最近做的项目中涉及了IIC总线的运用 IIC总线的运用范围十分广泛 写下博客记录 IIC总线延时 大于4.7us #define Decoded_iic_delay() \ {\ Decoded_iic_DELAY_TMP=Decoded_iic_DELAY_
LUE;\ while(--Decoded_iic_DELAY_TMP);\ } 初始化 void Decoded_iic_init() { Decoded_iic_SCL=1; Decoded_iic_delay(); Decoded_iic_SDA=1; Decoded_iic_delay(); } 开始信号 void Decoded_iic_start() { Decoded_iic_SDA=1; Decoded_iic_delay(); //Myputchar(Decoded_iic_SDA); Decoded_iic_SCL=1; Decoded_iic_delay(); //Myputchar(Decoded_iic_SCL); Decoded_iic_SDA=0; Decoded_iic_delay(); //Myputchar(Decoded_iic_SDA); Decoded_iic_SCL=0; Decoded_iic_delay(); //Myputchar(Decoded_iic_SCL); } 写时序 void Decoded_iic_write(uchar dat) { uchar idata t=8; while(t--) { Decoded_iic_SDA=(bit)(dat&0x80); dat<<=1; Decoded_iic_SCL=1; Decoded_iic_delay(); Decoded_iic_SCL=0; Decoded_iic_delay(); } } 读时序 uchar Decoded_iic_read() { uchar dat=0; uchar t=8; //Myputchar(dat); Decoded_iic_SDA=1;读之前SDA拉高 while(t--) { Decoded_iic_SCL=1; Decoded_iic_delay(); dat <<= 1;一定要先移位后读 如果先读后移位会挤掉最高位 if(Decoded_iic_SDA) { dat |= 0x01; } Decoded_iic_SCL=0; Decoded_iic_delay(); } return dat; } 获取ACK bit Decoded_iic_getack() { bit ack; Decoded_iic_SDA=1;SDA为高释放总线 Decoded_iic_delay(); Decoded_iic_SCL=1; Decoded_iic_delay(); ack=Decoded_iic_SDA; Decoded_iic_SCL=0; Decoded_iic_delay(); return ack; } 发送ACK void Decoded_iic_putack(bit ack) { Decoded_iic_SDA=ack; Decoded_iic_SCL=1; Decoded_iic_delay(); Decoded_iic_SCL=0; Decoded_iic_delay(); } 结束信号 void Decoded_iic_stop() { uint t=Decoded_iic_WAIT_VALUE; Decoded_iic_SDA=0; Decoded_iic_delay(); Decoded_iic_SCL=1; Decoded_iic_delay(); Decoded_iic_SDA=1; Decoded_iic_delay(); while(t--); } 综合发送 bit Decoded_iic_puts(unsigned char SlaveAddr,uchar *dat,unsigned int Length) { if ( Length == 0 ) return 0; Decoded_iic_start(); Decoded_iic_write(SlaveAddr);发送地址 if ( Decoded_iic_getack() ) { Decoded_iic_stop(); return 1; } 发送数据 do { Decoded_iic_write(*dat++); if ( Decoded_iic_getack() ) { //Myputchar('c'); break; } } while ( --Length != 0 ); Decoded_iic_stop(); if ( Length == 0 ) { //Myputchar('a'); return 0; } else { //Myputchar('b'); return 1; } } 综合接收数据 bit Decoded_iic_gets(unsigned char SlaveAddr,uchar *dat,unsigned int Length) { if(!Length) return 0; Decoded_iic_start(); Decoded_iic_write(SlaveAddr+1);发送地址+1 +1是读的意思 if(Decoded_iic_getack()) { Decoded_iic_stop(); return 1; } for (;;) { *dat++ = Decoded_iic_read(); if ( --Length == 0 ) { Decoded_iic_putack(1);发送非ACK break; } Decoded_iic_putack(0);发送ACK } //接收完毕，停止I2C总线，并返回结果 Decoded_iic_stop(); return 0; }
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