Approach this page the way you would approach the first few lines of a foreign language you want to learn. Try to pick out words that make sense, without worrying about the overall structure, correct syntax, or proper grammar. As time passes and you have learned new things, come back to this page and see whether you can understand a bit more of it.

The Skeleton of an Arduino Program

void setup() {

}

void loop() {

}

This program does absolutely nothing.

Extra Elements of a SpinWheel Program

// Include extra resources and commands
// specific to the SpinWheel.
#include "SpinWearables.h"
using namespace SpinWearables;

void setup() {
  // Instruct the specific SpinWheel hardware
  // to be ready to receive instructions.
  SpinWheel.begin();
}

void loop() {

}

Make it light up:

#include "SpinWearables.h"
using namespace SpinWearables;

void setup() {
  SpinWheel.begin();
}

void loop() {
  // Set the large LED number 0 to
  // have red=255, green=0, and blue=0 color.
  SpinWheel.setLargeLED(0, 255, 0, 0);
  // Update the currently shining LEDs
  // based on the instructions provided up to here.
  SpinWheel.drawFrame();
}

Creating changing patterns

To begin writing more complex code, we need to introduce the idea of variables. Variables allow us to store information in the program and change that information as needed.

To define a new variable we can add the following line to the loop block:

int which_LED = 1;

Additional Programming Notes

• Only one “command” per line. This makes the code more readable.
• Command are followed by a semicolon ;.
• Commands tend to be some name followed by parentheses ().
• Inside these parentheses we put some extra information: this information can control how a command performs.

Variables

Before processing data, we have to tell the computer to store it in its memory. This is done using variables.

We will only discuss two types of variables: integers and decimals. Other types do exist, but we won’t cover them here.

To define a new integer variable you need the following line in your code:

int my_special_integer = 6;

If we want to work with decimals, we use the variable type float instead of int. The name comes from the early history of computers and is unimportant for our purposes (how the decimal point can “float” between the digits).

float pi = 3.1415;

Functions

In computer programming, functions are commands that take a few variables and do something useful with them. Functions are reusable pieces of code.

Here is some code that uses an example function called max that takes two numbers as input and returns the larger number. The input values are also called the arguments of the function.

int number_a = 5;
int number_b = 7;
int resulting_number = max(number_a, number_b);

int number_a = 5;
int number_b = 7;
int resulting_number = max(number_a, number_b);

The value stored in resulting_number in this case would be 7.

Creating your own functions

float x = 3.5;
float y = 2.5;
float resulting_number = avg(x, y);

In this code example, resulting_number will have the value of 3.0.

To define this new function, we need to write down its name, together with the type of data it will be producing, followed by a set of computational instructions:

float avg(float first_argument, float second_argument) {
  return 0.5*(first_argument+second_argument);
}

Functions that do not return values

a = calculation1();
delay(1000);
b = calculation2();

Comments

// I am writing this comment to remind me
// that the next line stores the number 5
// in the variable named my_test_variable.
int my_test_variable = 5;