i2c.c

开发环境ADSP6++,EBF_561开发板所有源代码

#include "system.h"


#define I2C_CLK		0x4000		// PF14
#define I2C_DATA	0x8000		// PF15

//------------------------------------------------------------------------------
// I2C Peripheral Function Prototypes
//------------------------------------------------------------------------------
void Init(void);									//  Initialize I2C port
void Start(void);									//  Sends I2C Start Trasfer
void Stop(void);									//  Sends I2C Stop Trasfer
bool Write(unsigned char data_out);				//  Writes data over the I2C bus
bool Read(unsigned char *data_in, bool send_ack);	// Reads data from the I2C bus
void SetSCLK(bool state);						//  Set SCLK to <state>
void SetSDATA(bool state);						//  Set SDATA to <state>
bool GetSDATA();								//  Get SDATA state

//------------------------------------------------------------------------------


//------------------------------------------------------------------------------
// I2C Peripheral Variables
//------------------------------------------------------------------------------
unsigned char IdentAddr = 0x00;
unsigned int I2C_Delay = 0x00000000;

//------------------------------------------------------------------------------


//------------------------------------------------------------------------------
// Procedure:	I2C_Init
// Inputs:		identaddr
// Outputs:		bool
// Description:	Initialize I2C and setup Slave Ident Addr. then check the ident
//				for response and returns true if ok.
//------------------------------------------------------------------------------
bool I2C_Init(unsigned char identaddr)
{
	bool ret;

	// Calculate Delay NEED FIX!!!
	I2C_Delay = ((*pPLL_CTL & 0x7e00) >> 9); //jiapeng change 9 to 8;
	if ((*pPLL_CTL & 0x0001) == 0x0001)
		I2C_Delay /= 2;
        //jiapeng adds it.   
	I2C_Delay *= 2;

	IdentAddr = identaddr;

	Init();								// Initialize I2C port
	Start();								// Check Slave Ident Addr
	ret = Write(IdentAddr);
	Stop();

	return ret;							// Return true if Ident Addr. Ok
}


//------------------------------------------------------------------------------
// Procedure:	I2C_Write
// Inputs:		data out, address
// Outputs:		bool
// Description:	Writes a byte to the given address and return status.
//------------------------------------------------------------------------------
bool I2C_Write(unsigned char data_out, unsigned char address)
{
	Start();							// Send start signal
	if (!Write(IdentAddr))			// Send identifier I2C address
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	if (!Write(address))				// Send address to device
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	if (!Write(data_out))				// Send byte to device
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	Stop();							// Send I2C Stop Transfer

	return true;
}



//------------------------------------------------------------------------------
// Procedure:	I2C_Read
// Inputs:		*data_in, address
// Outputs:		bool
// Description:	Reads a byte from the given address and return status.
//------------------------------------------------------------------------------
bool I2C_Read(unsigned char *data_in, unsigned char address)
{
	Start();							// Send start signal
	if (!Write(IdentAddr))			// Send identifer I2C address
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	if (!Write(address))				// Send address to device
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	Start();							// Send I2C Start Transer
	if (!Write(IdentAddr+1))			// Send identifer I2C address
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	if (!Read(data_in, false))			// Read byte
	{
		Stop();						// Send I2C Stop Transfer
		return false;
	}
	Stop();							// Send I2C Stop Transfer

	return true;
}


//------------------------------------------------------------------------------
// I2C Functions - Master
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
// 	Routine:	Init
//	Inputs:	none
//	Outputs:	none
//	Purpose:	Initialize I2C for the ADu812C
//------------------------------------------------------------------------------
inline void Init(void)
{
	*pFIO0_DIR |= I2C_CLK;		// Set SCLK as output and SDATA as input/high
	*pFIO0_POLAR &= ~I2C_DATA;	// Enable Active Hight
	*pFIO0_EDGE &= ~I2C_DATA;	// Enable Level Sensitivity
	*pFIO0_INEN |= I2C_DATA;		// Enable SDATA Input Buffer
	SetSDATA(1);				// Set SDATA as input/high
	SetSCLK(1);					// Set SCLK high
}


//------------------------------------------------------------------------------
// 	Routine:	Start
//	Inputs:		none
//	Outputs:	none
//	Purpose:	Sends I2C Start Trasfer - "S"
//------------------------------------------------------------------------------
inline void Start(void)
{
	//11182003 - Following line has been added! (Fixed thanks to Andrew Seddon).
	//			Shouldn't Stop() be setting SCLK high?
	SetSCLK(1);		// Set SCLK high
	SetSDATA(0);	// Set SDATA output/low
	SetSCLK(0);		// Set SCLK low
}


