i2c_state=I2C_TIME_OUT;		return (i2c_state);	}									// I2C master receive timeout	else {		return(i2c_state); 	}									// Return I2C current state}/*-------------------------------------------------------------------------upsd_i2c_slave_Xmit(Data_Ptr, N_Ptr)This function is used to transmit data to master, only for slave.Data_Ptr	- unsigned char*			- address pointer of transmit bufferN_Ptr		- unsigned char*			- the length of data buffer transmitted to master. Returns:I2C_SX_END		6			//Slave Mode - transmission is completeI2C_TIME_OUT	9			//I2C Timed OutI2C_NACK		13			//I2C NACK (No Acknowledge)I2C_BUSLOST		14			//I2C bus lost-------------------------------------------------------------------------*/unsigned char upsd_i2c_slave_Xmit(unsigned char* Data_Ptr,									unsigned char* N_Ptr){	EA=0;	i2c_xmit_buf=Data_Ptr; 						// Initialize pointer to transmit buffer	i2c_master = 0;	i2c_xmitr = 1;								// Set up for Slave transmitter	S1CON &= ~STO;								// Disable STOP control bit	i2c_data_index=0;	S1DAT = i2c_xmit_buf[i2c_data_index];  		// Send first data to master	i2c_data_index++;	i2c_state=I2C_SX; 							// Set I2C current status	EA=1;	if(upsd_i2c_Timeout(I2C_SX,10000)==1){		S1CON&=~ENI;i2c_slave_addressed=0;i2c_state=I2C_TIME_OUT;return(i2c_state);	}	   										// I2C slave timeout return	else {		*N_Ptr=i2c_data_index;return(i2c_state);	}			    							// return current I2C state and the length												// of the data buffer transmitted to master}/*-------------------------------------------------------------------------upsd_i2c_slave_Recv(Data_Ptr, N_Ptr)This function is used to receive data from a master while in slave mode.Data_Ptr	- unsigned char*			- address pointer to receive bufferN_Ptr		- unsigned char*			- the length of received data from the master. Returns:I2C_TIME_OUT	9			//I2C Timed OutI2C_SR_END		11			//Slave Mode - reception completeI2C_NACK		13			//I2C NACK (No Acknowledge)I2C_BUSLOST		14			//I2C bus lostI2C_SX_APP		15			//Slave to transmit data to master-------------------------------------------------------------------------*/unsigned char upsd_i2c_slave_Recv(unsigned char* Data_Ptr,									unsigned char* N_Ptr){	EA=0;	S1CON&=~ENI;	i2c_rcv_buf=Data_Ptr;						// initialize pointer to receive buffer	i2c_master = 0;  	i2c_xmitr = 0;								// Set to Slave transmitter	i2c_data_index=0;	i2c_state=I2C_SR;	 						// Set I2C current status to Slave Read	S1CON|=ENI;	EA=1;	if(upsd_i2c_Timeout(I2C_SR,10000)==1){		S1CON&=~ENI;i2c_slave_addressed=0;i2c_state=I2C_TIME_OUT; return(i2c_state); 	}	    									// Slave receive timeout	else {		*N_Ptr=i2c_data_index; return(i2c_state);	}											// Return I2C current state}/*------------------------------------------------------------------------	 I2C Interrupt Service RoutineThere are several types of interrupts handled by the ISR.1. The address packet has been transmitted by master or received by slave with AA=1.2. The data has been transmitted or received by master.3. The data has been transmitted or recieved by addressed slave with AA=1.4. The STOP condition has been received by addressed slave with AA=1.------------------------------------------------------------------------*/ void i2c_isr (void) interrupt I2C_VECTOR using 2 {		i2c_sta=S1STA;												// Store S1STA register	S1STA&=~INTR;											    // Clear INTR flag	toggle=0;	//------Master transmit operation--------------------------------------------	if (i2c_master & i2c_xmitr){							// master transmitter mode		if ((i2c_sta & BLOST) !