i2c.c

LPC23XX ARM的驱动程序库

/*****************************************************************************
 *   i2c.c:  I2C C file for NXP LPC23xx/24xx Family Microprocessors
 *
 *   Copyright(C) 2006, NXP Semiconductor
 *   All rights reserved.
 *
 *   History
 *   2006.07.19  ver 1.00    Prelimnary version, first Release
 *
*****************************************************************************/
#include "LPC23xx.h"                        /* LPC23xx/24xx definitions */
#include "type.h"
#include "irq.h"
#include "i2c.h"

volatile DWORD I2CMasterState = I2C_IDLE;
volatile DWORD I2CSlaveState = I2C_IDLE;

volatile DWORD I2CCmd;
volatile DWORD I2CMode;

volatile BYTE I2CMasterBuffer[BUFSIZE];
volatile BYTE I2CSlaveBuffer[BUFSIZE];
volatile DWORD I2CCount = 0;
volatile DWORD I2CReadLength;
volatile DWORD I2CWriteLength;

volatile DWORD RdIndex = 0;
volatile DWORD WrIndex = 0;

/* 
From device to device, the I2C communication protocol may vary, 
in the example below, the protocol uses repeated start to read data from or 
write to the device:
For master read: the sequence is: STA,Addr(W),offset,RE-STA,Addr(r),data...STO 
for master write: the sequence is: STA,Addr(W),length,RE-STA,Addr(w),data...STO
Thus, in state 8, the address is always WRITE. in state 10, the address could 
be READ or WRITE depending on the I2CCmd.
*/   

/*****************************************************************************
** Function name:		I2C0MasterHandler
**
** Descriptions:		I2C0 interrupt handler, deal with master mode
**				only.
**
** parameters:			None
** Returned value:		None
** 
*****************************************************************************/
void I2C0MasterHandler (void) __irq 
{
    BYTE StatValue;

    /* this handler deals with master read and master write only */
    StatValue = I20STAT;
    IENABLE;				/* handles nested interrupt */	
    switch ( StatValue )
    {
	case 0x08:			/* A Start condition is issued. */
	I20DAT = I2CMasterBuffer[0];
	I20CONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
	I2CMasterState = I2C_STARTED;
	break;
	
	case 0x10:			/* A repeated started is issued */
	if ( I2CCmd == LM75_TEMP )
	{
		I20DAT = I2CMasterBuffer[2];
	}
	I20CONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
	I2CMasterState = I2C_RESTARTED;
	break;
	
	case 0x18:			/* Regardless, it's a ACK */
	if ( I2CMasterState == I2C_STARTED )
	{
	    I20DAT = I2CMasterBuffer[1+WrIndex];
	    WrIndex++;
	    I2CMasterState = DATA_ACK;
	}
	I20CONCLR = I2CONCLR_SIC;
	break;
	
	case 0x28:	/* Data byte has been transmitted, regardless ACK or NACK */
	case 0x30:
	if ( WrIndex != I2CWriteLength )
	{   
	    I20DAT = I2CMasterBuffer[1+WrIndex]; /* this should be the last one */
	    WrIndex++;
	    if ( WrIndex != I2CWriteLength )
	    {   
			I2CMasterState = DATA_ACK;
	    }
	    else
	    {
			I2CMasterState = DATA_NACK;
			if ( I2CReadLength != 0 )
			{
		    	I20CONSET = I2CONSET_STA;	/* Set Repeated-start flag */
		    	I2CMasterState = I2C_REPEATED_START;
			}
		}
	}
	else
	{
	    if ( I2CReadLength != 0 )
	    {
			I20CONSET = I2CONSET_STA;	/* Set Repeated-start flag */
			I2CMasterState = I2C_REPEATED_START;
	    }
	    else
	    {
			I2CMasterState = DATA_NACK;
	    }
	}
	I20CONCLR = I2CONCLR_SIC;
	break;
	
	case 0x40:	/* Master Receive, SLA_R has been sent */
	I20CONCLR = I2CONCLR_SIC;
	break;
	
	case 0x50:	/* Data byte has been received, regardless following ACK or NACK */
	case 0x58:
	I2CMasterBuffer[3+RdIndex] = I20DAT;
	RdIndex++;
	if ( RdIndex != I2CReadLength )
	{   
	    I2CMasterState = DATA_ACK;
	}
	else
	{
	    RdIndex = 0;
	    I2CMasterState = DATA_NACK;
	}
	I20CONSET = I2CONSET_AA;	/* assert ACK after data is received */
	I20CONCLR = I2CONCLR_SIC;
	break;
	
	case 0x20:			/* regardless, it's a NACK */
	case 0x48:
	I20CONCLR = I2CONCLR_SIC;
	I2CMasterState = DATA_NACK;
	break;
	
	case 0x38:			/* Arbitration lost, in this example, we don't
					deal with multiple master situation */
	default:
	I20CONCLR = I2CONCLR_SIC;	
	break;
    }
    IDISABLE;
    VICVectAddr = 0;		/* Acknowledge Interrupt */
}

