[onewire] / serial.c

/***
 *** Serial Port driver for 12f1840 and kin
 ***/

#include "user.h"
#include "system.h"

#include <stdint.h>
#include <stdbool.h>


/* outgoing text buffer */
char outbuff[100];
char * outp = 0;
uint8_t outlen = 0;

/* incoming text buffer */
char inbuff[10];
uint8_t inlen = 0;


void serial_init(void)
{
    /* Enabling transmitter 26.1.1.1 page 259 - TX/CK I/O pin */
    TXSTAbits.TXEN = 1;
    TXSTAbits.SYNC = 0;
    RCSTAbits.SPEN = 1;
    /* Enabling receiver 26.1.2 page 262 - RX/DT I/O pin */
    RCSTAbits.CREN = 1;

    /* Select pins 4&5 as the uart - page 102 */
    APFCONbits.RXDTSEL = 1; /* RX/DT on RA5 */
    APFCONbits.TXCKSEL = 1; /* TX/CK on RA4 */
    TRISAbits.TRISA5 = 1;   /* RA5 as input  */
    TRISAbits.TRISA4 = 0;   /* RA4 as output */

    ANSELAbits.ANSA4 = 0; /* no analog */

#if _XTAL_FREQ != 4000000L
#error "Adjust serial port baudrate settings"
#endif
    
    /* assume 4MHz clock, 19k2 baud */
    TXSTAbits.BRGH = 0;
    BAUDCONbits.BRG16 = 1;
    SPBRG = 12;

    /* Enable interrupts */
    INTCONbits.GIE = 1;
    INTCONbits.PEIE = 1;

    /* enable uart receiver interupt */
    PIE1bits.RCIE = 1;
}


/* is the queue empty yet */
bool msg_empty(void)
{
    if (outp == 0) return 1;
    return 0;
}

/* new message in the queue */
void msg_write(const char *msg)
{
    char * p = outbuff + outlen;
    while (outlen < sizeof(outbuff) && *msg != 0) {
        *(p++) = *(msg++);
        outlen++;
    }
    *p = 0;
    if (outp == 0) {
        outp = outbuff;
        PIE1bits.TXIE = 1;
    }
}

void msg_writebyte(const char msg)
{
    if (outlen+1 >= (uint8_t)sizeof(outbuff)) return;
    outbuff[outlen++] = msg;
    outbuff[outlen] = 0;
    if (outp == 0) {
        outp = outbuff;
        PIE1bits.TXIE = 1;
    }
}

void putch(char data)
{
    msg_writebyte(data);
}

/* called from interrupt routine to send next char */
void msg_sendnext(void)
{
    /* we have finished, turn off the iterrupt */
    if (outp == 0 || *outp == 0) {
        PIE1bits.TXIE = 0;
        outp = 0;
        outlen = 0;
        return;
    }
    TXREG = *outp;
    outp++;
}

/* called from interrupt routine to receive next byte */
void msg_recvnext(void)
{
    while (PIR1bits.RCIF) {
        bool err = RCSTAbits.FERR;
        char new = RCREG;

        /* bad char, skip it */
        if (err) continue;

        /* our input buffer has overflowed */
        if (inlen > sizeof(inbuff)) return;

        /* keep this one */
        inbuff[inlen++] = new;
    }
}

bool msg_recvready(void)
{
    if (inlen > 0) return 1;
    return 0;
}

char msg_recv(void)
{
    if (inlen == 0) return 0;

    /* record and disable the interupt */
    bool in = PIE1bits.RCIE;
    PIE1bits.RCIE = 0;

    char new = inbuff[0];
    inlen--;

    /* shuffle them down one */
    for (char i=0;i<inlen;i++)
        inbuff[i] = inbuff[i+1];

