Artekit Labs posts a general guide about microcontroller inputs/outputs, commonly called GPIOs. It is an excellent primer to knowing how a microcontroller handles input and output connections.
There is something in common among all the microcontrollers you can find in the market: they have pins. While some pins have a predefined function, like the RESET pin or serial communication RX/TX pins, some others can be used as a General Purpose Input/Output (GPIO).
As the name indicates purpose of this kind of pin is generic, as they don’t perform any specific function. They are there for you to configure them and use them as inputs or outputs.
In this guide we will learn what a GPIO does and the different ways you can configure and use them. The text is oriented to embedded developers and contains basic and to-the-point explanations, as a general reference.
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.