Turning an LED on

Within this tutorial we are going to make an LED turn on using Scratch and a Raspberry Pi.

Equipment You Will Need

  • 1 x red LED
  • 2 x male to female jumper wires
  • 1 x breadboard
  • 1 x 330 ohm resistor
  • Raspberry Pi
  • keyboard
  • Mouse
  • SD Card with Raspbian installed
  • HDMI cable
  • Compatible Screen
  • Power Supply

The Circuit

Lets build the circuit. Make sure you have your LED the right way round. The positive leg is the longer leg on the LED, this is represented by the bent leg in the diagram below:

LED Circuit

Code

The first thing we need to do is load scratch. To do this go to menu -> programming -> scratch.

  1. Once Scratch has opened click on the Control menu

  2. Drag a When green flag clicked block to the coding area.

  3. Next we need a Broadcast block. Connect it to the When green flag clicked block.

  4. Now click on the little black arrow and click the next/edit button. You should get a text box like this Text Box. In the textbox type gpioserveron and click OK.

  5. Drag another Broadcast block into the coding area and attach it to the GPIO Server On block. Click on the black arrow and click on new/edit. This time type config18out and click OK.

  6. We need another Broadcast block this time attach it to config 18 out block. Again click on the black arrow and edit/new. This time type gpio18on.

Your code should look like this Code

What The Code Does

  • When Green flag clicked This tells Scratch to run the code when the green flag is clicked.

  • GPIO server on This tells Scratch to interact with the GPIO pins on the pi.

  • Configure pin 18 This configures pin 18 on the raspberry pi as an output.

  • GPIO 18 on This tells the raspberry pi to turn GPIO pin 18 on, which is where your LED is attached.

Running The Code

Now that we have finished the code to run it click the green flag. You should now see the LED turn on, if you don’t go back and see where you went wrong.

Keep Having FUN while LEARNING!