c51_i2c.c

小容量单片机系统的C语言程序结构,极其好用

       
      　
      /********************************************** 
        模拟I2C程序 winavr20050214 
      ***********************************************/ 
      # define F_CPU 4000000UL 

      #include <avr/io.h> 
      #include <avr/delay.h> 

      #define cbi(sfr, bit)         (_SFR_BYTE(sfr) &= ~_BV(bit)) 
      #define sbi(sfr, bit)         (_SFR_BYTE(sfr) |= _BV(bit)) 
      #define bit_is_set(sfr, bit)    (_SFR_BYTE(sfr) & _BV(bit)) 

      //DDR    PORT     
      //0    0    in,high 
      //0    1    in,r 
      //1    0    out=0 
      //1    1    out=1 

      #define sda    0 
      #define scl    1 
      #define I2C        DDRB 
      #define    I2C_read    PINB 
      #define    I2C_set        PORTB 

      #define Set_SDA        cbi(I2C,sda) 
      #define Cls_SDA        sbi(I2C,sda) 
      #define Set_SCL        cbi(I2C,scl) 
      #define Cls_SCL        sbi(I2C,scl) 
      #define SDA_High         bit_is_set(I2C_read,sda) 

      //function declaration 
      void I2C_Delay(void); 
      void I2C_Start(void); 
      void I2C_Stop(void); 
      unsigned char I2C_Write(unsigned char wb); 
      unsigned char I2C_Read(unsigned char bEnd); 

      //***************************************************** 
      //delay 100us 
      //***************************************************** 
      void I2C_Delay(void) 
      { 
          _delay_us(100); 
      } 

      //***************************************************** 
      //i2c init 
      //***************************************************** 
      void I2C_init(void) 
      { 

      //DDR    PORT     
      //0    0    in,high 
      //0    1    in,r 
      //1    0    out=0 
      //1    1    out=1 

          cbi(I2C_set,sda);        //sda=1 
          cbi(I2C,sda);            //sda in 
          cbi(I2C_set,scl);        //scl=1; 
          cbi(I2C,scl);            //scl in 
      } 

      //***************************************************** 
      //i2c start 
      //***************************************************** 
      void I2C_Start(void) 
      { 
           Cls_SCL; 
           I2C_Delay(); 
           Set_SDA; 
           I2C_Delay(); 

           Set_SCL; 
           I2C_Delay(); 
           Cls_SDA; 
           I2C_Delay(); 

           Cls_SCL; 
           I2C_Delay();          
      } 

      //***************************************************** 
      //i2c stop 
      //***************************************************** 
      void I2C_Stop(void) 
      { 
           Cls_SDA; 
           I2C_Delay(); 
            
           Set_SCL; 
           I2C_Delay(); 
           Set_SDA; 
           I2C_Delay(); 

           Set_SCL; 
           I2C_Delay(); 
      } 

      //***************************************************** 
      //I2C_Write  
      //***************************************************** 
      unsigned char I2C_Write(unsigned char wb) 
      { 
          unsigned char i,ack=0; 
           
          for(i=0;i<8;i++) 
          { 
               if( wb&0x80 ) Set_SDA; 
               else          Cls_SDA; 
               wb=wb<<1; 
               I2C_Delay(); 
                
               Set_SCL; 
               I2C_Delay(); 
               Cls_SCL; 
               if(i!=7)    I2C_Delay(); 
          } 
           
          Set_SDA;        //release sda line 
          I2C_Delay(); 
          Set_SCL; 
          I2C_Delay(); 
           
          if( SDA_High )    ack=1;    //ack error 

          Cls_SCL; 
          I2C_Delay(); 
           
          return ack; 
      } 

      //***************************************************** 
      //I2C_Read 
      //***************************************************** 
      unsigned char I2C_Read(unsigned char bEnd) 
      { 
          unsigned char i,mb; 
           
          Set_SDA;    //release sda line 
          mb=0; 
          for(i=0;i<8;i++) 
          { 
              mb=mb<<1; 
               
              I2C_Delay(); 
              Set_SCL; 
              I2C_Delay(); 
              if( SDA_High ) mb++; 
              I2C_Delay(); 
              Cls_SCL; 
              if(i!=7)        I2C_Delay(); 
          } 
          if( bEnd )      Set_SDA;        //end read 
          else            Cls_SDA;        //ack 
          I2C_Delay(); 
           
          Set_SCL; 
          I2C_Delay(); 
          Cls_SCL; 
          I2C_Delay(); 
          Set_SDA; 
           
          return mb; 

      }