    /* restore the interupt */
    PIE1bits.RCIE = in;
    return new;
}
Commit	Line	Data
	1	/***
	2	*** Serial Port driver for 12f1840 and kin
	3	***/
	4
	5	#include "user.h"
	6	#include "system.h"
	7
	8	#include <stdint.h>
	9	#include <stdbool.h>
	10
	11
	12	/* outgoing text buffer */
	13	char outbuff[100];
	14	char * outp = 0;
	15	uint8_t outlen = 0;
	16
	17	/* incoming text buffer */
	18	char inbuff[10];
	19	uint8_t inlen = 0;
	20
	21
	22	void serial_init(void)
	23	{
	24	/* Enabling transmitter 26.1.1.1 page 259 - TX/CK I/O pin */
	25	TXSTAbits.TXEN = 1;
	26	TXSTAbits.SYNC = 0;
	27	RCSTAbits.SPEN = 1;
	28	/* Enabling receiver 26.1.2 page 262 - RX/DT I/O pin */
	29	RCSTAbits.CREN = 1;
	30
	31	/* Select pins 4&5 as the uart - page 102 */
	32	APFCONbits.RXDTSEL = 1; /* RX/DT on RA5 */
	33	APFCONbits.TXCKSEL = 1; /* TX/CK on RA4 */
	34	TRISAbits.TRISA5 = 1; /* RA5 as input */
	35	TRISAbits.TRISA4 = 0; /* RA4 as output */
	36
	37	ANSELAbits.ANSA4 = 0; /* no analog */
	38
	39	#if _XTAL_FREQ != 4000000L
	40	#error "Adjust serial port baudrate settings"
	41	#endif
	42
	43	/* assume 4MHz clock, 19k2 baud */
	44	TXSTAbits.BRGH = 0;
	45	BAUDCONbits.BRG16 = 1;
	46	SPBRG = 12;
	47
	48	/* Enable interrupts */
	49	INTCONbits.GIE = 1;
	50	INTCONbits.PEIE = 1;
	51
	52	/* enable uart receiver interupt */
	53	PIE1bits.RCIE = 1;
	54	}
	55
	56
	57	/* is the queue empty yet */
	58	bool msg_empty(void)
	59	{
	60	if (outp == 0) return 1;
	61	return 0;
	62	}
	63
	64	/* new message in the queue */
	65	void msg_write(const char *msg)
	66	{
	67	char * p = outbuff + outlen;
	68	while (outlen < sizeof(outbuff) && *msg != 0) {
	69	(p++) = (msg++);
	70	outlen++;
	71	}
	72	*p = 0;
	73	if (outp == 0) {
	74	outp = outbuff;
	75	PIE1bits.TXIE = 1;
	76	}
	77	}
	78
	79	void msg_writebyte(const char msg)
	80	{
	81	if (outlen+1 >= (uint8_t)sizeof(outbuff)) return;
	82	outbuff[outlen++] = msg;
	83	outbuff[outlen] = 0;
	84	if (outp == 0) {
	85	outp = outbuff;
	86	PIE1bits.TXIE = 1;
	87	}
	88	}
	89
	90	void putch(char data)
	91	{
	92	msg_writebyte(data);
	93	}
	94
	95	/* called from interrupt routine to send next char */
	96	void msg_sendnext(void)
	97	{
	98	/* we have finished, turn off the iterrupt */
	99	if (outp == 0 \|\| *outp == 0) {
	100	PIE1bits.TXIE = 0;
	101	outp = 0;
	102	outlen = 0;
	103	return;
	104	}
	105	TXREG = *outp;
	106	outp++;
	107	}
	108
	109	/* called from interrupt routine to receive next byte */
	110	void msg_recvnext(void)
	111	{
	112	while (PIR1bits.RCIF) {
	113	bool err = RCSTAbits.FERR;
	114	char new = RCREG;
	115
	116	/* bad char, skip it */
	117	if (err) continue;
	118
	119	/* our input buffer has overflowed */
	120	if (inlen > sizeof(inbuff)) return;
	121
	122	/* keep this one */
	123	inbuff[inlen++] = new;
	124	}
	125	}
	126
	127	bool msg_recvready(void)
	128	{
	129	if (inlen > 0) return 1;
	130	return 0;
	131	}
	132
	133	char msg_recv(void)
	134	{
	135	if (inlen == 0) return 0;
	136
	137	/* record and disable the interupt */
	138	bool in = PIE1bits.RCIE;
	139	PIE1bits.RCIE = 0;
	140
	141	char new = inbuff[0];
	142	inlen--;
	143
	144	/* shuffle them down one */
	145	for (char i=0;i<inlen;i++)
	146	inbuff[i] = inbuff[i+1];
	147
	148	/* restore the interupt */
	149	PIE1bits.RCIE = in;
	150	return new;
	151	}
	152
	153