//------------------------------------------------------------------------------
// 	Routine:	Stop
//	Inputs:	none
//	Outputs:	none
//	Purpose:	Sends I2C Stop Trasfer - "P"
//------------------------------------------------------------------------------
inline void Stop(void)
{
	SetSDATA(0);	// Set SDATA output/low
	SetSCLK(1);		// Set SCLK high
	SetSDATA(1);	// Set SDATA as input/high
}


//------------------------------------------------------------------------------
// 	Routine:	Write
//	Inputs:	data_out
//	Outputs:	bool
//	Purpose:	Writes data over the I2C bus and return status.
//------------------------------------------------------------------------------
inline bool Write(unsigned char data_out)
{
	unsigned char index;

	// An I2C output byte is bits 7-0 (MSB to LSB). Shift one bit at a time to
	// the SDATA output, and then clock the data to the I2C Slave device.

	// Send 8 bits out the port	
	for (index = 0; index < 8; index++)
	{
		// Output the data bit to the device
		SetSDATA(((data_out & 0x80) ? 1 : 0));

		data_out <<= 1;		// Shift the byte by one bit
		SetSCLK(1);			// Set SCLK high
		SetSCLK(0);			// Set SCLK low
	}

	SetSDATA(1);			// Set SDATA input/high
	SetSCLK(1);				// Set SCLK high

	if (!GetSDATA())
	{
		SetSCLK(0);			// Set SCLK low
		return true;			// ACK from slave
	}
	else
	{
		SetSCLK(0);			// Set SCLK low
		return false;			// NACK from slave
	}
}



//------------------------------------------------------------------------------
// 	Routine:	Read
//	Inputs:	*data_in, send_ack (if true send the ACK signal else send NACK)
//	Outputs:	bool
//	Purpose:	Reads data from the I2C bus and return it in data_in.
//			Returns status.
//------------------------------------------------------------------------------
inline bool Read(unsigned char *data_in, bool send_ack)
{
	unsigned char index;

	*data_in = 0x00;

	SetSDATA(1);					// Set SDATA input/high
	SetSCLK(0);						// Set SCLK low

	// Get 8 bits from the device
	for (index = 0; index < 8; index++)
	{
		*data_in <<= 1;				// Shift the data right 1 bit
		SetSCLK(1);					// Set SCLK high
		//11182003 - Line moved...
		//SetSCLK(0);				// Set SCLK low
		*data_in |= GetSDATA();		// Read the data bit
		//11182003 - to here! (Fixed thanks to Andrew Seddon).
		SetSCLK(0);					// Set SCLK low
	}

	if (send_ack)
		SetSDATA(0);				// Set data pin to output/low to ACK the read
	else
		SetSDATA(1);				// Set data pin to input/high to NACK the read

	SetSCLK(1);						// Set SCLK high
	SetSCLK(0);						// Set SCLK low
	SetSDATA(0);					// Set SDATA output/low
	SetSDATA(1);					// Set SDATA input/high

	return true;
}


//------------------------------------------------------------------------------
// 	Routine:	SetSDATA
//	Inputs:	state
//	Outputs:	none
//	Purpose:	Set the I2C port SDATA pin to <state>.
//------------------------------------------------------------------------------
inline void SetSDATA(bool state)
{
	unsigned int i, d;
	
	if (state)
	{
		*pFIO0_DIR &= ~I2C_DATA;		// Set SDATA as input/high.
	}
	else
	{
		*pFIO0_INEN &= ~I2C_DATA;
		*pFIO0_FLAG_C = I2C_DATA;
		*pFIO0_DIR |= I2C_DATA;
		*pFIO0_FLAG_C = I2C_DATA;	// Set SDATA as output.
		*pFIO0_INEN |= I2C_DATA;
	}

	// Delay
	for (i = 0; i < I2C_Delay; i++)
	{
		asm("nop;");
	}
}



//------------------------------------------------------------------------------
// 	Routine:	SetSCLK
//	Inputs:	state
//	Outputs:	none
//	Purpose:	Set the I2C port SCLK pin to <state>.
//------------------------------------------------------------------------------
inline void SetSCLK(bool state)
{
	unsigned int i, d;
	
	if (state)
	{
		*pFIO0_FLAG_D |= I2C_CLK;		// Set SCLK high.
	}
	else
	{
		*pFIO0_FLAG_D &= ~I2C_CLK;	// Set SCLK low.
	}

	// Delay
	for (i = 0; i < I2C_Delay; i++)
	{
		asm("nop;");
	}
}


//------------------------------------------------------------------------------
// 	Routine:	GetSDATA
//	Inputs:	none
//	Outputs:	bool
//	Purpose:	Get the I2C port SDATA pin state.
//------------------------------------------------------------------------------
inline bool GetSDATA()
{
	return ((*pFIO0_FLAG_D & I2C_DATA) ? 1 : 0);	
}