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Exercise 2.1 - Lights and Buttons

e) Hardware button toggles the LED

This is the console. All output created with writeLog() is shown here.

Press the RGB LED button (hardware) to make the LED blue. Press it again to turn it off.

script.js

This is the JavaScript code behind the above application.

/* global writeLog, getInput, tf */
writeLog("Solution for exercise 2.1 e) Hardware button toggles the LED");
// Create a global variable to store the found devices
var devices;
var led;
var button;
// We'll use this variable to remember the LED state
var ledIsOn;
// Initialite connected devices
tf.initDevices(initDone);
// Call this when all connections are established
function initDone(connectedDevices) {
if (connectedDevices.length === 0) {
 writeLog("Oops, didn't find any devices! Make sure they are connected and refresh this page!");
 }
// Store the devices on the global variable
 devices = connectedDevices;
// Get the LED light
 led = devices.getDeviceByIdentifier(271);
// Get the LED button
 button = devices.getDeviceByIdentifier(282);
// Turn both LEDs off initially
 led.off();
 // Remember the LED's state
 ledIsOn = false;
button.off();
// Get notified when the button is pressedn
 button.registerListener(buttonPressed);
}
function buttonPressed(buttonEvent) {
 var buttonState = buttonEvent.getValue("button_state");
// When the state is RELEASED, the button must have been pressed before
 if (buttonState === "RELEASED") {
 if (ledIsOn) {
 led.off();
 ledIsOn = false;
 writeLog("Turned LED off.");
 }
 else {
 led.setColor(0, 0, 255);
 ledIsOn = true;
 writeLog("Turned LED on.")
 }
 }
}