American Girl Pinball Teardown 3: Backbox communication

Dismantling "The Flip Side", a 1:5 scale pinball machine created by American Girl (the doll company). This is the 3rd video in a series where I disassemble and reverse engineer this cool little machine. In this video we figure out how the playfield microcontroller communicates score digits to the backbox. We once again see that the original software doesn't make full use of the machine's display capabilities.
00:00 : Objective
00:44 : SPI Explanation
03:22 : Powering the boards
11:14 : Probing power, optos, and SPI
19:45 : Connecting Arduino
29:20 : Reading SPI data
40:06 : Decoding SPI score data
44:02 : Controlling score display
See the rest of the teardown series and my review of the machine before I tore it apart: • American Girl Pinball