Blink an LED

The GPIO "hello world": flash an LED on and off.

Wiring

GPIO17 ──▶│── 330Ω ──┐
         LED         │
                    GND

LED anode → GPIO17, cathode → 330 Ω → GND.

Code

namespace Demo

import Amalgame.Hardware
import Amalgame.DateTime

public class Program {
    public static void Main(string[] args) {
        let led: int = 17

        if (!Gpio.PinMode(led, PinMode.Output)) {
            Console.WriteLine("could not open GPIO17 — check permissions")
            return
        }

        var i: int = 0
        while (i < 20) {
            Gpio.Toggle(led)               // flip the output
            DateTime.SleepMillis(500)      // ...every half second
            i = i + 1
        }

        Gpio.Close()                       // release the line
    }
}

Run

amc package add datetime     # once — for DateTime.SleepMillis
amc build main.am -o blink
./blink

What's happening

• Gpio.PinMode(17, PinMode.Output) requests GPIO17 as an output. It returns false (rather than crashing) if the line is busy or you lack permission — always check it.
• Gpio.Toggle(17) flips the current level. You could be explicit with Gpio.DigitalWrite(17, Level.High) / Level.Low instead.
• Gpio.Close() releases every line the program requested. The kernel would reclaim them on exit anyway, but closing is tidy.
• DateTime.SleepMillis(500) pauses for half a second. It comes from the amalgame-datetime package (DateTime.SleepSeconds(s) and Duration.Sleep() are there too) — pure Amalgame, no inline C in your program.

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