[原创]USB通信协议的理解流程描述

《[原创]USB通信协议的理解流程描述》由会员分享，可在线阅读，更多相关《[原创]USB通信协议的理解流程描述（16页珍藏版）》请在装配图网上搜索。

1、原创 USB通信协议的理解,流程 ,描述做了一段时间的USB 方面的开发，虽然是现成的方案，我们只需要搞清楚它的架构, 再添加我们的代码就行了。空闲之余，研究了一下USB 通信过程，也把82A851R部分的汇编代码重新用C 语言描述了一篇（仅是描述，不代表能真正运行）。发现汇编代码条理性太在太差了，不好读。一把C 语言的代码一写，马上觉得清楚很多。废话少说，开始贴图，贴代码。下面是将一些函数重新用C 语言描述了一遍#define BYTE unsigned char/*/基本定义函数/*BYTE FIFO_RD_CHECK(BYTE num)BYTE FIFO_FLAG=0;UCC|=num;

2、/选择 Endpoint,0,1,2,3,4,MISC&=0xf8;/低 3 位置 0MISC|=0X00;/TX位置 0;Delay_3us();MISC|=0X01;/Set RequestDelay_28us();if(MISC&0X40!=0)FIFO_FLAG=0x0f;/READYif(MISC&0x80!=0)FIF0_FLAG&=0xf0;/Len0 DetectedMISC&=0xfe;/clear REQreturn FIFO_FLAG;BYTE FIFO_WR_CHECK(BYTE num)BYTE FIFO_FLAG=0;/后 4 位表示 Ready 位 ,前四位表示L

3、en0 位的状态是否有被设置UCC|=num;/选择 Endpoint,0,1,2,3,4,MISC&=0xf8;/低 3 位置 0MISC|=0X02;/TX位置 0;Delay_3us();MISC|=0X01;/Set RequestDelay_28us();if(MISC&0X40!=0)FIFO_FLAG=0x0f;/READYif(MISC&0x80!=0)FIF0_FLAG&=0xf0;/Len0 DetectedMISC&=0xfe;/clear REQreturn FIFO_FLAG;void Read_FIFO(BYTE *Fifo_Addr,BYTE Fifo_Size,

4、BYTE *buffer)int i=0;MISC|=0x01;/Set Requestfor(i=0;iFifo_Size;i+)bufferi=Fifo_Addr0;/从 FIFO 地址取值Delay_28us();if(MISC&0x40=0)break;/Not ReadyMISC=0X02;/改变 TX 位状态Delay_3us();MISC&=0XFE;/Clear Requestvoid Write_FIFO(BYTE *Fifo_Addr,BYTE SendLenth,BYTE *buffer)int i=0;MISC|=0X01;/Set Requestfor(i=0;ida

5、ta_start0)/请求的数据超出ROM 数据return;data_count=buffer6;if(MISC&0x40!=0)/是控制指令return;if(data_count=0)Send_Hand_Shake();return;/开始真正的control_readwhile(1)if(bFlag_RD_HTable=0)/Read Low BytebFlag_RD_HTable=1;bufferi=(BYTE )*rom_dataptr;/取其低位i+;data_count-;/全局变量 ,要发送的总长度if(data_count8;/取其高位rom_dataptr+;/将 ROM

6、 指针前移if(bufferi=0x3f)continue;elsei+;if(data_count=0X81 0010 0000B if(temp&STALL=TRUE)/ 要检测的位置 1buffer0=1;else buffer0=0;buffer1=0;while(1)if(Check_Real_Cmd()=TRUE) break;/ 估计是 Len0=1, 结束会话 if(FIFO_WR_CHECK(0)=FALSE) continue;Write_FIFO(Fifo_0_Addr,FIFO_SendLen,buffer);/*/GetConfiguration():设置配置的函数/

7、*void GetConfiguration(BYTE *buffer,BYTE USB_Configuration)BYTE FIFO_SendLen;buffer0=USB_Configuration;FIFO_SendLen=0x01;while(1)if(Check_Real_Cmd()=TRUE) return;if(FIFO_WR_CHECK(0)&0x0f!=0)/Fifo Readybreak;Write_FIFO(Fifo_0_Addr,FIFO_SendLen,buffer);/*/GetInterface():获取 Interface接口的函数/*void GetInte

8、rface(BYTE USB_Interface_Alt,BYTE *buffer)BYTE FIFO_SendLen;buffer0=USB_Interface_Alt;FIFO_SendLen=0x01;while(1)if(Check_Real_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,FIFO_SendLen,buffer)/*/SetReport():设置 Report的函数/*BYTE SetReport(BYTE *buffer)BYTE FIFO

9、_wValueH=buffer3;BYTE nCmdIndex1;if(FIFO_wValueH=0x02)/set_output_reportif(buffer4!=0x03)/check interfaceSTALL|=0x01;/ENPOINT0 Errorreturn;if(buffer6!=0x08)/FIFO_wLengthL,check lengthSTALL|=0x01;/ENPOINT0 Errorreturn;nCmdIndex1=0x21;return nCmdIndex1;/返回命令索引号/*/SetCur():设置当前信息的函数/包括 VolumeControl,Mu

10、teControl/*void SetCur(BYTE *buffer)/;21 01if(buffer3=0x01)/MUTE_CONTROLMuteControl();else if(buffer3=0x02)/VOLUME_CONTROLVolumeControl();elseSTALL0|=0x01;BYTE MuteControl(BYTE *buffer) /21 01 00 01,if have more feature , the state must be modify!BYTE nCmdIndex1;if(buffer5=0x02)/FIFO_wIndexH,MuteCon

