uart2iic.c

USB I2C 8051 control source code

//
//        www.dainau.com
//

#include <AT892051.H>
#include "intrins.h"     

#define IIC_init  0xC1
#define IIC_start 0xC2
#define IIC_send  0xC3
#define IIC_read  0xC4
#define IIC_stop  0xC5
#define IIC_ack   0xC6
#define IIC_nack  0xC7

sbit ISDA = P1^0;
sbit ISCL = P1^1;
sbit LED = P1^2;

unsigned char buffcount;
unsigned char buffer[64];

void init(void);
void delay(int d);
void waitRI(int t);
char sendbyte (char c);  
bit I2cSentByte(SBUF);
unsigned char I2cReceiveByte(void);


main()
{ 
  int i;	
  unsigned char iicmd;

  init();

  while(1){
    waitRI(0);
    iicmd=SBUF;
    RI=0;
    switch (iicmd) {
           case IIC_init:
		        ISDA = 1;
		        ISCL = 1;
 				break;
           case IIC_start:
		        ISDA = 0;
				delay(5);
		        ISCL = 0;
 				break;
           case IIC_send:
			    waitRI(0);
                iicmd=SBUF;
                RI=0;
				iicmd=I2cSentByte(iicmd);   //out IIc 
				sendbyte(iicmd);   //response ack to PC
 				break;
           case IIC_read:
		        iicmd=sendbyte(I2cReceiveByte());
				sendbyte(iicmd);   //response ack to PC
 				break;
           case IIC_stop:
		        ISDA = 0;
				delay(5);
		        ISCL = 1;
				delay(5);
		        ISDA = 1;
 				break;
           case IIC_ack:
		        ISDA = 0;
				delay(1);
		        ISCL = 1;
				delay(1);
		        ISCL = 0;
				delay(1);
		        ISDA = 1;
 				break;
           case IIC_nack:
		        ISCL = 1;
				delay(1);
		        ISCL = 0;
 				break;
           default:
 				break;
    }
  }
}

void waitRI(int t)
{
  if(t==0) 
    while(RI==0){
      LED=!LED;
    }
  else
    while(--t>0){
       if(RI==1) break;
       LED=!LED;
  }
}

void init(void)
{
  
  PCON = 0x80;
  TMOD = 0x21;
  TH1  = 0xFF;
  TCON = 0x55;
  SCON = 0x50;
  
  EA=1;
  ES=0;
  TI=1;

}

void uartint (void) interrupt 4
{

  if(TI==1){ 
   if(RI==1){
     buffer[buffcount++]=SBUF;
	 RI=0; 
   }
  }
  
}

void delay(int d)
{
  int i;
  for(i=0;i<d;i++);
}

char sendbyte (char c)  
{

  while (!(SCON & 0x02));       /* while (!TI); */
  SCON &= 0xFD;                 /* TI = 0 */
  return (SBUF = c);
}

bit I2cSentByte(unsigned char bytedata)
{
    unsigned char i;
    bit ack;

    for(i=0; i<8; i++)
    {
       bytedata=_crol_(bytedata,1);     
       if (bytedata & 0x01)
          ISDA=1; 
       else
          ISDA=0;       

       ISCL=1;
	   delay(1);
       ISCL=0;
    }
  
    ISDA=1;
    delay(1);
    ISCL=1;
    ack=ISDA;
    delay(1);
    ISCL=0;
    return ack;
}

unsigned char I2cReceiveByte(void)
{ 
    unsigned char i;
    unsigned char bytedata=0;

    // Receive byte (MSB first)
    for(i=0; i<8; i++)
    {  
       ISCL=1;
       delay(1);
          
       bytedata <<= 1;
       if ( ISDA )  bytedata |= 0x01;
     
       ISCL=0;
       delay(1);
    }
    return bytedata;  
}