Now you have a barebones ESP-01 programming adapter ready to work with Arduino IDE. The next step is to start your own experiments with ESP-01. For examples, the Arduino core for ESP8266 comes with ...

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.

It turns out that there are different types of flash used with the ESP8266, and the correct programming mode must be selected for a given hardware setup.