//
//	qsmrecv.c	FD3S ECU Syncronized Serial and Asyncronus Gateway
//				for PIC18F252
//				2002(c) Kashi.
//
#include <pic18fxx2.h>

char	spibp, sendstat;

struct	sSPI_buf {
	char	CmdSeg;
	int		addr;
	char	data;
	char	dummy;
	char	lock;
} SPIbuf_in, SPIbuf_out, UARTbuf_in, UARTbuf_out;

void interrupt	ssp_in()
{
	char	i;

	// Insert your code here
	// check SPI int
	if(SSPIF){
		SSPIF = 0;									// clear int flag
		*((char *)&SPIbuf_in + spibp) = SSPBUF;		// receive data
		SSPBUF = *((char *)&SPIbuf_out + spibp);	// trans data

		if( ++spibp == 5 ){
			spibp = 0;
			if( !UARTbuf_in.lock && (sendstat == 1)){	// UART data ready
				for(i=0;i<4;i++)						// set send data
					*((char *)&SPIbuf_out + i) =
						*((char *)&UARTbuf_in + i);
				sendstat = 2;				// sending

			} else if( sendstat == 2){
				sendstat = 3;				// sending done

			} else if( !UARTbuf_out.lock && (sendstat == 3)){
				for(i=0;i<4;i++)						// pull read data
					*((char *)&UARTbuf_out + i) =
						*((char *)&SPIbuf_in + i);
				sendstat = 4;				// answer ready, clear transaction
				SPIbuf_out.CmdSeg = 0xff;	// idle, nop command
			} else if( sendstat == 0){
				if( (*((char *)&SPIbuf_in + 0) == 0xff) &&
					(*((char *)&SPIbuf_in + 1) == 'F') )
					RA0 = 0;
				else
					RA0 = 1;
			}

		}
	}
}

void main()
{
	char	c, bp;

	PORTA = 0xff;
	PORTB = 0x00;
	PORTC = 0xff;
	TRISA = 0xfe;
	TRISB = 0xfe;
	TRISC = 0x9f;
	ADCON1 = 0x06;
	SSPSTAT = 0x00;
	SSPCON1 = 0x34;
	TXSTA = 0x24;
	RCSTA = 0x90;
	SPBRG = 64;			// 38,400bps @40.00MHz
	PEIE = 1;			// peripheral interrupt enable
	GIE = 1;			// grobal interrupt enable

restart:
	RA0 = 1;					// LED off
	spibp = 0;
	UARTbuf_in.lock = 1;
	UARTbuf_out.lock = 1;
	SPIbuf_in.lock = 1;
	SPIbuf_out.lock = 1;
	SPIbuf_out.CmdSeg = 0xff;	// idle, nop command
	SSPIE = 0;					// SSP interrupt disable
	SSPBUF = 0xff;
	while(1){					// wait last char on frame
		if(SSPIF){
			SSPIF = 0;
			if( SSPBUF == 'S' ) break;
			SSPBUF = 0xff;
		}
	}
	CREN = 0; CREN = 1;			// clear error
	c = RCREG;					// dummy read
	SSPIE = 1;					// SSP interrupt enable
	RA0 = 0;					// LED on

reread:
	sendstat = 0;
	UARTbuf_in.lock = 1;
	for( bp = 0; bp < 4; bp++){
		while(!RCIF);					// wait receive char
		c = RCREG;	
		if( bp == 0 && c == 0xff){
			while(!TRMT);				// wait transmitter
			TXREG = 0x00;				// responce null char
			goto reread;
		}
		*((char *)&UARTbuf_in + bp) = c;
	}
	UARTbuf_in.lock = 0;				// data ready
	UARTbuf_out.lock = 0;				// output buffer ready
	sendstat = 1;						// sending request
	while(sendstat != 4){				// polling request done
		if(RCIF){						// receive UART, break?
			if( RCREG == 0xff ){
				TXREG = 0x00;			// responce null char
				goto restart;
			}
		}
	}

	UARTbuf_out.lock = 1;
	for( bp = 0; bp < 4; bp++){
		while(!TRMT);					// wait transmitter
		TXREG = *((char *)&UARTbuf_out + bp);
	}

	goto reread;
}