ARM7 Getting Started 11, IIC Communication

Main program:

/*******************************************************************************
*File: Main.C
*Function: Use hardware I2C to operate EEPROM, and use interrupt mode to operate
******************************************************************************/
#include "config.h"
#define CAT24WC02 0xA0 /*Define device address*/
#define LED1CON 0x00000400 /*P0.10 pin controls LED1, low level lights up*/
/*The following are the variables required for I2C operation, and these variables must be set before calling the I2C subroutine*/
volatile uint8 I2C_sla; //Slave addressvolatile
uint8 I2C_suba; //Sub addressvolatile
uint8 *I2C_buf; //Data buffer pointer (will be changed during read operation)
volatile uint8 I2C_num; //Number of operation datavolatile
uint8 I2C_end; //Operation end flag, 1 indicates the operation is over, 0xFF indicates the operation failed
volatile uint8 I2C_suba_en; //Sub-address enable control, set to 1 for read operation and 2 for write operation

/*******************************************************************************
*Name: IRQ_I2C()
*Function: I2C interrupt, perform corresponding operations by judging the I2C status word
********************************************************************/
void __irq IRQ_I2C(void)
{ uint8 sta;
  sta=I2STAT; //Read out the I2C status wordswitch
  (sta)
  { case 0x08: //The start condition has been sentif
    (1==I2C_suba_en)I2DAT=I2C_sla&0xFE; //When specifying the sub-address to read, write the address firstelse
    I2DAT=I2C_sla; //Otherwise, send the slave address directlyI2CONCLR
    =0x28; //SI=0
    break;
    
    case 0x10:
    I2DAT=I2C_sla; //After restarting the bus, send the slave addressI2CONCLR
    =0x28; //SI=0
    break;
    case 0x18: //SLA+W has been sent, and the response has been received
    if(0==I2C_suba_en) //No sub-address, then send data directly
    { if(I2C_num>0)
    { I2DAT=*I2C_buf++;
      I2CONCLR=0x28;
      I2C_num--;
    }
    else
    { I2CONSET=0x10; //No data to send, end the bus
      I2CONCLR=0x28;
      I2C_end=1; //Set the bus operation end flag
    }
    break;
    }
    if(1==I2C_suba_en) //Send sub-address
    { I2DAT=I2C_suba;
      I2CONCLR=0x28;
    }
    if(2==I2C_suba_en) //Send sub-address
    { I2DAT=I2C_suba;
      I2CONCLR=0x28;
      I2C_suba_en=0; //Subaddress processed
    }
    break;
  case 0x28: //I2C data sent, and response received
    if(0==I2C_suba_en) //No subaddress, send data directly
    { if(I2C_num>0)
    { I2DAT=*I2C_buf++;
    I2CONCLR=0x28;
    I2C_num--;
    }
    else
    { I2CONSET=0x10; //No data sent, end bus
      I2CONCLR=0x28;
      I2C_end=1;
     }
    break;
    }
    if(1==I2C_suba_en) //If the address is specified, restart the bus
    { I2CONSET=0x20;
      I2CONCLR=0x18;
      I2C_suba_en=0; //Subaddress processed
    }
    break; 
   
case 0x20:
case 0x30:
case 0x38:
  I2CONCLR=0x28; //The bus enters the non-addressable slave mode
  I2C_end=0xFF; //Bus error, set the flag
  break;
case 0x40: //SLA+R has been sent and the response has been received
  if(1==I2C_num) //The last byte, send a non-response signal after receiving the data
  { I2CONCLR=0x2C; //AA=0, generate a non-response after receiving the data
  }
  else //Receive data and send a response signal
  { I2CONSET=0x04; //AA=1, generate a response after receiving the data
    I2CONCLR=0x28;
  }
  break;
case 0x50:
  *I2C_buf++=I2DAT; //Read data
  I2C_num--;
  if(1==I2C_num)
  { I2CONCLR=0x2C;  
  }
  else
  {I2CONSET=0x04;
   I2CONCLR=0x28;
  }
  break;
case 0x58:
  *I2C_buf++=I2DAT; //Read the last byte of data
  I2CONSET=0x10; //End the bus
  I2CONCLR=0x28;
  I2C_end=1;
  break;
case 0x48:
  I2CONCLR=0x28; //The bus enters the non-addressable slave mode
  I2C_end=0xFF;
  break;
}
VICVectAddr=0x00; //End of interrupt processing
}  