/*****************************************************************************
** Function name:		I2CStart
**
** Descriptions:		Create I2C start condition, a timeout
**				value is set if the I2C never gets started,
**				and timed out. It's a fatal error. 
**
** parameters:			None
** Returned value:		true or false, return false if timed out
** 
*****************************************************************************/
DWORD I2CStart( void )
{
    DWORD timeout = 0;
    DWORD returnValue = FALSE;
 
    /*--- Issue a start condition ---*/
    I20CONSET = I2CONSET_STA;	/* Set Start flag */
    
    /*--- Wait until START transmitted ---*/
    while( 1 )
    {
		if ( I2CMasterState == I2C_STARTED )
		{
	    	returnValue = TRUE;
	    	break;	
		}
		if ( timeout >= MAX_TIMEOUT )
		{
	    	returnValue = FALSE;
	    	break;
		}
		timeout++;
    }
    return( returnValue );
}

/*****************************************************************************
** Function name:		I2CStop
**
** Descriptions:		Set the I2C stop condition, if the routine
**				never exit, it's a fatal bus error.
**
** parameters:			None
** Returned value:		true or never return
** 
*****************************************************************************/
DWORD I2CStop( void )
{
    I20CONSET = I2CONSET_STO;      /* Set Stop flag */ 
    I20CONCLR = I2CONCLR_SIC;  /* Clear SI flag */ 
            
    /*--- Wait for STOP detected ---*/
    while( I20CONSET & I2CONSET_STO );
    return TRUE;
}

/*****************************************************************************
** Function name:		I2CInit
**
** Descriptions:		Initialize I2C controller
**
** parameters:			I2c mode is either MASTER or SLAVE
** Returned value:		true or false, return false if the I2C
**				interrupt handler was not installed correctly
** 
*****************************************************************************/
DWORD I2CInit( DWORD I2cMode ) 
{
    PCONP |= (1 << 19);
    PINSEL1 &= ~0x03C00000;
	PINSEL1 |= 0x01400000;	/* set PIO0.27 and PIO0.28 to I2C0 SDA and SCK */
							/* function to 01 on both SDA and SCK. */
    /*--- Clear flags ---*/
    I20CONCLR = I2CONCLR_AAC | I2CONCLR_SIC | I2CONCLR_STAC | I2CONCLR_I2ENC;    

    /*--- Reset registers ---*/
    I20SCLL   = I2SCLL_SCLL;
    I20SCLH   = I2SCLH_SCLH;
    if ( I2cMode == I2CSLAVE )
    {
		I20ADR = LM75_ADDR;
    }    

    /* Install interrupt handler */	
    if ( install_irq( I2C0_INT, (void *)I2C0MasterHandler, HIGHEST_PRIORITY ) == FALSE )
    {
		return( FALSE );
    }
    I20CONSET = I2CONSET_I2EN;
    return( TRUE );
}

/*****************************************************************************
** Function name:		I2CEngine
**
** Descriptions:		The routine to complete a I2C transaction
**				from start to stop. All the intermitten
**				steps are handled in the interrupt handler.
**				Before this routine is called, the read
**				length, write length, I2C master buffer,
**				and I2C command fields need to be filled.
**				see i2cmst.c for more details. 
**
** parameters:			None
** Returned value:		true or false, return false only if the
**				start condition can never be generated and
**				timed out. 
** 
*****************************************************************************/
DWORD I2CEngine( void ) 
{
    I2CMasterState = I2C_IDLE;
    RdIndex = 0;
    WrIndex = 0;
    if ( I2CStart() != TRUE )
    {
		I2CStop();
		return ( FALSE );
    }

    while ( 1 )
    {
		if ( I2CMasterState == DATA_NACK )
		{
	    	I2CStop();
	    	break;
		}
    }    
    return ( TRUE );      
}

/******************************************************************************
**                            End Of File
******************************************************************************/