Mark Baldridge is just out of high school, and wanted to tackle a project in a medium he knows and loves: pinball! He hand-built a pinball machine based on the online comedy duo Rhett&Link and controls all the electronics with a Raspberry Pi.
Being familiar with Python and Linux, Mark thought the Raspberry Pi to be a logical choice as a controller, but realized there were some limitations. The Pi only has a limited number of I/O pins, whereas his pinball machine would have many more switches, solenoids, and LEDs that would have to be individually controlled.
To overcome this hurdle, Mark used I2C, a master/slave buss interface for microcontrollers and peripherals. This interface was used with the MCP23017 microchip. This configuration makes it possible to increase the number of addressable GPIO pins on the Pi from 16 to 112!
The increased power needed by such components as the solenoids was handled by several transistors. The final product is quite impressive, with bumpers, flippers, lights, and a vertical-mounted LCD display. This young maker has created a formidable pinball machine.
[via Tech Fruits]