/*******************************************************************************
*Name: ISendStr()
*Function: Use hardware I2C to send data
****************************************************************************/
uint8 ISendStr(void)
{ I2C_end=0;

  I2CONCLR=0x2C;
  I2CONSET=0x40; //Enable I2C
  I2CONSET=0x64; //Set as host and start the buswhile
  
  (0==I2C_end);
  if(1==I2C_end)return(1);
  else return(0);
}
/*******************************************************************************
*Name: IRcvStr()
*Function: Use hardware I2C to read data
*******************************************************************************/
uint8 IRcvStr(void)
{ if(0==I2C_num)return(0);
  I2C_end=0;
  I2CONCLR=0x2C;
  I2CONSET=0x40; //Enable I2C
  I2CONSET=0x64; //Set as host and start the buswhile
  (0==I2C_end);
  if(1==I2C_end)return(1);
  else return(0);
}
/*******************************************************************************
*Name: I2C_Init()
*Function: I2C initialization, including initialization of its interrupt as vector IRQ interrupt
*******************************************************************************/
void I2C_Init(void)
{ /*Set I2C clock to 100kHz*/
  I2SCLH=I2SCLL=14; //Crystal oscillator is 11.0592MHz, Fpclk=2.7648MHz
  /*Set I2C interrupt enable*/
  VICIntSelect=0x00000000; //Set all channels to IRQ interrupt
  VICVectCntl0=0x29; //I2C channel is assigned to IRQ Slot0, which has the highest priority
  VICVectAddr0=(int)IRQ_I2C; //Set I2C interrupt vector address
  VICIntEnable=0x0200; //Enable I2C interrupt
  
}
/****************************************************************************
*Name: DelayNS()
*Function: Long software delay
************************************************************************/
void DelayNS(uint32 dly)
{ uint32 i;
  for(;dly>0;dly--)
    for(i=0;i<50000;i++);
}
/***********************************************************************************
*Name: WrEepromErr()
*Function: Read and write E2PROM error alarm, i.e. flashing LED1
*******************************************************************************/
void WrEepromErr(void)
{ while(1)
 { IO0SET=LED1CON;
  DelayNS(50);
  IO0CLR=LED1CON;
  DelayNS(50);
 }
}
/*******************************************************************************
*Name: main()
*Function: Write 10 bytes of data to E2PROM, and then read it out to determine whether it is written correctly
******************************************************************************/
int main(void)
{ uint8 i;
   uint8 data_buf[30];
   PINSEL0=0x00000050; //Set the I/O port working mode to use I2C
   PINSEL1=0x00000000;
   IO0DIR=LED1CON; //Set LED1 control port to output and other I/O to input
   I2C_Init(); //I2C initialization
   for (i=0;i<10;i++)data_buf[i]=i+'0';
   I2C_sla=CAT24WC02;
   I2C_suba=0x00;
   I2C_suba_en=2;
   I2C_buf=data_buf;
   I2C_num=10;
   ISendStr(); //Write 10 bytes of data at 0x00 address
   DelayNS(1); //Wait for the write cycle to end
   for(i=0;i<10;i++)data_buf[i]=0;
   I2C_sla=CAT24WC02+1;
   I2C_suba=0x00;
   I2C_suba_en=1;
   I2C_buf=data_buf;
   I2C_num=10;
   IRcvStr(); //Read 10 bytes of data at 0x00 address
   /*Check the read data, if incorrect, flash the LED alarm*/
   for(i=0;i<10;i++)
   { if(data_buf[i]!=(i+'0'))WrEepromErr();
   }
   IO0CLR=LED1CON; //Light up LED1
   while(1);
}