Linux操做USB手柄

Linux控制原理

  Linux C控制JoyStick的比較簡單，首先在JoyStick在Linux 安裝好驅動後會在/dev/input生成js0.對其設備控制，就是讀取相應的結構來判斷用戶輸入哪一些指令.

當用戶操做手柄時，驅動發送js_event的結構給應用程序以通知用戶做了哪一些操做。js_event有以下定義

struct js_event {
unsigned int time; /* event timestamp in milliseconds */
short value; /* value */
unsigned char type; /* event type */
unsigned char number; /* axis/button number */
};

手柄按鈕分佈

當按下1-4號鍵會發送type = 1 (Button),number  = 0- 3的值

按下 select 返回 type = 1,number = 8,

按下 start 返回 type = 1,number  = 9

當按下左側四個鍵.有兩種狀況，當按ANALOG鍵時（即紅燈亮起）。它返回以下四個值

   js_event 的type 爲2.(AXIS).

     上鍵/下鍵:number  = 6，二者的區別在於value,上鍵按下value = -32767,鬆開等於 = 0.

                        下健按下value = 32767,鬆開等於 0

,

     左/右鍵:number  = 5二者的區別在於value,左鍵按下value = -32767,鬆開等於 = 0.

                        右健按下value = 32767,鬆開等於 0

當ANALOG鍵關閉時（即紅燈滅時）.

    上鍵/下鍵:number  =1,    左/右鍵:number  =0.

下面的轉動控制桿相對比較複雜。

     左側旋轉杆,向上撥 type = 2,number = 1,value = -32767

              向下撥  type = 2,number = 1,value = 32767

               向左  type = 2,number = 2,value = -32767

               向右  type = 2,number = 2,value = 32767

      若是是偏於某個方向，即於返回最接近的鍵的值type/number，可是value有介於0到最大值之間。

  當選旋轉時，至關於向系統傳送一系列的value漸變的jse_event。

      右側轉動控制桿是

            向上type = 2,number = 2 ,value =-32767

            向下撥  type = 2,number = 2,value = 32767

            向左 type = 2,number = 3,value = -32767

            向右  type = 2,number = 3,value = 32767

完整的控制代碼

這是從網上下載的演示代碼，這是調整事後正確誤的

JoyStick.h

/*
    (C) Copyright 2007,2008, Stephen M. Cameron.
    This file is part of wordwarvi.
    wordwarvi is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
    wordwarvi is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    GNU General Public License for more details.
    You should have received a copy of the GNU General Public License
    along with wordwarvi; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#ifndef __JOYSTICK_H__
#define __JOYSTICK_H__
#define JOYSTICK_DEVNAME "/dev/input/js0"
#define JS_EVENT_BUTTON 0x01 /* button pressed/released */
#define JS_EVENT_AXIS 0x02 /* joystick moved */
#define JS_EVENT_INIT 0x80 /* initial state of device */
struct js_event {
unsigned int time; /* event timestamp in milliseconds */
short value; /* value */
unsigned char type; /* event type */
unsigned char number; /* axis/button number */
};
struct wwvi_js_event {
int button[11];
int stick1_x;
int stick1_y;
int stick2_x;
int stick2_y;
};
extern int open_joystick(char *joystick_device);
extern int read_joystick_event(struct js_event *jse);
extern void set_joystick_y_axis(int axis);
extern void set_joystick_x_axis(int axis);
extern void close_joystick();
extern int get_joystick_status(struct wwvi_js_event *wjse);
#endif


JoyStick.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "joystick.h"
static int joystick_fd = -1;
int open_joystick(char *joystick_device)
{
    joystick_fd = open(joystick_device, O_RDONLY | O_NONBLOCK); /* read write for force feedback? */
if (joystick_fd < 0)
return joystick_fd;
/* maybe ioctls to interrogate features here? */
return joystick_fd;
}
int read_joystick_event(struct js_event *jse)
{
int bytes;
    bytes = read(joystick_fd, jse, sizeof(*jse));
if (bytes == -1)
return 0;
if (bytes == sizeof(*jse))
return 1;
printf("Unexpected bytes from joystick:%d\n", bytes);
return -1;
}
void close_joystick()
{
close(joystick_fd);
}
int get_joystick_status(struct wwvi_js_event *wjse)
{
int rc;
struct js_event jse;
if (joystick_fd < 0)
return -1;
// memset(wjse, 0, sizeof(*wjse));
while ((rc = read_joystick_event(&jse) == 1)) {
        jse.type &= ~JS_EVENT_INIT; /* ignore synthetic events */
if (jse.type == JS_EVENT_AXIS) {
switch (jse.number) {
case 0: wjse->stick1_x = jse.value;
break;
case 1: wjse->stick1_y = jse.value;
break;
case 2: wjse->stick2_x = jse.value;
break;
case 3: wjse->stick2_y = jse.value;
break;
default:
break;
}
} else if (jse.type == JS_EVENT_BUTTON) {
if (jse.number < 10) {
switch (jse.value) {
case 0:
case 1: wjse->button[jse.number] = jse.value;
break;
default:
break;
}
}
}
}
// printf("%d\n", wjse->stick1_y);
return 0;
}
#if 1
/* a little test program */
int main(int argc, char *argv[])
{
int fd, rc;
int done = 0;
struct js_event jse;
    fd = open_joystick("/dev/js0");
if (fd < 0) {
printf("open failed.\n");
exit(1);
}
while (!done) {
        rc = read_joystick_event(&jse);
usleep(1000);
if (rc == 1) {
printf("Event: time %8u, value %8hd, type: %3u, axis/button: %u\n",
                jse.time, jse.value, jse.type, jse.number);
}
}
}
#endif

轉載連接：http://blog.chinaunix.net/uid-20587912-id-405148.html