i2c_virsual.c

基于51单片机的IIC通信规则,包含了EEPROM的写入以及读取.

/*********************************************************************************
****Micocontroller:  AT89C51 at 12MHz     ** * * * **       *      ********    **      
************Device:  24aa512, 2           **       **      * *     **    **    **
*Programming Model:  Virtual I2C          ** * *   **     *   *     ***  ********    
************Author:  ***                  **       **    * *** *     *** **    **
**************Date:  2006.11.08           **       ** * *       *******  **    **   
*********************************************************************************/
 #include<string.h>
          #include<at89x51.h>
          #include<intrins.h>
          #define DELAY_TIME 60 /*经实验，不要小于50！否则可能造成时序混乱*/
          #define TRUE 1
          #define FALSE 0
		  #define FLASH_PAGE  7 /*存储器页面大小*/
          sbit SCL=P1^7;/*假设由P1.7和P1.6控制*/
          sbit SDA=P1^6;
      /********** Function Definition　函数定义 ************/
          void DELAY(unsigned int t) /*延时函数*/
          {
              while(t!=0)
                  t--;
          }
          void I2C_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 I2C_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)   /* SEND ACK */
          {
              /*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 WriteI2CByte(char b)reentrant
          {
              /*向I2C总线写一个字节*/
              char i;
              for(i=0;i<8;i++)
                  if((b<<i)&0x80)
                      SEND_1();
                  else
                      SEND_0();
          }
      
          char ReadI2CByte(void)reentrant
          {
              /*从I2C总线读一个字节*/
              char 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;   /*psw for user flag*/
                  DELAY(10);
                  SCL=0;
                  if(F0==1)
                      {
                          b=b<<1;
                          b=b|0x01;
                      }
                  else
                      b=b<<1;
              }
              return b;
          }

      /**********以下为读写24aa512的函数**********/
      void Write_One_Byte(char id, char addrh,char addrl, char thedata)
      {
                bit acktemp=1;
                /*write a byte to mem*/
                I2C_Start();
                WriteI2CByte(id);
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrh);/*address high byte*/
                acktemp=Check_Acknowledge(); 
                WriteI2CByte(addrl);/*address low  byte*/
                acktemp=Check_Acknowledge();
                WriteI2CByte(thedata);/*thedata*/
                acktemp=Check_Acknowledge();
                I2C_Stop();
      }
      void Write_A_Page( char id, char *buffer,char addrh,char addrl) /*page data number is different*/
      {
                bit acktemp=1;
                bit wrtmp;
                int i;
                /*write a page to at24c02*/
                I2C_Start();
                WriteI2CByte(id);
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrh);/*address high byte*/
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrl);/*address low  byte*/
                acktemp=Check_Acknowledge();
                for(i=0;i<FLASH_PAGE;i++)
                {
                  WriteI2CByte(buffer[i]);
                  if(!Check_Acknowledge())
                      {
                          I2C_Stop();
                      }
                 }

                I2C_Stop();
      

      }
      char Read_One_Byte(char id ,char addrh,char addrl)
      {         bit acktemp=1;
                char mydata;
                 /*read a byte from mem*/
                I2C_Start();
                WriteI2CByte(id);
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrh);/*address high byte*/
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrl);/*address low  byte*/
                acktemp=Check_Acknowledge();
                I2C_Start();
                WriteI2CByte(id+1);
                acktemp=Check_Acknowledge();

                mydata=ReadI2CByte();
                acktemp=Check_Acknowledge();
                return mydata;
                I2C_Stop();
      }
      void Read_N_Bytes(char id ,char *buffer,char n,char addrh,char addrl)
      {
                bit acktemp=1;
                int i=0;
                 /*read 8 bytes from mem*/
                I2C_Start();
                WriteI2CByte(id);
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrh);/*address high byte*/
                acktemp=Check_Acknowledge();
                WriteI2CByte(addrl);/*address low  byte*/
                acktemp=Check_Acknowledge();
                I2C_Start();
                WriteI2CByte(id+1);
                acktemp=Check_Acknowledge();
      

                for(i=0;i<n;i++)
                {
                      buffer[i]=ReadI2CByte();
                      if(i!=n-1)
                          SEND_0();    /*发送应答*/
                      else
                          SEND_1();    /*发送非应答*/
                }
         I2C_Stop();
      }

      void main()
      {
                int i;
                char mybyte;
                char myarray[8];
                char myarray2[8];
                char rdarray1[16];
                char rdarray2[16];
               
                for(i=0;i<8;i++)
                {
                      myarray[i]=i;
                      myarray2[i]=i*16;    
					  rdarray1[i]=0;    /*clr*/
					  rdarray1[i+8]=0;  /*clr*/
					   rdarray2[i]=0;    /*clr*/
					  rdarray2[i+8]=0;  /*clr*/
                }
                Write_One_Byte(0xa0,0x00,0x20,0x28);
                Write_A_Page( 0xa0, myarray,0x00,0x10);
                Write_A_Page(0xa0, myarray2,0x00,0x18);
                mybyte=Read_One_Byte(0xa0,0x00,0x20);
                Read_N_Bytes(0xa0,rdarray1,6,0x00,0x10);

               // Write_A_Page(0xa2, myarray, 0x00,0x10);  /*the second 24aa512*/
               // Write_A_Page(0xa2, myarray2,0x00,0x18);
                 Read_N_Bytes(0xa2,rdarray2,10,0x00,0x17);

				while (1)
				{
			          for (i=0;i<6;i++)
				      {
    			      P2=rdarray1[i];
					  DELAY(1000);
				      }
                      
					   for (i=0;i<10;i++)
				      {
    			      P3=rdarray2[i];
					 
					  DELAY(1000);
				      }



				}      



      }