单片机SPI作为从设备通信总结.doc

单片机的spi作为从设备进行通信这里运行的实例是单片机作为从设备，采用arm9作为主设备进行spi通信。arm9作为主设备，spi的通信速率最低为500k，单片机采用nec 的78f1166，晶振采用11.0592mhz时spi通信速率可以达到500k。速率匹配上没有问题。主从设备之间采用的通信协议为dl/645.这里有一个问题，协议的收发数据帧的长度是不确定的。这就涉及到主设备需要读多少个字节的数据。根据实际应用。645规约实际通信时数据帧不会超过100个字节。所以这里解决的方案是，主设备发送命令后，等待200ms后主设备开始抄读数据。这里之所以等待200ms，是因为从设备需要准备数据。以下是从设备的应用程序：unsigned char*gpcsi01rxaddress;/* csi01 receive buffer address */unsigned shortgcsi01rxlen;/* csi01 receive data length */unsigned shortgcsi01rxcnt;/* csi01 receive data count */unsigned char*gpcsi01txaddress;/* csi01 send buffer address */unsigned shortgcsi01txlen;/* csi01 send data length */unsigned shortgcsi01txcnt;/* csi01 send data count */#define bufferlen 200unsigned char spi_rx_bufferbufferlen;unsigned char txflag,rxflag;unsigned char data;unsigned long count = 0;void csi01_init( void )/* csi01 initial setting */ st0 |= sau_ch1_stop_trg_on;/* csi01 disable */csimk01 = 1;/* intcsi01 disable */csiif01 = 0;/* intcsi01 if clear */sir01 = sau_sirmn_fectmn | sau_sirmn_pectmn | sau_sirmn_ovctmn;/* error flag clear */smr01 = sau_smrmn_initialvalue | sau_clock_mode_ti0n | sau_trigger_software | sau_csi | sau_buffer_empty;/sau_transfer_end;scr01 = sau_reception_transmission | sau_timing_4 | sau_msb | sau_length_8;sdr01 = 0;so0&= sau_ch1_data_output_1;/* csi01 so initial level */soe0 |= sau_ch1_output_enable;/* csi01 output enable */* intcsi01 priority low */csipr101 = 0;csipr001 = 0;/* si01 pin setting */pm4 |= 0x10;/* so01 pin setting */p4 |= 0x20;pm4 &= 0x20;/* sck01 pin setting */pm4 |= 0x08;/=void csi01_start( void )csimk01 = 0;/* intcsi01 enable */ss0 |= sau_ch1_start_trg_on;/* csi01 enable */ /gpcsi01rxaddress = spi_rx_buffer;/接收数据指针指向spi_rx_buffer第一个字节 /gcsi01rxcnt = 0;/接收数据个数清零 /gcsi01txcnt = 0;/发送数据个数清零 /setsendflag(sendend);/启动时处于接收状态 /setreceiveflag(receiving);/启动后还没有接收数据/=void csi01_stop( void )st0 |= sau_ch1_stop_trg_on;/* csi01 disable */csimk01 = 1;/* intcsi01 disable */csiif01 = 0;/* intcsi01 if clear */=unsigned char spi_send_data(unsigned char *buffer,unsigned char lenth) gpcsi01txaddress = buffer; gcsi01txcnt = lenth - 1; smr01 |= 0x0001;/add by haolj sio01 = buffer0; setsendflag(sending); while(sendend != check_send_flag() ;/ostimedly(10); return lenth;/=unsigned char spi_receive_data(unsigned char *buffer,unsigned char lenth) unsigned char ack; ack = 0; while(check_receive_flag() = receiving) if(gcsi01rxcnt ack) & gcsi01rxcnt=bufferlen) ack = gcsi01rxcnt; ostimedly(1); else setreceiveflag(receivend); memcpy(buffer,spi_rx_buffer,gcsi01rxcnt); ack = gcsi01rxcnt; gcsi01rxcnt = 0; gpcsi01rxaddress = spi_rx_buffer; return ack; /=#pragma vector = intcsi01_vect_interrupt void md_intcsi01( void ) if( sending = check_send_flag() ) if(gcsi01txcnt = 0) smr01 &= sau_buffer_empty;/add by haolj sio01 = 0xee; setsendflag(sendend); gpcsi01rxaddress = spi_rx_buffer; gcsi01rxcnt = 0; return ; data = sio01; gpcsi01txaddress+;sio01 = *gpcsi01txaddress;gcsi01txcnt-; else data = sio01; sio01 = 0xee; if(gpcsi01rxaddress - spi_rx_buffer) bufferlen) *gpcsi01rxaddress = data; gpcsi01rxaddress +; gcsi01rxcnt +; setreceiveflag(receiving); else setreceiveflag(receivend); gpcsi01rxaddress = spi_rx_buffer; unsigned char check_send_flag(void) return txflag;/=unsigned char check_receive_flag(void) return rxflag;/=void setreceiveflag(unsigned char rflag) rxflag = rflag;/=void sets