soft_i2c.c

/*
 * File Name: soft_i2c.c
 * Author: Siddharth Chandrasekaran
 * Website	: http://embedjournnal.com/
 * Created on July 27, 2012, 12:12 PM
*/

#include "soft_i2c.h"
#include "delay.h"

unsigned char i2cReadByte(void)
{
   unsigned char inByte, n;
   i2cHighSda();
   for (n=0; n<8; n++)
   {
      i2cHighScl();

      if (SDA_PIN)
         inByte = (inByte << 1) | 0x01; // msbit first
      else
         inByte = inByte << 1;
      i2cLowScl();
   }
   return(inByte);
}

void i2cWriteByte(unsigned char outByte)
{
   unsigned char n;
   for(n=0; n<8; n++)
   {
      if(outByte&0x80)
         i2cHighSda();
      else
         i2cLowSda();
      i2cHighScl();
      i2cLowScl();
      outByte = outByte << 1;
   }
   i2cHighSda();
}

void i2cNack(void)
{
   i2cHighScl();
   i2cLowScl();		// bring data high and clock
}

void i2cAck(void)
{
   i2cLowSda();	
   i2cHighScl();
   i2cLowScl();
   i2cHighSda();		// bring data low and clock
}


void i2c_start(void)
{
   i2cLowScl();
   i2cHighSda();
   i2cHighScl();	
   i2cLowSda();
   i2cLowScl();		// bring SDA low while SCL is high
}

void i2cStop(void)
{
   i2cLowScl();
   i2cLowSda();
   i2cHighScl();
   i2cHighSda();		// bring SDA high while SCL is high
}

void i2cHighSda(void)
{
   SDA_DIR = 1;		// bring SDA to high impedance
   delayUs(5);
}

void i2cLowSda(void)
{
   SDA_PIN = 0;
   SDA_DIR = 0;		// output a logic zero
   delayUs(5);
}

void i2cHighScl(void)
{
   SCL_DIR = 1;		// bring SCL to high impedance
   delayUs(5);
}

void i2cLowScl(void)
{
   SCL_PIN = 0;		
   SCL_DIR = 0;
   delayUs(5);
}