This is a quick hack for enabling the use of either wireless Bluetooth and/or wired USB gamepads and mice on retro 8-bit and 16-bit computers such as Commodore Amiga and C64.
It works by reading events from HID input devices and emulating the pins of DB9 joysticks and a mouse on a Raspberry Pi and sending the signals via a 16-channel I/O board using the MCP23017 expander connected via I2C.
I've tested this code with two PS3 Sixaxis controllers (both in wired USB and Bluetooth mode) and an XBOX 360 wireless controller (via the USB adapter). The mouse support has been tested with a Microsoft 3600 Bluetooth Mouse and a wired SteelSeries Sensei Raw.
Any USB and Bluetooth HID devices are supported, as long as they present a Linux event device that can be accessed as
A more in-depth article on the project including some photos of the hardware can be found here:
For Raspbian users, install packages
libi2c-dev to compile with the provided Makefile using GNU Make.
Usage: ./joyemu [-vqh] [-i bus] [-a addr] [-d (j1|j2|m):evdev] [-m port] [-j port] [-e type] -v add verbosity -q add quietness -i n set I2C bus number for I/O expander (default: 1) -a 0xnn set I2C address for I/O expander as a hexadecimal byte (default: 0x20) -d j1:n set event device number for joystick 1 -d j2:n set event device number for joystick 2 -d m:n set event device number for mouse -m n set mouse port: 1 (default) or 2 -j n set first joystick port: 1 or 2 (default) -e n set mouse emulation type: 0=Amiga (default), 1=Atari ST -h display this help
Note that if you log very verbosely to the console, the response to the inputs - especially that of the mouse - may begin to lag noticeably. Only use the more verbose debugging levels for actual debugging.
I'm developing this on a Raspberry Pi Zero W and an IO Pi Zero expander board from AB Electronics. The reason I'm using a separate I/O expander is that the Atari-style DB9 joystick ports are active-low, so the pins on the computer end have pull-up resistors to +5V. On a Commodore C64 the pull-ups are internal to the CIA chips, whereas on an Amiga A500 or A1200 use external 4.7Ω resistors. The GPIO pins on the Raspberry Pi are not safe for +5V so they cannot be used unless external level conversion is used.
Any other I/O board (or built-in GPIOs with level conversion) would probably work equally well, as long as it sends 0V..+5V and tolerates the +5V pull-ups. Of course, you'd also have to rewrite
io.h accordingly to support the hardware.
GPIO lines on the MCP23017 are connected to DB9 pins as follows:
Bits 6 and 7 on GPIOA and GPIOB are unused.
I've added a 2x8 pin header on the I/O board and built a cable that connects the corresponding GPIO pins to two female DB9 connectors. Remember to also connect the ground plane on the I/O board with the ground pin on the DB9 connectors (pin 8).
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