在51上用p1口模拟i2c.txt

I2C总集--24C256读写程序,X5043读写程序,24C02读写程序

在51上用P1口模拟I2C

      作者：佚名
      下面是用普通C51实现的I2C基本电平模拟函数和通用函数。 

      /*  电平模拟函数和基本读写函数 
          void IIC_Start(void); 
          void IIC_Stop(void); 
          void SEND_0(void); 
          void SEND_1(void); 
          bit Check_Acknowledge(void); 
          void Write_Byte(uchar b)reentrant; 
          bit Write_N_Bytes(uchar *buffer,uchar n)reentrant; 
          bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer); 
          uchar Read_Byte(void)reentrant; 
      */ 

          #include<string.h> 
          #include<reg52.h> 
          #include<intrins.h> 
          #include"aiic_51.h" 

          sbit SCL=P1^6; 
          sbit SDA=P1^7; 

          void DELAY(uint t) 
          { 
              while(t!=0) 
                  t--; 
          } 

          void IIC_Start(void) 
          { 
              //启动I2C总线的函数，当SCL为高电平时使SDA产生一个负跳变 
              SDA=1; 
              SCL=1; 
              DELAY(DELAY_TIME); 
              SDA=0; 
              DELAY(DELAY_TIME); 
              SCL=0; 
              DELAY(DELAY_TIME); 
          } 

          void IIC_Stop(void) 
          { 
              //终止I2C总线，当SCL为高电平时使SDA产生一个正跳变 
              SDA=0; 
              SCL=1; 
              DELAY(DELAY_TIME); 
              SDA=1; 
              DELAY(DELAY_TIME); 
              SCL=0; 
              DELAY(DELAY_TIME); 
          } 

          void SEND_0(void) 
          { 
              //发送0，在SCL为高电平时使SDA信号为低 
              SDA=0; 
              SCL=1; 
              DELAY(DELAY_TIME); 
              SCL=0; 
              DELAY(DELAY_TIME); 
          } 

          void SEND_1(void) 
          { 
              //发送1，在SCL为高电平时使SDA信号为高 
              SDA=1; 
              SCL=1; 
              DELAY(DELAY_TIME); 
              SCL=0; 
              DELAY(DELAY_TIME); 
          } 

          bit Check_Acknowledge(void) 
          { 
              //发送完一个字节后检验设备的应答信号 
              SDA=1; 
              SCL=1; 
              DELAY(DELAY_TIME/2); 
              F0=SDA; 
              DELAY(DELAY_TIME/2); 
              SCL=0; 
              DELAY(DELAY_TIME); 
              if(F0==1) 
                  return FALSE; 
              return TRUE; 
          } 

          void Write_Byte(uchar b)reentrant 
          { 
              //向IIC总线写一个字节 
              uchar i; 
              for(i=0;i<8;i++) 
                  if((b<<i)&0x80) 
                      SEND_1(); 
                  else 
                      SEND_0(); 
          } 

          bit Write_N_Bytes(uchar *buffer,uchar n)reentrant 
          { 
              //向I2C总线写n个字节 
              uchar i; 
              IIC_Start(); 

              for(i=0;i<n;i++) 
              { 
                  Write_Byte(buffer[i]); 
                  if(!Check_Acknowledge()) 
                      { 
                          IIC_Stop(); 
                          return(i==n); 
                      } 
              } 

              IIC_Stop(); 
              return TRUE; 
          } 

          uchar Read_Byte(void)reentrant 
          { 
              //从I2C总线读一个字节 
              uchar b=0,i; 
              for(i=0;i<8;i++) 
              { 
                  SDA=1;    //释放总线 
                  SCL=1;    //接受数据 
                  DELAY(10); 
                  F0=SDA; 
                  DELAY(10); 
                  SCL=0; 
                  if(F0==1) 
                      { 
                          b=b<<1; 
                          b=b|0x01; 
                      } 
                  else 
                      b=b<<1; 
              } 
              return b; 
          } 

          bit Read_N_Bytes(uchar SlaveAdr,uchar n,uchar *buffer) 
          { 
              //从I2C总线读n个字节 
              uchar i; 
              IIC_Start(); 
              Write_Byte(SlaveAdr);        //向总线发送接收器地址 
              if(!Check_Acknowledge())     //等待接收器应答信号 
                  return FALSE; 
              for(i=0;i<n;i++) 
                  { 
                      buffer[i]=Read_Byte(); 
                      if(i!=n) 
                          SEND_0();    //发送应答 
                      else 
                          SEND_1();    //发送非应答 
                  } 
              IIC_Stop(); 
              return TRUE; 
          }