Writing Arduino code

Two ways to write codeCopy Anchor Link

The Code panel next to the circuit has a mode for each way of programming the board. A question can limit which one you may use.

The editor has syntax colouring and autosaves.

Your first sketchCopy Anchor Link

The starter sketch blinks the built-in LED on pin 13 and prints "on" and "off" to the serial monitor. This is the idea:

void setup() {
  pinMode(13, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  digitalWrite(13, HIGH);
  Serial.println("on");
  delay(500);
  digitalWrite(13, LOW);
  Serial.println("off");
  delay(500);
}

Wire an LED (with a resistor) from pin 13 to ground, press Upload, and it blinks.

FilesCopy Anchor Link

• Most programs are a single file (sketch.ino or main.c). A program can have up to 8 files, and the whole program can be at most 64 KB.
• File names use letters, digits, _ and -, then a short extension, for example helpers.h.
• Sketches can use .ino, .cpp, .c, .h and .S. AVR C can use .c, .h and .S.
• If you have several .ino tabs, they are joined together the way the Arduino IDE does it. Function prototypes are made for you, so you can call a function that is defined below loop().

Libraries you can includeCopy Anchor Link

These are built in. You can #include them without installing anything.

Language notesCopy Anchor Link

• The board uses the standard Arduino AVR core. C++ exceptions are not available.
• Errors point to your own file and line, for example sketch.ino:3.