The Raspberry Pi GPIO Joystick Driver

The mk_arcade_joystick_rpi is fully integrated in the recalbox distribution : see http://www.recalbox.com

The branch hotkeybtn now support one more button per player in place of MCP23017 support. And also gpio customization for both players

The RaspberryPi is an amazing tool I discovered a month ago. The RetroPie project made me want to build my own Arcade Cabinet with simple arcade buttons and joysticks.

So i started to wire my joysticks and buttons to my raspberry pi, and I wrote the first half of this driver in order to wire my joysticks and buttons directly to the RPi GPIOs.

However, the Raspberry Pi Board B Rev 2 has a maximum of 21 usable GPIOs, not enough to wire all the 28 switches (2 joystick and 20 buttons) that a standard panel requires.

UPDATE 0.1.5 : Added GPIO customization

UPDATE 0.1.4 : Compatibily with rpi2

UPDATE 0.1.3 : Compatibily with 3.18.3 :

The driver installation now works with 3.18.3 kernel, distributed with the last firmware.

UPDATE 0.1.2 : Downgrade to 3.12.28+ :

As the module will not load with recent kernel and headers, we add the possibility of downgrading your firmware to a compatible version, until we find a fix.

UPDATE 0.1.1 : RPi B+ VERSION :

The new Raspberry Pi B+ Revision brought us 9 more GPIOs, so we are now able to connect 2 joysticks and 12 buttons directly to GPIOs. I updated the driver in order to support the 2 joysticks on GPIO configuration.

The joystick driver is based on the gamecon_gpio_rpi driver by marqs

It is written for 4 directions joysticks and 9 buttons per player.

It can read one joystick + 9 buttons wired on RPi GPIOs (two on RPi B+ revision)

It uses internal pull-ups of RPi, so all switches must be directly connected to its corresponding GPIO and to the ground.

Let's consider a 7 buttons cab panel with this button order :

 ↑   Ⓨ Ⓧ Ⓛ  
← →	 Ⓑ Ⓐ Ⓡ Ⓗ
 ↓  

With Ⓡ = Right trigger = TR and Ⓛ = Left trigger = TL
Ⓗ is the Hotkey.

Here is the rev B GPIO pinout summary :

If you have a Rev B+ RPi or RPi2:

Of course the ground can be common for all switches.

Download the installation script :

mkdir mkjoystick
cd mkjoystick
wget https://github.com/digitalLumberjack/mk_arcade_joystick_rpi/releases/download/v0.1.4/install.sh

Update your system :

sudo sh ./install.sh updatesystem
sudo reboot

Don't forget to reboot (or the next part won't work) and re-run the script without any arguments :

sudo sh ./install.sh

Now jump to Loading the driver

Update system :

sudo apt-get update
sudo apt-get upgrade
sudo rpi-update

1 - Install all you need :

sudo apt-get install -y --force-yes dkms cpp-4.7 gcc-4.7 git joystick

2 - Install last kernel headers :

sudo apt-get install raspberrypi-kernel-headers

3.a - Install driver from release (prefered):

wget https://github.com/digitalLumberjack/mk_arcade_joystick_rpi/releases/download/v0.1.4/mk-arcade-joystick-rpi-0.1.4.deb
sudo dpkg -i mk-arcade-joystick-rpi-0.1.4.deb

3.b - Or compile and install with dkms:

3.b.1 - Download the files:

git clone https://github.com/pinuct/mk_arcade_joystick_rpi

3.b.2 - Create a folder under "/usr/src/module-module-version/"

mkdir /usr/src/mk_arcade_joystick_rpi-0.1.5/

3.b.3 - Copy the files into the folder:

cd mk_arcade_joystick_rpi/
cp -a * /usr/src/mk_arcade_joystick_rpi-0.1.5/

3.b.4 - Compile and install the module:

dkms build -m mk_arcade_joystick_rpi -v 0.1.5
dkms install -m mk_arcade_joystick_rpi -v 0.1.5

The driver is loaded with the modprobe command and take one parameter nammed "map" representing connected joysticks. When you will have to load the driver you must pass a list of parameters that represent the list of connected Joysticks. The first parameter will be the joystick mapped to /dev/input/js0, the second to js1 etc..

If you have connected a joystick on RPi GPIOs (joystick 1 on the pinout image) you must pass "map=1" as a parameter. If you are on B+ revision and you connected 2 joysticks you must pass map="1,2" as a parameter.

If you have one joystick connected on your RPi B or B+ version you will have to run the following command :

sudo modprobe mk_arcade_joystick_rpi map=1

If you have two joysticks connected on your RPi B+ version you will have to run the following command :

sudo modprobe mk_arcade_joystick_rpi map=1,2

If you have a TFT screen connected on your RPi B+ you can't use all the gpios. You can run the following command for using only the gpios not used by the tft screen (Be careful, not all tft screen use the same pins. GPIOs used with this map: 21,13,26,19,5,6,22,4,20,17,27,16,12):

sudo modprobe mk_arcade_joystick_rpi map=3

If you don't want to use all pins or wants a custom gpio map use:

sudo modprobe mk_arcade_joystick_rpi map=4 gpio=pin1,pin2,pin3,.....,pin12

Where pinx is the number of the gpio you want. There are 12 posible gpio with button order: Y-,Y+,X-,X+,start,select,a,b,tr,y,x,tl,hk. Use -1 for unused pins. For example gpio=21,13,26,19,-1,-1,22,24,-1,-1,-1,-1,-1 uses gpios 21,13,26,19 for axis and gpios 22 and 24 for A and B buttons, the rest of buttons are unused.

If you want customization for both players use map=4,5 and gpio= for player 1 and gpio2= for player 2. Example:

# same configuration as map=1,2 but manually:
sudo modprobe mk_arcade_joystick_rpi map=4,5 gpio=4,17,27,22,10,9,25,24,23,18,15,14,2 gpio2=11,5,6,13,19,26,21,20,16,12,7,8,3

# If you use a TFT and want two players, you can´t use all gpios.
# Example with two players and only axes, A and B buttons
sudo modprobe mk_arcade_joystick_rpi map=4,5 gpio=4,17,27,22,-1,-1,25,24,-1,-1,-1,-1,-1 gpio2=11,5,6,13,19,-1,-1,20,16,-1,-1,-1,-1,-1

The GPIO joystick 1 events will be reported to the file "/dev/input/js0" and the GPIO joystick 2 events will be reported to "/dev/input/js1"

Open /etc/modules :

sudo nano /etc/modules

and add the line you use to load the driver :

mk_arcade_joystick_rpi

Then create the file /etc/modprobe.d/mk_arcade_joystick.conf :

sudo nano /etc/modprobe.d/mk_arcade_joystick.conf

and add the module configuration :

options mk_arcade_joystick_rpi map=1,2

Use the following command to test joysticks inputs :

jstest /dev/input/js0

• gamecon_gpio_rpi by marqs
• RetroPie-Setup by petRockBlog
• Low Level Programming of the Raspberry Pi in C by Pieter-Jan