Add a small LED interface and demo app.

dart/examples/led/led.dart

Index: dart/examples/led/led.dart
diff --git a/dart/examples/led/led.dart b/dart/examples/led/led.dart
new file mode 100644
index 0000000000000000000000000000000000000000..c14ed149b1c51b3d9012d2b792ef8b950ccff312
--- /dev/null
+++ b/dart/examples/led/led.dart
@@ -0,0 +1,31 @@
+// Copyright (c) 2016, the Dartino project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE.md file.
+
+import "dart:dartino";
+import "dart:async";
+import "package:lk/leds.dart";
+
+int count = 0;

[ricow1, 2016/02/09 09:06:08]

remove unused variable

[herhut, 2016/02/09 10:10:15]

Thanks!

+
+makeCallback(LED) {
+  bool value = false;
+  return (Timer timer) {
+    LED.setState(value);
+    value = ! value;
+  };
+}
+
+void main() {
+  // Reset all LEDs for good measure.
+  LED0.setState(false);
+  LED1.setState(false);
+  LED2.setState(false);
+  LED3.setState(false);
+
+  // Add some blinking action.
+  new Timer.periodic(const Duration(milliseconds: 50), makeCallback(LED0));

[Søren Gjesse, 2016/02/09 09:16:01]

If you add toggle to LED (and make state both a getter and setter), then each of
these lines could be:

new Timer.periodic(const Duration(milliseconds: 100), () => LED1.toggle());

[herhut, 2016/02/09 10:10:15]

Done.

+  new Timer.periodic(const Duration(milliseconds: 100), makeCallback(LED1));
+  new Timer.periodic(const Duration(milliseconds: 75), makeCallback(LED2));
+  new Timer.periodic(const Duration(milliseconds: 333), makeCallback(LED3));
+}

[lukechurch, 2016/02/09 09:20:01]

Consider adding an explanatory comment as to why the program doesn't immediately
exit here.

[herhut, 2016/02/09 10:10:15]

Done.