In order to get the sequenced firing working to test the 5 bank, I had to get some more control going on. Previously when testing the flippers I was just editing the driver board firmware manually to configure coils. I made a custom MPU board with hookup for up to 8 external driver boards for solenoids, lights, displays, etc. It's powered via a raspberry pi for simplicity, and also has support for an 8x16 switch matrix. Here's my first test setup, with the two boards just screwed to a spare piece of foam core.
The driver board can have each solenoid configured with a default pulse time, a maximum on time, and PWM duty cycle. The switch matrix and board I/O are handled via a small Java app for now, which can be connected to via a socket to send commands. The game code will eventually send those commands, but for now it makes for easy testing to just connect directly to the socket via PuTTY and type them in. To fire the 5 bank, I just made a quick bash script to send six commands in a loop with some pauses in between.