iic.c

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//-----------------------------------------------------------------------------
// iic.c
//-----------------------------------------------------------------------------
//
//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------
#include <reg52.h>
#include <intrins.h>
#include "cpu/cpu.h"
#include "misc/general.h"
//-----------------------------------------------------------------------------
// Function Prototypes
//-----------------------------------------------------------------------------
void i2c_Start      ( void );
void i2c_Stop       ( void );
char i2c_Read_Byte  ( bit ack );
bit  i2c_Write_Byte ( char c );
//------------------------------------------------------------------------------------
// i2c Start Routine
//------------------------------------------------------------------------------------
void i2c_Start (void)
{
    i2c_SDA = HIGH;
    i2c_SCL = HIGH;
	_nop_ ();
    i2c_SDA = LOW;
	_nop_ ();	_nop_ ();
    i2c_SCL = LOW;
}
//------------------------------------------------------------------------------------
// i2c Stop Routine
//------------------------------------------------------------------------------------
void i2c_Stop (void)
{
    i2c_SDA = LOW;
    i2c_SCL = HIGH;
	_nop_ ();
    i2c_SDA = HIGH;
}
//------------------------------------------------------------------------------------
// i2c Write Byte Routine
//------------------------------------------------------------------------------------
bit i2c_Write_Byte (char c)
{
	char i;	 bit ack;

	for ( i = 8; i > 0; i-- )
	{
		if ( c & MSB )
		    i2c_SDA = HIGH;
    	else
			i2c_SDA = LOW;
	    i2c_SCL = HIGH;
		_nop_ ();
		c <<= 1;
	    i2c_SCL = LOW;
	}
    i2c_SDA = HIGH;
    i2c_SCL = HIGH;

	_nop_ ();
	ack = I2C_ACK;
	if ( i2c_SDA == HIGH ) ack = I2C_NACK;
	_nop_ ();	_nop_ ();
	i2c_SCL = LOW;
	_nop_ ();	_nop_ ();
	return ack;
}
//------------------------------------------------------------------------------------
// i2c Read Byte Routine
//------------------------------------------------------------------------------------
char i2c_Read_Byte (bit ack)
{
	char i, c = 0;

    i2c_SDA = HIGH;
	for ( i = 8; i > 0; i-- )
	{
	    i2c_SCL = HIGH;
		_nop_ ();
		c <<= 1;
		if ( i2c_SDA == HIGH ) c |= LSB;
	    i2c_SCL = LOW;
	}
	if ( ack == I2C_ACK ) i2c_SDA = LOW;
	i2c_SCL = HIGH;
	_nop_ ();
    i2c_SCL = LOW;
	return c;
}