I'm trying to re-flash an Athom plug (bought pre-flashed with HomeKit firmware) using FTDI adapter.

Shown here is the exact ESP8285 (different plug sub-model). AFAIK ESP8285 is a similar MCU to ESP8266 regarding pulling down GPIO0 to GND prior to powering the MCU in order enable uploading a new sketch/firmware.

When doing so- it flahing failed. 2 other method that I've tried, failed:

  1. This link shows that RST should me pulled down to GND.

  2. This link explains that GPIO0 should be help entire time (from powering until end of flashing).

1 Answer 1


The correct procedure is:

  1. Power up your ESP programming setup, and connect it to your PC.

  2. Press and hold the Reset button, and then press and hold the Flash button (pull GPIO0 low/GND).

  3. Release the Reset button and then release the Flash button.

  4. Click the START button in the flash download tool GUI window.

The boot procedure for ESP8266:

When a ESP8266 starts/or is reset it start to check the GPIO0 status, that decides if it should start the program or get into serial bootloader mode (Flash mode).


  • what you described is a normal ESP8266 upload (at least the pulling down GPIO0 to GND is familiar). Beside that, which I did, it failed ( as described in my question). is there something that I did wrong ?
    – guyd
    Oct 13, 2023 at 8:16

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