At the heart of the ESP-01 module is the ESP8266 chip with at least two boot modes — the normal mode and the programming/flash mode. The latter refers to uploading any software (or firmware) to the ...

Beyond the 3D printed holder for the pogo pins, this programmer uses a FTDI USB-to-serial adapter, a couple passive components to smooth out the power going into the chip, and a couple buttons.

[Pete] was building a hot tub controller, using a WEMOS board based on the venerable ESP8266. After assembly, the board was plugged into USB and [Pete] hit the flash button. No dice. Investigation … ...