ZigBee学习之6无线电2.docx

1、ZigBee学习之6无线电2#1楼主：【原创】ZigBee学习之6无线电2文章发表于：2010-02-05 11:17今天把TI的例子程序里的基本RF看了下，有的地方还没有完全看懂，发上来和大家分享一下/* Filename: basic_rf.c Description: Basic RF library */ /* INCLUDES*/hal_int.h包含了控制中断的宏#include hal_int.h/ Using halMcuWaitUs()，hal_mcu.h中是一些延时函数#include hal_mcu.h /通道编程的宏，以及硬件RF初始化，SECURITY_CCM宏是用来

2、控制安全MAC的#include hal_rf.h#ifdef SECURITY_CCM#include hal_rf_security.h#endif /basic_rf.h中定义了RF配置用的数据结构#include basic_rf.h#ifdef SECURITY_CCM#include basic_rf_security.h#endif #include util.h / Using min()#include string.h /* CONSTANTS AND DEFINES*/ / Packet and packet part lengths#define PKT_LEN_MIC

3、 8#define PKT_LEN_SEC PKT_LEN_UNSEC + PKT_LEN_MIC#define PKT_LEN_AUTH 8#define PKT_LEN_ENCR 24 / Packet overhead (frame control field, sequence number, PAN ID,/ destination and source) + (footer)/ Note that the length byte itself is not included included in the packet length/MPDU的长度宏，（2字节幀控制域 + 1字节数

4、据序列号 + 2字节PAN ID + 2字节目标地址 + 2字节源地址 + 2字节MAC尾）#define BASIC_RF_PACKET_OVERHEAD_SIZE (2 + 1 + 2 + 2 + 2) + (2)/MPDU最大有效载荷的长度（利用FIFO只有128字节空间），BASIC_RF_AUX_HDR_LENGTH 和 BASIC_RF_LEN_MIC是辅助安全头宏定义的长度分别是5和8，可以将其设置为0，即不具备安全功能#define BASIC_RF_MAX_PAYLOAD_SIZE (127 - BASIC_RF_PACKET_OVERHEAD_SIZE - BASIC_RF

5、_AUX_HDR_LENGTH - BASIC_RF_LEN_MIC)/应答帧的长度宏（2字节帧首界定符 + 1字节数据序列号 + 2字节帧校验序列），不包括帧长度域#define BASIC_RF_ACK_PACKET_SIZE 5/MAC帧尾的长度宏#define BASIC_RF_FOOTER_SIZE 2#define BASIC_RF_HDR_SIZE 10 / The time it takes for the acknowledgment packet to be received after the/ data packet has been transmitted.#defi

6、ne BASIC_RF_ACK_DURATION (0.5 * 32 * 2 * (4 + 1) + (1) + (2 + 1) + (2)#define BASIC_RF_SYMBOL_DURATION (32 * 0.5) / The length byte#define BASIC_RF_PLD_LEN_MASK 0x7F /帧控制域/帧类型子域： 000 信标帧/ 001 数据帧/ 010 应答帧/ 011 MAC命令/ 100110 保留/安全允许子域：0 帧无安全保护/ 1 帧采用安全保护/帧待定子域： 0 传输没有附加数据的帧/ 1 当前传输后有附加的数据要发送 /应答请求子域：

7、 0 不需要接收器发送应答帧/ 1 需要接收器发送应答帧/内部PAN子域：决定MAC帧是在内部还是在其他PAN之间发送/ 0 如果目的地址和源地址都存在帧将包括目标和源PAN标志域/ 1 如果目的地址和源地址都存在帧不包括源PAN标志域 /目的地址模式子域：若为0，并且帧类型没有指定这是个应答帧或信标帧且源地址域非0，则暗含此帧发送到PAN协调器将其PAN标志作为源PAN标志域 /源地址模式子域：若为0，且帧类型没有指定这是个应答帧或信标帧，目的地址不为0，则暗含此帧来自PAN协调器，用其PAN标志作为目的PAN标志域 /00 PAN标志器且地址域未提交/01 保留/10 地址域包含16位的短

