write an image intended for a different chip and leave the board unresponsive until reflashed — recoverable, but alarming the first time. A board whose native USB stack is provided by its own firmware disappears from /dev while being reflashed; that is expected. ModemManager grabbing the port for twenty seconds after plug-in looks exactly like a dead board.

Keeping it current

  • probe: apt policy
  • strategy: apt_upgrade

Source: catalog/packages/esptool.yaml