joy(4) · carta

NAME

joy – joystick device driver

SYNOPSIS

To link into the kernel: device joy

To load as a kernel loadable module:

kldload joy

In /boot/device.hints: hint.joy.0.at="isa" hint.joy.0.port="0x201"

#include <sys/joystick.h>

DESCRIPTION

The joystick device driver allows applications to read the status of the PC joystick.

This device may be opened by only one process at a time.

The joystick status is read from a structure via a read() call. The structure is defined in the header file as follows:

	struct joystick {
		int x;         /* x position */
		int y;         /* y position */
		int b1;	       /* button 1 status */
		int b2;	       /* button 2 status */
	};

Positions are typically in the range 0-2000.

One line perl example:

perl -e 'open(JOY,"/dev/joy0")||die;while(1)
{sysread(JOY,$x,16);@j=unpack("iiii",$x);print "@j\n";sleep(1);}'

ioctl calls

Several ioctl() calls are also available. They take an argument of type int *

JOY_SETTIMEOUT int, *limit: Set the time limit (in microseconds) for reading the joystick status. Setting a value too small may prevent to get correct values for the positions (which are then set to -2147483648), however this can be useful if one is only interested by the buttons status.
JOY_GETTIMEOUT int, *limit: Get the time limit (in microseconds) used for reading the joystick status.
JOY_SET_X_OFFSET int, *offset: Set the value to be added to the X position when reading the joystick status.
JOY_SET_Y_OFFSET int, *offset: Set the value to be added to the Y position when reading the joystick status.
JOY_GET_X_OFFSET int, *offset: Get the value which is added to the X position when reading the joystick status.
JOY_GET_Y_OFFSET int, *offset: Get the value which is added to the Y position when reading the joystick status.

TECHNICAL SPECIFICATIONS

The pinout of the DB-15 connector is as follow:

  1  XY1 (+5v)
  2  Switch 1
  3  X1 (potentiometer #1)
  4  Switch 1 (GND)
  5  Switch 2 (GND)
  6  Y1 (potentiometer #2)
  7  Switch 2
  8  N.C.
  9  XY2 (+5v)
 10  Switch 4
 11  X2 (potentiometer #3)
 12  Switch 3&4 (GND)
 13  Y2 (potentiometer #4)
 14  Switch 3
 15  N.C.

Pots are normally 0-150k variable resistors (0-100k sometimes), and according to the IBM techref, the time is given by Time = 24.2e-6s + 0.011e-6s * R/Ohms

FILES

/dev/joy?: joystick device files

HISTORY

The joystick driver appeared in FreeBSD 2.0.5.

AUTHORS

Jean-Marc Zucconi ⟨[email protected]⟩