Back to: Arcade1Up Costco Super Pac-Man mod
Back to: 11. Connect the Marquee Light
Now that all the main parts are working, as a final step we want the power to the Screen and Marquee light to be controlled by the Raspberry Pi. When the Pi boots up, the screen should be powered up, and when the Pi goes to Stand-By or is turned off, the power to the screen should be cut off as well.
To achieve this, you need a Relay Switch that can be controlled via the Raspberry Pi. Through this Relay, the household power to the screen and marquee light can then be managed.
I used 2 regular household receptacles to build the power supply for the Arcade. In one of them, I broke out the brass tab on the side because that connection is to be managed by the Relay Switch. That way, one outlet will always be powered and this is where the Raspberry Pi will be powered from. The other 3 outlets can be turned on or off through the Relay Switch that the Pi controls.
The receptacles and Relay Switch are all placed and secured in a Double Gang Device Box that you can find at your local hardware store. I used double sided tape to stick the Relay Switch to the back of the box. I also removed the metal ground strips before placing everything in the box.
Before connecting any household voltage to your setup, make sure to test everything first with a multi meter. You don’t want to run the risk of frying all your stuff because of a wrong connection.
Finally, the device box and Pi are secured to the bottom of the Arcade with some double sided tape.
In order for the Pi to control the Relay Switch, download and install this custom program on your Pi. Instructions are on that page. Initially I had the SainSmart Relay hooked up to a 3.3V pin on the Pi, but the relay did not always reliably work. It worked fine on the 5V pin.
One of the things I noticed was that after I had the screen power controlled through the Pi, the screen resolution seemed low and blurry. It turns out that the Pi had trouble determining the resolution before the screen was turned on, but it worked fine if the screen was already on before powering up the Pi.
In order to remedy this, you need to tell your Pi what the screen resolution is, so that it does not need to try and figure this out by itself. In /boot/config.txt add the following lines:
hdmi_group=2
hdmi_mode=35
HDMI group 1 is for normally used for TVs (CEA) while group 2 is mainly used for monitors (DMT). In group 2, HDMI mode 35 corresponds to a resolution of 1280×1024, ratio 5:4, 60hz frequency.
Before putting the back panel back in place, create a small notch at the bottom of the panel for the power cord to fit through.
