/* *	Serial port driver (uses bit-banging) *	for 16Cxx series parts. * * 	IMPORTANT: Compile this file with FULL optimization * *	Copyright (C)1996 HI-TECH Software. *	Freely distributable. */#include	<htc.h>/* *	Tunable parameters *//*	Xtal frequency */#define	XTAL		4000000/*	Baud rate	*/#define	BRATE		9600/*	Transmit and Receive port bits */#define	TxData		RB6				/* Map TxData to pin */#define	RxData		RB7				/* Map RxData to pin */#define	INIT_PORT	TRISB = 1<<7	/* set up I/O direction *//*	Don't change anything else */#define SCALER			10000000#define ITIME			4*SCALER/XTAL	/* Instruction cycle time */#if BRATE > 1200	#define	DLY			3				/* cycles per null loop */	#define	TX_OHEAD	13				/* overhead cycles per loop */#else	#define	DLY			9				/* cycles per null loop */	#define TX_OHEAD	14#endif#define	RX_OHEAD		12				/* receiver overhead per loop */#define	DELAY(ohead)	(((SCALER/BRATE)-(ohead*ITIME))/(DLY*ITIME))voidputch(char c){	unsigned char	bitno;#if BRATE > 1200	unsigned char	dly;#else	unsigned int	dly;#endif	INIT_PORT;	TxData = 0;			/* start bit */	bitno = 12;	do {		dly = DELAY(TX_OHEAD);	/* wait one bit time */		do			/* waiting in delay loop */ ;		while(--dly);		if(c & 1)			TxData = 1;		if(!(c & 1))			TxData = 0;		c = (c >> 1) | 0x80;	} while(--bitno);NOP();}chargetch(void){	unsigned char	c, bitno;#if BRATE > 1200	unsigned char	dly;#else	unsigned int	dly;#endif	for(;;) {		while(RxData)			continue;		/* wait for start bit */		dly = DELAY(3)/2;		do							/* waiting in delay loop */ ;		while(--dly);		if(RxData)			continue;		/* twas just noise */		bitno = 8;		c = 0;		do {			dly = DELAY(RX_OHEAD);			do							/* waiting in delay loop */ ;			while(--dly);			c = (c >> 1) | (RxData << 7);		} while(--bitno);		return c;	}}chargetche(void){	char c;	putch(c = getch());	return c;}