i2c.c

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// ---------------------- Software I2C bus implementation ----------------------
/*  FileName: i2c.c
	Version : 0.1
	Last Updated: 2007-3-2
	Description:
	This library contains the necessary functions for Simulating SPI bus.
	Program Coder: Seeseawe
*/

// Start an I2C communication
void I2C_Start(void)
{
	I2C_SDA = 1;
	I2C_SCL = 1;
	//delay4us();
	I2C_SDA = 0;
	//delay4us();
	I2C_SCL = 0;
}

// Stop an I2C Communication
void I2C_Stop(void)
{
	I2C_SDA = 0;
	I2C_SCL = 1;
	//delay4us();
	I2C_SDA = 1;
	//delay4us();
}

// Send a byte to I2C Bus
void I2C_SendByte(uint8 dByte)
{
	uint8 i;
	for (i = 0; i < 8; i++)
	{
		I2C_SDA = (dByte<<i) & 0x80;
		I2C_SCL = 1;
		//delay4us();
		I2C_SCL = 0;
	}
	// Release the bus and clock out ACK signal from Slave
	I2C_SDA = 1;
	I2C_SCL = 1;
	//delay4us();
	/*
	if (I2C_SDA == 1)
		ACK = 0;
	else
		ACK = 1;
	*/
	I2C_SCL = 0;
}

// Read a byte from the slave
uint8 I2C_ReadByte(void)
{
	uint8 dByte;
	uint8 i;
	for ( i = 0; i < 8; i++ )
	{
		I2C_SDA = 1;			// Release I2C_SDA
		I2C_SCL = 1;			// Release I2C_SCL
		while(I2C_SCL == 0);	// Synchronize clock
		delay4us();
		dByte <<= 1;		// Shift left the result		
		if (I2C_SDA)
		dByte |= 0x01;		// Set actual I2C_SDA state to LSB		
		I2C_SCL = 0;			// Force a clock cycle
		delay4us();
	}
	return dByte;
}

// Send an ACK or NACK signal to the slave
void I2C_SendAck(bit ACK)
{
	I2C_SDA = ACK;
	I2C_SCL = 1;
	while(I2C_SCL == 0);   // Synchronize clock
	delay4us();
	I2C_SCL = 0;
}