Progress

Tonight I had some time work on the project so I grabbed a current version of retropie and used the Win32 Disk Imager to put it on the SD Card. The cart formatting process gave me a couple errors and when I loaded it into the pi it still had the old image on the card. After a lather, rinse repeat I purchased a new card and it worked first time. 

I used the USB connection from the power supply and the HDMI panel mounted cable connection to verify that the Pi was able to boot and transmit the video. I flipped the switch and it booted right up. Even the cooling fans were wired up right and started spinning. Most of the projects I work on professionally appear much simpler and I still feel weird that bringing it together actually worked first time. 

I also setup and tested the bluetooth dongle to JoyCon controller which worked great too. The instructions posted on retropie's website were accurate and helpful. It was really encouraging to see a large portion of the guts come together and work well. 

Next Steps

I'm still waiting on the small USB splitter to arrive to finish the cart, but in the meantime I can drill the holes and mount the spacers and guides for the cart connector. That does reveal one of my current big unknowns which is how to set up the cart guides so it has a clear path as you push the cart into the ammo can chassis. This will probably need a redesign of the the main entrance guide which is pretty flimsy right now.  It is really tempting to just finish it as is and spend more time on the next generation / project. 

• The next version of this project should have some sort of fan control. There are hooks in the raspberry pi OS where the fans can be controlled. I'd like to look into this and make it so the fans aren't on all the time.
• It would be cool to have one a push pop mechanism for loading and unloading the cartridges, like the push-up push-down  spring and latch system from the original NES. That click is really satisfying and makes things easy to identify if they are ready to go.