sci.c

CML CMX868 modem

//---------------------------------------------------------------------------------------------------
//	Project:-	DE8681
//  	Filename:-	SCI.C
//	Description:-	Routines for initialisation and use of the SCI for the PIC processor.
//	Programmer:-	D.T.F	
//	Version:-	2.0
//	Created:-	28th February 2002
//	Last modified:- 
//---------------------------------------------------------------------------------------------------
//	(C) Consumer Microcircuits Ltd 2002
//
//	This firmware was designed by:-
//			Consumer Microcircuits Ltd,
//			Langford, Maldon,
//			ESSEX
//			CM9 6WG.
//	in the UK for use with CML evaluation kits only and is based on UK originated technology.
//	Please contact
//			[e-mail]
//			[phone]
//	for licensing details.
//---------------------------------------------------------------------------------------------------

#define SCI_C

#include	"ef8681.h"

unsigned char sci_init(unsigned long int baud, unsigned char ninebits)
{
	int X;
	unsigned long tmp;
	
	/* calculate and set baud rate register */
	/* for asynchronous mode */
	tmp = 16UL * baud;
	X = (int)(FOSC/tmp) - 1;
	if((X>255) || (X<0))
	{
		tmp = 64UL * baud;
		X = (int)(FOSC/tmp) - 1;
		if((X>255) || (X<0))
		{
			return 1;	/* panic - baud rate unobtainable */
		}
		else
			BRGH = 0;	/* low baud rate */
	}
	else
	{
		BRGH = 1;	/* high baud rate */
	}
	SPBRG = X;	/* set the baud rate */

	SYNC = 0;	/* asynchronous */
	SPEN = 1;	/* enable serial port pins */
	CREN = 1;	/* enable reception */
	SREN = 0;	/* no effect */
	TXIE = 0;	/* disable tx interrupts */
	RCIE = 0;	/* disable rx interrupts */
	TX9  = ninebits?1:0;	/* 8- or 9-bit transmission */
	RX9  = ninebits?1:0;	/* 8- or 9-bit reception */
	TXEN = 1;	/* enable the transmitter */

	return 0;
}

void sci_putByte(unsigned char byte)
{
	while(!TXIF)	/* set when register is empty */
		continue;
	TXREG = byte;

	return;
}

unsigned char sci_getByte(void)
{
	while(!RCIF)	/* set when register is not empty */
		continue;
	
	return RCREG;	/* RXD9 and FERR are gone now */
}

unsigned char sci_checkOERR(void)
{
	if(OERR)	/* re-enable after overrun error */
	{
		CREN = 0;
		CREN = 1;
		return 1;
	}
	
	return 0;
}

#define sci_putNinth(bitnine)	(TX9D = bitnine?1:0;)

unsigned char sci_getNinth(void)
{
	while(!RCIF)
		continue;
	
	return RX9D;	/* RCIF is not cleared until RCREG is read */
}

unsigned char sci_getFERR(void)
{
	while(!RCIF)
		continue;
	
	return FERR;	/* RCIF is not cleared until RCREG is read */
}