USB Control

The power of a personal computer can be leveraged to create pinball machine software with simple or complex rulesets, video sequences, and audio effects. The PC's audio output can be connected directly to a pinball machine, but interfacing to the machine's switch and driver circuits and to display elements such as a dot matrix display requires an interface card such as a P-ROC.

1 Hardware Implementation

The P-ROC has a type B USB connector allowing it to connect directly to a PC using a standard USB cable. The USB signalling protocol is handled by an FTDI FT245RL chip on the P-ROC. This chip buffers incoming data destined for the FPGA and outgoing data being sent back to the PC. For more information about the FT245RL chip, refer to its datasheet.

2 USB Drivers

FTDI provides a free, closed-source driver for the FT245RL chip called D2XX. P-ROCs have been verified to work successfully with Windows based systems using D2XX. Attempts to communicate with a P-ROC in Mac OS using D2XX have been unsuccessful due to an apparent bug in the Mac OS D2XX implementation.

A free, open-source driver called libFTDI is also available. P-ROCs have been verified to work successfully in Linux and Mac based systems using libFTDi.

3 USB Bandwidth

The P-ROC can send/receive approximately 1 MB of data each second, which is more than enough to exchange any information needed to control a pinball machine, including DMD animation information at frame rates exceeding 60 fps.