arduino.c3l

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Blink Walkthrough ​

The blink example is the smallest useful arduino.c3l program. It configures the built-in LED pin as an output and toggles it once per second.

Open the example ​

sh
cd examples/blink

Important files:

text
examples/blink/
├─ project.json
├─ scripts/flash.sh
└─ src/blink.c3

Source code ​

c3
module blink;

import arduino::gpio;
import arduino::time;

fn void main() @export("start") {
    gpio::pin_mode(D13, OUTPUT);

    while (true) {
        gpio::digital_write(D13, HIGH);
        time::delay_ms(1000);
        gpio::digital_write(D13, LOW);
        time::delay_ms(1000);
    }
}

Explanation ​

Module declaration ​

c3
module blink;

Every C3 source file belongs to a module. The example uses its own blink module.

Imports ​

c3
import arduino::gpio;
import arduino::time;

arduino::gpio provides pin_mode, digital_write, pin aliases like D13, and constants like OUTPUT, HIGH, and LOW.

arduino::time provides blocking delay helpers such as delay_ms.

Entry point ​

c3
fn void main() @export("start") {

The AVR target is configured without the standard library entry point. Exporting main as start gives the minimal runtime a known symbol to call.

Configure the LED pin ​

c3
gpio::pin_mode(D13, OUTPUT);

On Arduino Uno style boards, D13 is connected to the built-in LED.

Toggle forever ​

c3
while (true) {
    gpio::digital_write(D13, HIGH);
    time::delay_ms(1000);
    gpio::digital_write(D13, LOW);
    time::delay_ms(1000);
}

The loop turns the LED on, waits one second, turns it off, and waits another second.

Build and flash ​

sh
c3c build
./scripts/flash.sh

If flashing fails, check the serial port in scripts/flash.sh and see Build & Flash.