In order to use the ESP-01 Wi-Fi relay module, a programmer/programming adapter is required to program the ESP-01 module (see below). Also it is pretty easy to make your own programmer, or you can ...

Someone has invented a way to add Wi-Fi to a standard Arduino Uno, by proposing a module that drops into the DIL socket normally reserved for the ATmega328 – it will not work with Unos that have a ...