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Blink ​

The blinking LED example is the traditional Hello World program for microcontrollers. The program turns an LED on and off at a regular interval.

Circuit ​

For this example you require:

  1. A microcontroller
  2. An LED (optional)
  3. 220 ohm resistor (optional)

The LED and 220 ohm resistor are optional, most microcontrollers come with a built-in LED that you can use for this example.

Program ​

Once you have built the circuit, you can write the blinking LED example for WARDuino. First you need to initialize the pin connecting the LED as an output pin.

ts
pinMode(led, PinMode.OUTPUT);
rust
pin_mode(led, PinMode::OUTPUT);

Then in an infinite loop, we want to turn the LED on. In the code we use a variable led that holds the correct pin number.

ts
digitalWrite(led, PinVoltage.HIGH);
rust
digital_write(led, PinVoltage::HIGH);

Here, the digitialWrite primitive makes the microcontroller supply 5 volts to the LED anode, turning the LED on. Next we want to turn the LED off, by bringing the pin back to 0 volts.

ts
digitalWrite(led, PinVoltage.LOW);
rust
digital_write(led, PinVoltage::LOW);

Without a delay between these commands, a person could never observe the change. So we can tell the board to do nothing for a number of milliseconds.

ts
delay(1000);
rust
delay(1000);

Here is the full code.

ts
// Blinking LED example
import {pinMode, PinMode, PinVoltage,
        digitalWrite, delay} from "as-warduino/assembly";

export function main(): void {
    const led: u32 = 26;
    const pause: u32 = 1000;

    pinMode(led, PinMode.OUTPUT);

    while (true) {
        digitalWrite(led, PinVoltage.HIGH);
        delay(pause);
        digitalWrite(led, PinVoltage.LOW);
        delay(pause);
    }
}
rust
// Blinking LED example
use warduino::{delay, digital_write, pin_mode, PinMode, PinVoltage};

#[no_mangle]
pub fn main() {
    let led: u32 = 26;
    let pause: u32 = 1000;

    pin_mode(led, PinMode::OUTPUT);

    loop {
        digital_write(led, PinVoltage::HIGH);
        delay(pause);
        digital_write(led, PinVoltage::LOW);
        delay(pause);
    }
}

Learn More ​

Also, check out the Blink Without Delay example to learn how to create a delay while doing other things.