11、trol_SetSpeaker();nCmdIndex1=0x18;return nCmdIndex1;else if(buffer5=0x06)/MuteControl_SetMic();nCmdIndex1=0x19;return nCmdIndex1;BYTE VolumeControl(BYTE *buffer)BYTE nCmdIndex1;if(buffer5=0x02)/FIFO_wIndexH,VolumeControl_SetSpeaker()nCmdIndex1=0x28;return nCmdIndex1;else ifbuffer5=0x06)nCmdIndex1=0x

12、29;return nCmdIndex1;/*/GetMin():获取各种最小信息的函数/包括 GetMin_SetSpeaker,GetMin_SetMic/*void GetMin(BYTE *buffer)if(buffer5=0x02)/FIFO_wIndexHGetMin_SetSpeaker();else if(buffer5=0x06)GetMin_SetMic();elseSTALL|=0X01;void GetMin_SetSpeaker(BYTE *buffer)buffer0=0x00;buffer1=0xe0;/Min_Volumewhile(1)if(Check_Re

13、al_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,0x02,buffer)void GetMin_SetMic(BYTE *buffer)buffer0=0x00;buffer1=0x00;/MIC_Min_Volumewhile(1)if(Check_Real_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,0x02,buffer)/*

14、/GetMax():获取各种最大信息的函数/包括 Speaker,Mic/*void GetMax(BYTE *buffer)if(buffer5=0x02)/FIFO_wIndexHGetMax_SetSpeaker();else if(buffer5=0x06)GetMax_SetMic();elseSTALL0|=0x01;void GetMax_SetSpeaker(BYTE *buffer)buffer0=0x00;buffer1=0x0c;/Max_Volumewhile(1)if(Check_Real_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0

15、xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,0x02,buffer)void GetMax_SetMic(BYTE *buffer)buffer0=0x00;buffer1=0x0c;/MIC_Max_Volumewhile(1)if(Check_Real_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,0x02,buffer)/*/GetRes():/*void GetRes(BYTE *buffer)buffe

16、r0=0x00;buffer1=0x01;while(1)if(Check_Real_Cmd()=TRUE)return;if(FIFO_WR_CHECK(0)&0xff=0) continue;/Not ReadyWrite_FIFO(Fifo_0_Addr,0x02,buffer)/*/GetCur():/*void GetCur(BYTE *buffer)BYTE FIFO_wLengthL=buffer6;BYTE FIFO_wIndexH=buffer5;BYTE FIFO_SendLen;FIFO_SendLen=FIFO_wLengthL;if(FIFO_SendLen=0x01

17、)GetCurMute();else if(FIFO_SendLen=0x02)GetCur_Volume();elseSTALL|=0x01;void GetCur_Mute(BYTE *buffer)if(FIFO_wIndexH=0x02)GetCur_Mute_Speaker();else if(FIFO_wIndexH=0x06)GetCur_Mute_Mic();elseSTALL|=0x01;void GetCur_Mute_Mic(BYTE *buffer)if(bFlag_Mic_Mute=TRUE)buffer0=0x01;elsebuffer0=0x00;while(1)

18、if(Check_Real_Cmd()=TRUE) return;if(FIFO0_WR_CHECK()&0x0f=0) continue;/未准备好elsebreak;Write_FIFO(Fifo_0_Addr,0x01,buffer);void GetCur_Mute_Speaker(BYTE *buffer)if(bFlag_Audio_Mute=TRUE)buffer0=0x01;elsebuffer0=0x00;while(1)if(Check_Real_Cmd()=TRUE) return;if(FIFO0_WR_CHECK()&0x0f=0) continue;/未准备好els

19、ebreak;Write_FIFO(Fifo_0_Addr,0x01,buffer);void GetCur_Volume(BYTE *buffer)if(buffer5=0x02)/FIFO_wIndexHGetCur_Volume_Speaker();else if(buffer5=0x06)GetCur_Volume_Mic();elseSTALL|=0x01;void GetCur_Volume_Mic(BYTE *buffer)buffer0=0x00;buffer1=PGA_CTRL&0x3f;while(1)if(Check_Real_Cmd()=TRUE) return;if(

20、FIFO0_WR_CHECK()&0x0f=0) continue;/未准备好else break;Write_FIFO(Fifo_0_Addr,0x02,buffer);void GetCur_Volume_Speaker(BYTE *buffer,BYTE VolumeL_Save,BYTE VolumeH_Save)buffer0=VolumeH_Save;buffer1=VolumeL_Save;while(1)if(Check_Real_Cmd()=TRUE) return;if(FIFO0_WR_CHECK()&0x0f=0) continue;/未准备好else break;Wr

21、ite_FIFO(Fifo_0_Addr,0x02,buffer);/*/Const String常量/*BYTE device_desc_table=/18 bytesWORD0x0112,/descriptor type (device descriptor) , size of descriptor (18 bytes)WORD0x0110,/USB spec release (ver 1.1)WORD0x0000,/device sub-class , Communicationdevice classWORD0x0800,/bMaxPacketSize0 maximum packet

22、 size , bDeviceProtocolWORD0x04D9,/vendor ID = 004D9HWORD0x2851,/product version ID (Sample Device)WORD0x0100,/product version ID Device Release CodeWORD0x0201,/product string index , manufacturer string indexWORD0x0103,/number of configurations , serial number string indexBYTE config_desc_table=/9 bytesWORD0x0209,/descriptor type (config descriptor) , size of descriptorWORD0x00D9,/total length of descriptor (D9 H=217 bytes)WORD0x0104,/index of this configuration , 4 interfaceWORD0x3F00,/configuration string indexWORD0x3F80,/configuration attributes (bus supply)WORD0x3FFA,/maxpower (500ma)