Red, Yellow and Green LEDs
Overview
In this tutorial you will learn how to create a simple LED sequencer circuit, access Cloud9 (the BeagleBone's coding interface), load and run a script. When you run the script the LEDs will blink. The code introduces the random function for the LED sequence and how to control multiple digital outputs.Note: This tutorial uses a BeagleBone set up specifically for our BeagleBone Black Tinkerer Workshop. The BeagleBone Black you will use in the Tinkerer Workshop will be set up with a Display and a Keyboard with a trackball mouse, and the JavaScript Files will be saved to the board. The BeagleBone will be running Angstrom, which come pre-loaded when you get the board. If you are not in a Tinkerer Workshop and want to do these projects, you can find a guide on how to attach a keyboard with a trackball mouse and a display here. You will also need to add the JavaScript files, which can be found here, to the following directory on the BeagleBone Black: /var/lib/cloud9/workshop
Parts List
- 1x BeagleBone Black Board
- 1x Medium Breadboard
- 1x Jumper Wire Pack for Breadboards
- 2x LEDs (Red, Green) (Available in the Prototyping Parts Kit)
- 1x LED (Yellow) can use RGY multicolor LED in Prototyping Parts Kit
- 3x 330 Ohm Resistor (Also available in the Prototyping Parts Kit)
Wiring Diagram
Step 1
Wire the components as shown. The LED is polarized (only works one-way)Note: The resistor is required to limit the current to the LED.
Step 2
Plug the DC power jack into the BeagleBone Black to power the device.Step 3
Once the system is ready, click on BEAGLEBONE-workshop icon to open the Chromium browser and then start the Cloud9 IDE BeagleBone.local:3000 (192.168.7.2:3000)Step 4
In the Cloud9 workshop folder click on the file Project2.js to open the BoneScript program that will control the LED and make it blink.The code should look like this:
var b = require('bonescript'); // Read library
var ledPin1 = "P9_14"; // Select pins
var ledPin2 = "P9_16";
var ledPin3 = "P8_19";
b.pinMode(ledPin1, b.OUTPUT); // Enable pins and set to output
b.pinMode(ledPin2, b.OUTPUT);
b.pinMode(ledPin3, b.OUTPUT);
setInterval(random, 300); // Call function 'random' every 300ms
function random(){ // Define function 'random'
b.digitalWrite(ledPin1, Math.round(Math.random()));
b.digitalWrite(ledPin2, Math.round(Math.random()));
b.digitalWrite(ledPin3, Math.round(Math.random()));
}
Step 5
Now press Run at the top of the Cloud9 interface. If this says "Debug", select "Run" from the drop down under this button.
