#include	<pic.h>#include	"..\delay.h"#include 	"i2c.h"/* *	I2C functions for HI-TECH PIC C - master mode only *//* * 	TIMING - see Philips document: THE I2C-BUS SPECIFICATION *//* * 	Send stop condition * 	  - data low-high while clock high */voidi2c_Stop(void){	/* don't assume SCL is high on entry */	SDA_LOW();					/* ensure data is low first */	SCL_HIGH();		DelayUs(I2C_TM_DATA_SU);	SCL_DIR = I2C_INPUT;		/* float clock high */
	DelayUs(I2C_TM_STOP_SU);	SDA_HIGH();					/* the low->high data transistion */	DelayUs(I2C_TM_BUS_FREE);	/* bus free time before next start */	SDA_DIR = I2C_INPUT;		/* float data high */	return;}/* * 	Send (re)start condition * 	  - ensure data is high then issue a start condition * 	  - see also i2c_Start() macro */voidi2c_Restart(void){	SCL_LOW();					/* ensure clock is low */	SDA_HIGH();					/* ensure data is high */	DelayUs(I2C_TM_DATA_SU);	SCL_DIR = I2C_INPUT;		/* clock pulse high */	DelayUs(I2C_TM_SCL_HIGH);	SDA_LOW();					/* the high->low transition */	DelayUs(I2C_TM_START_HD);	return;}/* * 	Send a byte to the slave * 	  - returns true on error */unsigned chari2c_SendByte(unsigned char byte){	signed char i;	for(i=7; i>=0; i--)	{		SCL_LOW();					/* drive clock low */				/* data hold time = 0, send data now */        SDA_DIR = ((byte>>i)&0x01);        if ((byte>>i)&0x01) {		/* bit to send */			SDA_HIGH();        }else {			SDA_LOW();        }		DelayUs(I2C_TM_DATA_SU);		SCL_DIR = I2C_INPUT;		/* float clock high */		if(i2c_WaitForSCL())		/* wait for clock release */			return TRUE;			/* bus error */		DelayUs(I2C_TM_SCL_HIGH);	/* clock high time */	}		return FALSE;}/* * 	send an address and data direction to the slave * 	  - 7-bit address (lsb ignored) * 	  - direction (FALSE = write ) */unsigned chari2c_SendAddress(unsigned char address, unsigned char rw){	return i2c_SendByte(address | (rw?1:0));}/* * 	Check for an acknowledge * 	  - returns ack or ~ack, or ERROR if a bus error */signed chari2c_ReadAcknowledge(void){	unsigned char ack;	SCL_LOW();						/* make clock is low */	SDA_DIR = I2C_INPUT;			/* disable data line - listen for ack */	DelayUs(I2C_TM_SCL_TO_DATA);	/* SCL low to data out valid */	SCL_DIR = I2C_INPUT;			/* float clock high */	DelayUs(I2C_TM_DATA_SU);	ack = SDA;						/* read the acknowledge */	/* wait for slave to release clock line after processing byte */	if(i2c_WaitForSCL())		return I2C_ERROR;	return ack;}/* * 	Read a byte from the slave * 	  - returns the byte, or I2C_ERROR if a bus error */inti2c_ReadByte(void){	unsigned char i;	unsigned char byte = 0;	for(i=0; i<8; i++)	{		SCL_LOW();					/* drive clock low */		DelayUs(I2C_TM_SCL_LOW);	/* min clock low  period */		SDA_DIR = I2C_INPUT;		/* release data line */		SCL_DIR = I2C_INPUT;		/* float clock high */		if(i2c_WaitForSCL())			return I2C_ERROR;		DelayUs(I2C_TM_SCL_HIGH);		byte = byte << 1;		/* read the next bit */		byte |= SDA;	}	return (int)byte;}/* * 	Send an (~)acknowledge to the slave * 	  - status of I2C_LAST implies this is the last byte to be sent */voidi2c_SendAcknowledge(unsigned char status){	SCL_LOW();	if ( status & 0x01) {		SDA_LOW();				/* drive line low -> more to come */	}else { 		SDA_HIGH();	}	DelayUs(I2C_TM_DATA_SU);	SCL_DIR = I2C_INPUT;		/* float clock high */	DelayUs(I2C_TM_SCL_HIGH);	return;}/* * 	Send a byte to the slave and acknowledges the transfer * 	  - returns I2C_ERROR, ack or ~ack */signed chari2c_PutByte(unsigned char data){	if(i2c_SendByte(data))		return I2C_ERROR;	return i2c_ReadAcknowledge();	/* returns ack, ~ack */}/* * 	Get a byte from the slave and acknowledges the transfer * 	  - returns true on I2C_ERROR or byte */inti2c_GetByte(unsigned char more){	int byte;	if((byte = i2c_ReadByte()) == I2C_ERROR)		return I2C_ERROR;	i2c_SendAcknowledge(more);	return byte;}/* * 	Send an array of bytes to the slave and acknowledges the transfer * 	  - returns number of bytes not successfully transmitted */inti2c_PutString(const unsigned char *str, unsigned char length){	signed char error;	while(length)	{		if((error = i2c_PutByte(*str)) == I2C_ERROR)			return -(int)length;					/* bus error */		else			if(error)				return (int)length;					/* non acknowledge */		str++;		length--;	}	return FALSE;									/* everything OK */}/* * 	Reads number bytes from the slave, stores them at str and acknowledges the transfer * 	  - returns number of bytes not successfully read in */unsigned chari2c_GetString(unsigned char *str, unsigned char number){	int byte;	while(number)	{		if((byte = i2c_GetByte(number-1)) == I2C_ERROR)			return number;								/* bus error */		else			*str = (unsigned char)byte;		str++;		number--;	}	return FALSE;										/* everything OK */}/* * 	Opens communication with a device at address. mode * 	indicates I2C_READ or I2C_WRITE. * 	  - returns TRUE if address is not acknowledged */unsigned chari2c_Open(unsigned char address, unsigned char mode){	i2c_Start();	i2c_SendAddress(address, mode);	if(i2c_ReadAcknowledge()) 		return TRUE;	return FALSE;}
/* * 	wait for the clock line to be released by slow slaves * 	  - returns TRUE if SCL was not released after the * 	    time out period. * 	  - returns FALSE if and when SCL released */unsigned chari2c_WaitForSCL(void){	/* SCL_DIR should be input here */	if(!SCL)	{		DelayUs(I2C_TM_SCL_TMO);		/* if the clock is still low -> bus error */		if(!SCL)			return TRUE;	}	return FALSE;}voidi2c_Free(){	unsigned char ucI;	SDA_DIR=I2C_INPUT;	for(ucI=0;ucI!=9;ucI++)	{		SCL_HIGH();		DelayUs(5);		SCL_LOW();		DelayUs(5);	}}unsigned char i2c_read(unsigned char ucAdr){	unsigned char ucDat;	if (i2c_ReadFrom(ucAdr)==0)	{		ucDat=i2c_GetByte(I2C_MORE);		i2c_Stop();	}	return(ucDat);}