实现自定义的USB编程。启用了D12的端

点1和端点2，端点1为中断传输，最大包为16字节，查询间隔为10ms。端点2为批量

传输，最大包为64字节。端点1的输出第一个字节为控制END USB板上的LED的，每个

bit代表一个LED，为1时表示对应的LED亮。端点1的输入第一个字节为返回的开关

状态，每个bit代表一个按键，为时表示对应的按键按下。输出端点2的数据通过串

口发送出去，串口接收到的数据通过端点2返回。-Implement custom USB programming. D12-enabled endpoint 1 and endpoint 2, Endpoint 1 interrupt transmission, maximum packet is 16 bytes, the query interval is 10ms. Endpoint 2 is bulk transfer, maximum packet is 64 bytes. Endpoint 1 output of the first byte of the control END USB board LED, each bit represents a LED, to 1 indicates that the corresponding LED lights up. Endpoint 1 is the first byte of the input switching status is returned, each bit represents a key, too indicates that the corresponding button is pressed. The data output terminal 2 sent via the serial port, serial data received via endpoint 2 return.