Steveshoyer: Using USB with a P-ROC

2016-02-08T05:27:19Z

Using USB with a P-ROC

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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.

=== 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 [http://www.ftdichip.com/ FTDI] [http://www.ftdichip.com/Products/FT245R.htm 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 [http://www.ftdichip.com/Documents/DataSheets/DS_FT245R_V206.pdf datasheet].

=== USB Drivers ===

[http://www.ftdichip.com/ FTDI] provides a free, closed-source driver for the FT245RL chip called [http://www.ftdichip.com/Drivers/D2XX.htm 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 [http://www.intra2net.com/en/developer/libftdi/ libFTDI] is also available. P-ROCs have been verified to work successfully in Linux and Mac based systems using libFTDi.

=== 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.

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Steveshoyer: Using USB with a P-ROC