** SUMMARY ** This repository contains code that interfaces a BeagleBone Black (BBB) SBC with a pair of Super Nintendo Entertainment System (SNES) gamepads. It uses a Programmable Realtime Unit (PRU) of the BBB with userspace I/O (UIO) to bitbang the gamepad serial interface.

** AUTHOR ** Andrew Henderson (hendersa@icculus.org): https://icculus.org/~hendersa

** DESCRIPTION ** Four BBB GPIOs are used:

OUTPUTS Gamepad Clock: P9.11 (GPIO0[30]) Gamepad Latch: P9.13 (GPIO0[31])

INPUTS Gamepad 1 Data: P9.17 (GPIO0[03]) Gamepad 2 Data: P9.21 (GPIO0[05])

The details of the protocol are described here: https://gamefaqs.gamespot.com/snes/916396-super-nintendo/faqs/5395

The key files in this repository are:

prussdrv/* : The Texas Instruments prussdrv driver library pru.c : Convenience wrapper functions around the prussdrv interface prugamepad.c : Starts execution of PRU firmware and parses gamepad data gamepad.p : PRU firmware code (PRU assembly) setup.sh : Convenience shell script to set directions on the GPIO pins wiring.png : Suggested wiring diagram for the interface circuit

** BUILDING ** To build the gamepad.p file, you'll need the PASM tool:

$ git clone https://github.com/beagleboard/am335x_pru_package $ cd am335x_pru_package/pru_sw/utils/pasm_source $ ./linuxbuild $ sudo cp ../pasm /usr/local/bin

Once PASM is installed, you can build the software (on your BBB) via make:

$ make

Then, set the pin directions using the setup script:

$ sudo ./setup.sh

Finally, run the test program:

$ sudo ./prugamepad