=0){ 						// if bus lost, read dummybyte to turn to Slave mode			dummybyte=S1DAT;			i2c_state=I2C_BUSLOST;							// Indicate the bus was lost		}			else if ((i2c_sta & _ACKREP) !=0){			S1CON |=STO;			S1DAT=dummy; 									// if no ACK, send STOP condition to Bus			i2c_state=I2C_NACK;								// Indicate NACK (no ACK)		}		else		{				if((i2c_data_index)<=(i2c_data_len-1))			{				S1DAT = i2c_xmit_buf[i2c_data_index];	 	//send data from Master				i2c_data_index++;  							//increment data-pointer			}			else if(i2c_data_index==i2c_data_len)			{   				S1CON |= STO;								// set STO (stop bit) for last data byte to be sent				S1DAT=dummy;				i2c_state=I2C_MX_END;						// Indicate the Master transmission is complete			}		}	}	//------Master receive operation--------------------------------------------	if (i2c_master & ~i2c_xmitr){							// master receive mode		//Handle interrupt in address field		if(((S1CON&AA)==0)& (i2c_data_index==0))		{			if ((i2c_sta & _ACKREP) !=0){				S1CON |=STO;				dummybyte=S1DAT; 											i2c_state=I2C_NACK;							// indicate NACK (no ACK)				return;  												}			else			{				dummybyte=S1DAT;	 						//dummy read 				if(i2c_data_len!=1)S1CON |= AA;   			//enable ACK to prepare to receive data from slave				i2c_data_index++;				return;			}		} 		//Handle reception of data		else		{			if(i2c_data_index<i2c_data_len)			{					i2c_rcv_buf[i2c_data_index-1] = S1DAT;	   		// Receive data				i2c_data_index++;						  		// Increment data-pointer				if(i2c_data_index==i2c_data_len){S1CON&=~AA;} 	// Disable ACK to return a NACK when																//	 master received the last byte of data.			}			else  							{   				S1CON |=STO;								// Generate a STOP condition on Bus				i2c_rcv_buf[i2c_data_index-1] = S1DAT;		// Receive the last byte of data				i2c_state=I2C_MR_END;						// Indicate Master reception is complete			}		}	}	//------slave operation--------------------------------------------	if(i2c_master==0){		//Handle STOP interrupt		if((i2c_sta&STOP)!=0){			if(i2c_slave_addressed==1){				if(i2c_xmitr==1){					i2c_state=I2C_SX_END;						// Indicate slave transmission is complete					i2c_slave_addressed=0;					    // Reset addressed flag					S1CON&=~ENI;								// Disable I2C to isolate slave from bus					return;				}				else				{					i2c_rcv_buf[i2c_data_index] = S1DAT;		// Get last byte of data from Master					i2c_slave_addressed=0;					    // Reset addressed flag					i2c_state=I2C_SR_END;						// Indicate the data has been received completely					S1CON&=~ENI;								// Disable I2C to isolate slave from bus					return;				}			}		}		//Handle Address field interrupt		else if(((S1CON&ADDR)!=0)&((S1CON&AA)!=0)){			S1CON&=~ADDR;										// Clear ADDR flag			i2c_slave_addressed=1;						    	// Set addressed flag bit													// if received address information, identify read or write command			if((i2c_sta&TX_MODE)!=0){				i2c_state=I2C_SX_APP;							// Indicate slave is required to transmit data to master				return;			}			else{				dummybyte=S1DAT;								// Dummy read				return;			}		}		//Handle data field interrupt		else if(i2c_slave_addressed==1)		{			if(i2c_xmitr==0)			{   								i2c_rcv_buf[i2c_data_index] = S1DAT;			// Get data byte from Master				i2c_data_index++;								// Increment data-pointer			}			else			{				if((i2c_sta &_ACKREP)!=0)				{						S1DAT=dummy; 								// Dummy write				}				else				{					S1DAT = i2c_xmit_buf[i2c_data_index];		// Send data					i2c_data_index++;							// Increment data-pointer				}			}		}	}}