i2c.c

C code for using 8051 to control philiphs I2C FM tuner (use sdcc compiler)

#include <at89x52.h>
#include "i2c.h"
/* Generate the start condition */
void I2C_Start()
{
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
	I2C_SDA_SET;
	I2C_SCL_SET;
	I2C_NOP();
	I2C_SDA_CLR;
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
}
 
/* Generate the stop condition */
void I2C_Stop()
{
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
	I2C_SDA_CLR;
	I2C_NOP();
	I2C_SCL_SET;
	I2C_NOP();
	I2C_SDA_SET;
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
}
 
/* Master send a byte to the slave device */
void I2C_Send_Byte(unsigned char byte)
{
	unsigned char mask;

	/* Send the byte from MSB to LSB */
	for (mask = 0x80 ; mask > 0 ; mask = mask >> 1 )
	{
		I2C_SCL_CLR;

		if (byte & mask)
			I2C_SDA_SET;
		else
			I2C_SDA_CLR;
 
		I2C_NOP();
		I2C_SCL_SET;
		I2C_NOP();
		I2C_SCL_CLR;
		I2C_NOP();
	}
 
	/* Check the Acknowledge from slave device */
	I2C_SDA_SET;
	I2C_NOP();
	I2C_SCL_SET;
	I2C_NOP();
	while(I2C_SDA_GET == I2C_NO_ACK);
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
	I2C_SDA_SET;	// Release the Bus
	I2C_NOP();
}
 
/* Master send the slave address */
void I2C_Send_Addr(unsigned char addr, unsigned char dir)
{
	I2C_Send_Byte(addr + dir);
}
/* Master get a byte from the slave device */
unsigned char I2C_Get_Byte(unsigned char last)
{
	unsigned char mask;
	unsigned char retVal;
 
	retVal 	= 0;	/* initial the return value */
 
	for (mask = 0x80 ; mask != 0 ; mask = mask >> 1)
	{
		I2C_NOP();
		I2C_SCL_SET;
		I2C_NOP();
		if(I2C_SDA_GET)
			retVal = retVal | mask;
		I2C_NOP();
		I2C_SCL_CLR;
		I2C_NOP();
	}
 	if ( last == 1)
		I2C_SDA_SET; /* No Acknowledge */
	else
		I2C_SDA_CLR; /* Acknowledge */
	
	I2C_NOP();
	I2C_SCL_SET;
	I2C_NOP();
	I2C_SCL_CLR;
	I2C_NOP();
	I2C_SDA_SET;	// Release the bus
	I2C_NOP();

	return retVal;
}