It’s really hard to overstate how awesome ESP8266 development boards like the Wemos D1 Mini really are. For literally a couple of dollars you can get a decently powerful Wi-Fi enabled microco… ...

This pin is on the rear of the ESP8266 module, and on many development boards, it isn’t even connected. ... In Circuit Programming is still my favorite, and you only need 4 pins (3.3V, TX, ...