Homebrew Pinball #3, Part 69

Cross posted from the original Pinside thread, this is one of many posts regarding my third homebrew pinball machine, creatively nicknamed 'P3'

I'd been getting tired of using the projector for everything, and with the lights taking away half of its use, I figured it was a good time to get to work on the other part of that: the cards themselves. I'd realized early on that having all the cards just printed on the playfield, unchangeable, would have a possibility for people finding certain cards to go for every time which would make the game less fun, and having the projector able to deal a random set of cards onto the playfield solidified that worry. And then I found some cheap LCD displays on ali express while searching for the main screen I installed before
Turns out they were slightly narrower than the spacing on the drop targets:
Thanks to the provided example code it wasn't very hard to get one to display a card using a raspberry pi
But could you drive more than one easily? I made a little board that had a shift register on it to control the CS line of the display, so that I could theoretically wire up to 8 displays to it

So far so good! Now, could I fit those displays in front of the targets? I did some measurements of the 3 bank in the middle and printed a bracket

And they fit! barely.
I programmed a simple tcp server to control them, and hooked the 3 displays into the game
Alright, proof of concept complete. Time to go way too far with this.

I'll need to custom make a bracket for every bank in the game, since they're all different manufacturers+sizes

And since I'm already getting into this, why not throw some other single displays around the playfield?

Now, can I actually drive them all? No. I lose signal around the fourth board. A lot of learning about signal integrity and I've got another version of my board with some termination resistors and a buffer chip to redrive the signal between each board
And with that, I can barely get all my displays to work

So I cross my fingers and cut a lot of big holes in my playfield. The amount of missing wood at this point is starting to concern me a bit, but it seems to hold up okay when the side rails are attached.
Wiring them up is also fun. So many ribbon cables! Almost looks like a Spooky game...
And once I finally got the whole playfield reassembed...

Posted Tuesday, November 16, 2021
at 11:29 AM

Tags: Blog Post, Pinball, Project, P3,

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