Smoke Testing

At this point, there should be enough on the screen to test what has been done so far. Overall the test process is:

  • Wire up power to everything
  • Build a temporary data cable
  • Power up the panels and the BBB
  • Manually execute a game

 

Do not plug the USB cable into the BeagleBone Black if there is any possibility that the LED matrix panels do not power.

Powering the test

The BeagleBone Black can draw all it's power off the USB cable, which is a nice feature for small projects. However, the LED matrix panels need more current than this can supply, and always having the USB plugged in may not be convenient. So the power will be supplied via the power jack.

A problem can arise if the panels are unpowered and the USB cable is plugged in. The BeagleBone Black will come up and start sending something to the panels, which can cause damage to the electronics of the panels. I have done it accidentally, and the panels are still fine, but I recommend avoiding this at all costs.

Start by making sure all four panels have the wiring attached, and that the wiring is attached to the power bus from the last step.

Next plug the Male DC Power adapter into the BeagleBone Black.

Finally plug the power supply into the Female DC Power adapter. Don't plug it into the wall yet.

LED Data Cable

Before you begin this step, take the time to read this article about wiring LED matrix panels. Hopefully this is just plugging in some cables, but if things look 'wrong', that article can help you correct any issues.

 

Take a nice, long 16-conductor ribbon cable and plug it in to the LED Connector on the proto cape you built earlier. This should be attached with the red wire at the 'top' edge, that is towards the notch in the PCB. 

And this goes to the 'input' side of one of the panels. Any panel will do at the moment, but this will eventually be the bottom right panel.

For the other three panels, just hook the input of one panel to the output of the previous one. This will make a daisy chain going from the BBB, to the lower right panel, to the lower left, to the upper right, to the upper left. Since this is a test, don't worry about positioning them, just lay the chain out on your work table.

Attach the cape

Place the BBB on a firm surface, and make sure that there is nothing under it. Align the pins on the cape with the holes on the BBB, and press down. It will take a lot of force to get all the pins to settle in place.

Attach USB audio

The games depend on the USB audio card being installed, so attach it now. An earphone will be required to hear anything, but even without that, the games will be happy.

Apply power, and test!

Finally you get to plug the power supply into the wall. The lights on the BBB should start to flash as it boots up. Connect to the BBB with SSH, and change to the directory where you cloned the git repo. This is probably ~/LEDscape, so go there now.

To start one of the games, type:

bin/run-ledscape

After a short delay (about 10 seconds while the BBB injests the cape definition files), the LED matrices should light up, and you should see pieces of the "Bricks" game.

Autostarting...

Of course, a game should come up immediately upon booting, so that an SSH session isn't always required. To set this, do:

cp bin/ledscape.service /etc/systemd/system/

systemctl enable ledscape.service

systemctl status ledscape.service

 

This guide was first published on May 04, 2015. It was last updated on Sep 24, 2018. This page (Smoke Testing) was last updated on May 04, 2015.