test-led-scratch.md

Testing a connected LED in Scratch

1. With your LED circuit complete, you are now ready to use Scratch to switch the LED on. Launch the program Scratch by clicking on Menu followed by Programming and selecting Scratch.

Our version of Scratch on Raspbian is extra special. It allows you to access and control the GPIO pins.

![](images/Scratch-interface.png "The Scratch Interface")

1. Click on Control in the top left display. Drag the block onto the scripts area.

2. Drag a broadcast block to your scripts area and attach it to the block. Click on the drop down menu on the broadcast block and select new.

   In the message name box type gpioserveron This instruction will tell the Scratch to activate its GPIO functions.

3. Drag another broadcast block to your scripts area and attach it to the bottom. Click on the drop down menu on the broadcast block and select new.

   In the message name box type config17output This instruction will tell the Raspberry Pi to set GPIO pin 17 as an output.

   

4. Drag another broadcast block to your scripts area and attach it to the bottom of first broadcast block. Click on the drop down menu on the broadcast block and select new.

   In the message name box type gpio17on This instruction will tell the Raspberry Pi to set GPIO pin 17 HIGH.

5. Drag a wait 1 secs block onto the scripts area and connect it to the previous broadcast block.

6. Drag one last broadcast block onto your scripts area and connect it to the wait 1 secs block. Click on the drop down menu on the broadcast block and select new.

   In the message name box type gpio17off This will switch off the LED.

7. Save your work so far by clicking on File and Save As. Name your file Test LED and click OK.

8. Test your program by clicking on the icon. You should see the LED come on for 1 second and then turn off.

   

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