Good resource

In this article we will take a closer look at how to effectively low-pass filter a PWM signal into an analog voltage.

The digital inputs and outputs (digital I/O) on the Arduino are what allow you to connect sensors, actuators, and other ICs to the Arduino . Learning how to use the inputs and outputs will allow you to use the Arduino to do some really useful things, such as reading switch inputs, lighting indicators, and controlling relay outputs.

When you have multiple LEDs with a common anode or common cathode, can you use just one current-limiting resistor? Let’s take a look.