8、地址/11 地址域包含64位的扩展地址/ Frame control field/16位短地址模式，数据帧，没有安全保护#define BASIC_RF_FCF_NOACK 0x8841#define BASIC_RF_FCF_ACK 0x8861#define BASIC_RF_FCF_ACK_BM 0x0020#define BASIC_RF_FCF_BM (BASIC_RF_FCF_ACK_BM)#define BASIC_RF_SEC_ENABLED_FCF_BM 0x0008 / Frame control field LSB#define BASIC_RF_FCF_NOACK_L

9、LO_UINT16(BASIC_RF_FCF_NOACK)#define BASIC_RF_FCF_ACK_L LO_UINT16(BASIC_RF_FCF_ACK)#define BASIC_RF_FCF_ACK_BM_L LO_UINT16(BASIC_RF_FCF_ACK_BM)#define BASIC_RF_FCF_BM_L LO_UINT16(BASIC_RF_FCF_BM)#define BASIC_RF_SEC_ENABLED_FCF_BM_L LO_UINT16(BASIC_RF_SEC_ENABLED_FCF_BM) / Auxiliary Security header#

10、define BASIC_RF_AUX_HDR_LENGTH 5#define BASIC_RF_LEN_AUTH BASIC_RF_PACKET_OVERHEAD_SIZE + BASIC_RF_AUX_HDR_LENGTH - BASIC_RF_FOOTER_SIZE#define BASIC_RF_SECURITY_M 2#define BASIC_RF_LEN_MIC 8#ifdef SECURITY_CCM#undef BASIC_RF_HDR_SIZE#define BASIC_RF_HDR_SIZE 15#endif / Footer#define BASIC_RF_CRC_OK

11、_BM 0x80 /* TYPEDEFS*/ The receive structtypedef struct uint8 seqNumber; uint16 srcAddr; uint16 srcPanId; int8 length; uint8* pPayload; uint8 ackRequest; int8 rssi; volatile uint8 isReady; uint8 status; basicRfRxInfo_t; / Tx statetypedef struct uint8 txSeqNumber; volatile uint8 ackReceived; uint8 re

12、ceiveOn; uint32 frameCounter; basicRfTxState_t; /兼容IEEE 802.15.4 的MHR（MAC头）（2字节帧控制 + 1字节数据序列号 + 020字节地址信息）/ Basic RF packet header (IEEE 802.15.4)typedef struct uint8 packetLength; uint8 fcf0; / Frame control field LSB uint8 fcf1; / Frame control field MSB uint8 seqNumber; uint16 panId; uint16 destA

13、ddr; uint16 srcAddr; #ifdef SECURITY_CCM uint8 securityControl; uint8 frameCounter4; #endif basicRfPktHdr_t; /* LOCAL VARIABLES*/static basicRfRxInfo_t rxi= 0xFF ; / Make sure sequence numbers arestatic basicRfTxState_t txState= 0x00 ; / initialised and distinct. static basicRfCfg_t* pConfig;static

14、uint8 txMpduBASIC_RF_MAX_PAYLOAD_SIZE+BASIC_RF_PACKET_OVERHEAD_SIZE+1;static uint8 rxMpdu128; /* GLOBAL VARIABLES*/ /* LOCAL FUNCTIONS*/ /* fn basicRfBuildHeader* brief Builds packet header according to IEEE 802.15.4 frame format* param buffer - Pointer to buffer to write the header* destAddr - dest

15、ination short address* payloadLength - length of higher layer payload* return uint8 - length of header*/构造兼容IEEE802.15.4 的帧头static uint8 basicRfBuildHeader(uint8* buffer, uint16 destAddr, uint8 payloadLength) /声明一个指向MAC帧头结构的指针 basicRfPktHdr_t *pHdr; uint16 fcf; pHdr= (basicRfPktHdr_t*)buffer; /paylo

16、adLength为有效载荷的长度，即要发送的数据的长度 / Populate packet header pHdr-packetLength = payloadLength + BASIC_RF_PACKET_OVERHEAD_SIZE; /pConfig为基本配置数据结构 /*typedef struct uint16 myAddr; uint16 panId; uint8 channel; uint8 ackRequest; basicRfCfg_t; */ /pHdr-frameControlField = pConfig-ackRequest ? BASIC_RF_FCF_ACK :

