Learn Arduino with Olympia Circuits
Learn Arduino
  • Home
    • Get Started
    • How to Use This Site
  • Electronics
    • The Basics
    • Electricity Flows like Water
    • Electronic Components
    • The Arno Board
  • Programming
    • The Basics
    • setup and loop Blocks
    • Variables and Arrays
    • Connecting with the Pins
    • Flow Control >
      • if Statement
      • Loops
      • Delays
    • Functions
    • Serial Communication
    • USB
    • Some Thoughts
  • Projects
    • Projects 1 >
      • 1.01: Blink
      • 1.02 Blink x2
      • 1.03 Blink Faster
      • 1.04 LED Chase!
      • 1.05 Wait To Blink
      • 1.06 Blink a Little Faster Now
      • 1.07 LED Fade
      • 1.08 RGB Blink
      • 1.09 Change RGB Color with SW1
      • 1.10 Fade RGB Colors
      • 1.11 Reaction Time Game
    • Projects 2 >
      • 2.01 Hello World
      • 2.02 Talk Back
      • 2.03 ASCII Values
      • 2.04 Ski Game
      • 2.05 Demonstration of the String Object
    • Projects 3 >
      • 3.01 Read the Potentiometer
      • 3.02 ASCIIbet Soup
      • 3.03 Potentiometer sets LED Brightness
      • 3.04 Potentiometer Sets Blink Rate
      • 3.05 LED Chase, Part II
    • Projects 4 >
      • 4.01 Bringing the Piezo to Life
      • 4.02 Controlling the Piezo with a Function
      • 4.03 Piezo C Major
      • 4.04 Piezo Greensleaves
      • 4.05 Piezo Metronome
      • 4.06 Piezo as an Input
      • 4.07 Piezo as an Input 2
      • 4.08 Metronome II
      • 4.09 Piezo Playback
      • 4.10 Piezo Fireworks
      • 4.11 Piezo Mosquito
    • Projects 5 >
      • 5.01 The Phototransistor
      • 5.02 Light and Sound
      • 5.03 Light and Sound II
    • Projects 6 >
      • 6.01 EEPROM
      • 6.02 I2C Address Scan
      • 6.03 Read the I2C Temperature Sensor
      • 6.04 High Temperature Alarm
    • Projects 7 >
      • 7.01 Arno Phone Home
      • 7.02 Keyboard Alphabet
      • 7.03 Move Mouse
      • 7.04 Draw Squares
    • Special Projects >
      • Bike Light Demo
  • References
    • Arno Pin Key
    • Arno Schematic
    • Project Index

programming: The basics

A program, or sketch, is a set of instructions that the Arno will execute.   Computers take the world very literally.  They need to be told exactly what to do in a language that they understand.  Luckily, programming in Arduino is fairly simple.  But you need to know the rules and follow them exactly.  Here are a few rules to remember:

  1. All sketches need to have at least two parts: the setup() and loop() blocks.  We’ll explain them below.
  2. Most lines end with a semicolon ;  We normally press the Enter key after the semicolon but Arduino knows that the line ends when it sees a semicolon.
  3. Arduino is case-sensitive.  So the word ‘setup’ is not the same as ‘Setup’.  This is true of both Arduino commands and variables that you create.
  4. When Arduino sees the two character ‘//’ it ignores everything until the end of the line (when the Enter key is pressed).  This allows us to add human-readable comments to our sketches.  Arduino doesn’t need to know what our comments mean.  They’re used to describe to other people what the program does and to remind ourselves what we were thinking when we wrote it.  You can also include a block of several lines of comments in a sketch by starting the block with /* and ending it with */.


To help you follow along, we underline the names of variables and bold programming keywords and other symbols when we’re discussing Arduino code.

Next: setup and loop blocks

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