A schematic of the Arduino
Now that we’ve run our code and lit the LED on the Arduino board, we’re going to attach our Arduino to a breadboard, build a circuit and run our ATG3_Blink sketch again. We want to learn how to control external components with our Arduino, not just light up an LED on the Arduino itself, so we must attach a breadboard to hold the components.
To run ATG3_Blink on the Arduino attached to a breadboard, we won’t need to make changes to our code. When we set pin 13 to HIGH in ATG3_Blink, it lights up the LED on the Arduino near pin 13, and it will also set whatever is attached to pin 13 (an LED) on a breadboard to HIGH (a.k.a. on).
Before we start to build our circuit, let’s take a look at the schematic for it. Doing so helps us visualize the electronic relationships in the circuit.
Our schematics from now on will include a symbol for the Arduino. Here is a schematic for the Arduino, with all of the digital, analog and power and ground pins labelled with their numbers or function, placed next to a drawing of the Arduino Uno for comparison. Don’t worry about memorizing the pin numbers and functionality now, we will explain more about the pins and their uses later on.
The schematic for the Arduino looks much more complicated than the other schematics we have seen previously. Its complexity reflects the number of connections possible with the Arduino hardware. Rather than try to cram this detailed Arduino schematic into the schematic of every circuit we build, we will use a simplified version: a rectangle that represents the Arduino, with labels only for the components we’re using in that circuit. Let’s see a full schematic of the circuit we’re going to build with the Arduino.
The schematic for our circuit
For the sake of clarity, when we include the Arduino in our schematics, we are only going to label the pins that are attached to the circuit we are building. For example, below is the schematic for the circuit we are about to build. Only pin 13, 5 Volts and ground are shown, as well as the LED and resistor.
Now that we’ve looked at the schematic, let’s see how we are going to build the circuit.