17、BASIC_RF_FCF_NOACK; fcf= pConfig-ackRequest ? BASIC_RF_FCF_ACK : BASIC_RF_FCF_NOACK; /分别得到16位数的低8位和高8位 /#define HI_UINT16(a) (uint16)(a) 8) & 0xFF) /#define LO_UINT16(a) (uint16)(a) & 0xFF) pHdr-fcf0 = LO_UINT16(fcf); pHdr-fcf1 = HI_UINT16(fcf); /得到数据序列 pHdr-seqNumber= txState.txSeqNumber; pHdr-panI

18、d= pConfig-panId; pHdr-destAddr= destAddr; pHdr-srcAddr= pConfig-myAddr; #ifdef SECURITY_CCM / Add security to FCF, length and security header pHdr-fcf0 |= BASIC_RF_SEC_ENABLED_FCF_BM_L; pHdr-packetLength += PKT_LEN_MIC; pHdr-packetLength += BASIC_RF_AUX_HDR_LENGTH; pHdr-securityControl= SECURITY_CO

19、NTROL; pHdr-frameCounter0= LO_UINT16(LO_UINT32(txState.frameCounter); pHdr-frameCounter1= HI_UINT16(LO_UINT32(txState.frameCounter); pHdr-frameCounter2= LO_UINT16(HI_UINT32(txState.frameCounter); pHdr-frameCounter3= HI_UINT16(HI_UINT32(txState.frameCounter); #endif / Make sure bytefields are network

20、 byte order /这里把大的字节放到了前面，但有不是完全按从大到小的顺序排列字节，不知道为什么？ UINT16_HTON(pHdr-panId); UINT16_HTON(pHdr-destAddr); UINT16_HTON(pHdr-srcAddr); /1字节长度，2字节FCF，1字节序列，2字节PanID，2字节目的地址，2字节源地址=10 return BASIC_RF_HDR_SIZE; /* fn basicRfBuildMpdu* brief Builds mpdu (MAC header + payload) according to IEEE 802.15.4* f

21、rame format* param destAddr - Destination short address* pPayload - pointer to buffer with payload* payloadLength - length of payload buffer* return uint8 - length of mpdu*/构造MPDUstatic uint8 basicRfBuildMpdu(uint16 destAddr, uint8* pPayload, uint8 payloadLength) uint8 hdrLength, n; /txMpdu是定义txMpdu

22、BASIC_RF_MAX_PAYLOAD_SIZE+BASIC_RF_PACKET_OVERHEAD_SIZE+1 hdrLength = basicRfBuildHeader(txMpdu, destAddr, payloadLength); /将有效载荷数据放入MPDU单元中 for(n=0;n0) *pData+= RFD; length-; */ /读取MPDU的长度 / Read payload length. halRfReadRxBuf(&pHdr-packetLength,1); /指定MPDU的长度字节的高位默认固定为0，所以去掉高位，得到长度真实值 pHdr-packetL

23、ength &= BASIC_RF_PLD_LEN_MASK; / Ignore MSB / Is this an acknowledgment packet? / Only ack packets may be 5 bytes in total. if (pHdr-packetLength = BASIC_RF_ACK_PACKET_SIZE) /如果只有5个字节长度，则此帧为应答帧 / Read the packet halRfReadRxBuf(&rxMpdu1, pHdr-packetLength); / Make sure byte fields are changed from n

24、etwork to host byte order UINT16_NTOH(pHdr-panId); UINT16_NTOH(pHdr-destAddr); UINT16_NTOH(pHdr-srcAddr); #ifdef SECURITY_CCM UINT32_NTOH(pHdr-frameCounter); #endif rxi.ackRequest = !(pHdr-fcf0 & BASIC_RF_FCF_ACK_BM_L); /条过RSSI指到CRC校验 / Read the status word and check for CRC OK pStatusWord= rxMpdu + 4; / Indicate the successful ACK reception if CRC and sequence number OK