原创 USB游戏手柄的实现

经过几天的忙活，终于把GamePad调通了。

硬件用的是电脑圈圈的USB开发板STC89C52+PDIUSBD12.

由于按键有限，所以只用了上、下、左、右四个方向跟四个按键，晚上还玩了会kof97.

首先把hid的子类代码跟协议代码都置为0.

接着，修改HID的报告描述符。

code char JoyStickReportDescriptor[54] = {
    0x05, 0x01,                    // USAGE_PAGE (Generic Desktop)

  //用途，GamePad
    0x09, 0x05,                    // USAGE (Game Pad)

  //集合
    0xa1, 0x01,                    // COLLECTION (Application)

  //指针设备
    0x09, 0x01,                    //   USAGE (Pointer)

  //集合
    0xa1, 0x00,                    //   COLLECTION (Physical)

   //X座标跟Y座标
    0x09, 0x30,                    //     USAGE (X)
    0x09, 0x31,                    //     USAGE (Y)

   //一共有九个方向3*3
    0x15, 0x00,                    //     LOGICAL_MINIMUM (0)
    0x25, 0x02,                    //     LOGICAL_MAXIMUM (2)

   //X/Y各用两位来表示
    0x75, 0x02,                    //     REPORT_SIZE (2)
    0x95, 0x02,                    //     REPORT_COUNT (2)
    0x81, 0x02,                    //     INPUT (Data,Var,Abs)
    0xc0,                          //   END_COLLECTION

   //高四位填充
    0x75, 0x01,                    //   REPORT_SIZE (1)
    0x95, 0x04,                    //   REPORT_COUNT (4)
    0x81, 0x03,                    //   INPUT (Cnst,Var,Abs)

   //四个按键
    0x05, 0x09,                    //   USAGE_PAGE (Button)
    0x19, 0x01,                    //   USAGE_MINIMUM (Button 1)
    0x29, 0x04,                    //   USAGE_MAXIMUM (Button 4)
    0x15, 0x00,                    //   LOGICAL_MINIMUM (0)
    0x25, 0x01,                    //   LOGICAL_MAXIMUM (1)
    0x75, 0x01,                    //   REPORT_SIZE (1)
    0x95, 0x04,                    //   REPORT_COUNT (4)
    0x81, 0x02,                    //   INPUT (Data,Var,Abs)

    //高四位填充
    0x75, 0x01,                    //   REPORT_SIZE (1)
    0x95, 0x04,                    //   REPORT_COUNT (4)
    0x81, 0x03,                    //   INPUT (Cnst,Var,Abs)
    0xc0                           //   END_COLLECTION
};

数据格式：

Byte1    bit7-bit4 常量填充   bi3-bit0 X/Y座标

Byte2    bit7-bit4 常量填充   bi3-bit0 四个按键状态