Linux控制原理

Linux C控制JoyStick的比较简单，首先在JoyStick在Linux 安装好驱动后会在/dev/input生成js0.对其设备控制，就是读取相应的结构来判断用户输入哪一些指令.

当用户操作手柄时，驱动发送js_event的结构给应用程序以通知用户作了哪一些操作。js_event有如下定义

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

手柄按钮分布

当按下1-4号键会发送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

当按下左侧四个键.有两种情况，当按ANALOG键时（即红灯亮起）。它返回如下四个值

js_event 的type 为2.(AXIS).

上键/下键:number  = 6，两者的区别在于value,上键按下value = -32767,松开等于 = 0.

下健按下value = 32767,松开等于 0

,

左/右键:number  = 5两者的区别在于value,左键按下value = -32767,松开等于 = 0.

右健按下value = 32767,松开等于 0

当ANALOG键关闭时（即红灯灭时）.

上键/下键:number  =1,    左/右键:number  =0.

下面的转动控制杆相对比较复杂。

左侧旋转杆,向上拨 type = 2,number = 1,value = -32767

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

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

向右  type = 2,number = 2,value = 32767

如果是偏于某个方向，即于返回最接近的键的值type/number，但是value有介于0到最大值之间。

当选旋转时，相当于向系统传送一系列的value渐变的jse_event。

右侧转动控制杆是

向上type = 2,number = 2 ,value =-32767

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

向左 type = 2,number = 3,value = -32767

向右  type = 2,number = 3,value = 32767

完整的控制代码

这是从网上下载的演示代码，这是调整过后正确误的

JoyStick.h

/* &nbsp;&nbsp;&nbsp; (C) Copyright 2007,2008, Stephen M. Cameron. &nbsp;&nbsp;&nbsp; This file is part of wordwarvi. &nbsp;&nbsp;&nbsp; wordwarvi is free software; you can redistribute it and/or modify &nbsp;&nbsp;&nbsp; it under the terms of the GNU General Public License as published by &nbsp;&nbsp;&nbsp; the Free Software Foundation; either version 2 of the License, or &nbsp;&nbsp;&nbsp; (at your option) any later version. &nbsp;&nbsp;&nbsp; wordwarvi is distributed in the hope that it will be useful, &nbsp;&nbsp;&nbsp; but WITHOUT ANY WARRANTY; without even the implied warranty of &nbsp;&nbsp;&nbsp; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the &nbsp;&nbsp;&nbsp; GNU General Public License for more details. &nbsp;&nbsp;&nbsp; You should have received a copy of the GNU General Public License &nbsp;&nbsp;&nbsp; along with wordwarvi; if not, write to the Free Software &nbsp;&nbsp;&nbsp; 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) { &nbsp;&nbsp;&nbsp; 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; &nbsp;&nbsp;&nbsp; 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)) { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 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; &nbsp;&nbsp;&nbsp; fd = open_joystick("/dev/js0"); if (fd < 0) { printf("open failed.\n"); exit(1); } while (!done) { &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; rc = read_joystick_event(&jse); usleep(1000); if (rc == 1) { printf("Event: time %8u, value %8hd, type: %3u, axis/button: %u\n", &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; jse.time, jse.value, jse.type, jse.number); } } } #endif

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