Joystick

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Introduction

Joystick can be a good device to play some games or to use graphical interface. Linux has an interface for it named joydev, to use it select joydev in linux configuration :

$ make linux26-menuconfig

then select in menu:

Device Drivers  --->
    Input device support  --->
            <*>   Joystick interface

To use it on the target, node has to be made :

cd /dev
rm js*
mkdir input
mknod input/js0 c 13 0
mknod input/js1 c 13 1
mknod input/js2 c 13 2
mknod input/js3 c 13 3
ln -s input/js0 js0
ln -s input/js1 js1
ln -s input/js2 js2
ln -s input/js3 js3

Test the joystick

Two programs named jstest and jscal wrote by Vojtech Pavlik can be use to test and calibrate the joystick. To use it select joysticktest package in buildroot :

$ make menuconfig

Package Selection for the target  --->
    [*] joysticktest  

To test the joystick on platform, just launch jstest with /dev/jstx argument :

$ jstest /dev/input/js0
Joystick (Austria Microsystem as5011 joystick) has 2 axes and 1 buttons. Driver version is 2.1.0.
Testing ... (interrupt to exit)
Axes:  0: 32767  1: 32767 Buttons:  0:off

Joystick can be calibrated with jscal command :

# jscal -c /dev/input/js0
Joystick has 2 axes and 1 buttons.
Correction for axis 0 is broken line, precision is 0.
Coeficients are: 42, 42, 2147483647, -5835375
Correction for axis 1 is broken line, precision is 0.
Coeficients are: 59, 59, -24402479, -4473788

Calibrating precision: wait and don't touch the joystick.
Done. Precision is:                                             
Axis: 0:     0
Axis: 1:     0

Move axis 0 to minimum position and push any button.
Axis 0:       69
Hold ... OK.                                                                  
Move axis 0 to center position and push any button.
Axis 0:       61
Hold ... OK.                                                                  
Move axis 0 to maximum position and push any button.
Axis 0:     -118
Hold ... OK.                                                                  
Move axis 1 to minimum position and push any button.
Axis 1:      101
Hold ... OK.                                                                  
Move axis 1 to center position and push any button.
Axis 1:       63
Hold ... OK.                                                                  
Move axis 1 to maximum position and push any button.
Axis 1:      -60
Hold ... OK.                                                                  

Setting correction to:
Correction for axis 0: broken line, precision: 0.
Coeficients: 61, 61, -67106816, -2949750
Correction for axis 1: broken line, precision: 0.
Coeficients: 63, 63, -14127751, -4364671

Links

• Linux kernel code documentation