HTTPS and POST with ESP8266 WiFi
ESP8266 Arduino code that allows you to request web pages over either http or https, and also to POST to websites
Use the MCP23017 GPIO Port Expander to Add 16 IO Pins
MCP23017/MCP23008 port expanders add more GPIO pins using I2C which means you only need two wires to get 8, 16 or even more lines of IO
Neo6502 GPIO Input and Output
Neo6502 GPIO Input and Output for electronics programming in BASIC. How to light up and fade an LED, plus read a button as input.