path: root/sirf.c

/*
 * This is the gpsd driver for SiRF-II GPSes operating in binary mode.
 * It also handles uBlox, a SiRF derivative.
 *
 * The advantage: Reports climb/sink rate (raw-mode clients won't see this).
 * The disadvantages: Doesn't return PDOP or VDOP, just HDOP.
 *
 * Chris Kuethe, our SiRF expert, tells us:
 * 
 * "I don't see any indication in any of my material that PDOP, GDOP
 * or VDOP are output. There are quantities called Estimated
 * {Horizontal Position, Vertical Position, Time, Horizonal Velocity}
 * Error, but those are apparently only valid when SiRFDRive is
 * active."
 *
 * "(SiRFdrive is their Dead Reckoning augmented firmware. It
 * allows you to feed odometer ticks, gyro and possibly 
 * accelerometer inputs to the chip to allow it to continue 
 * to navigate in the absence of satellite information, and 
 * to improve fixes when you do have satellites.)"
 *
 * Why we don't use packet 42 (Geodetic Navigation Information): 
 *
 * Many versions of the SiRF protocol manual don't document 
 * this sentence at all.  Those that do may incorrectly
 * describe UTC Day, Hour, and Minute as 2-byte quantities,
 * not 1-byte. Chris Kuethe, our SiRF expert, tells us:
 *
 * "The Geodetic Navigation packet (0x29) was not fully
 * implemented in firmware prior to version 2.3.2. So for
 * anyone running 231.000.000 or earlier (including ES,
 * SiRFDRive, XTrac trains) you won't get UTC time. I don't
 * know what's broken in firmwares before 2.3.1..."
 *
 * To work around the incomplete implementation of this
 * packet in 231, we used to assume that only the altitude field
 * from this packet is valid.  But even this doesn't necessarily
 * seem to be the case.  Instead, we do our own computation 
 * of geoid separation now.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <stdio.h>

#include "gpsd.h"
#if defined(SIRFII_ENABLE) && defined(BINARY_ENABLE)

/* FIX ME -- get actual leap seconds from subframe data */
#define LEAP_SECONDS	13

#define HI(n)		((n) >> 8)
#define LO(n)		((n) & 0xff)

static u_int16_t sirf_write(int fd, u_int8_t *msg) {
   int       i, len, ok, crc;
   char	     buf[MAX_PACKET_LENGTH*2];

   len = (msg[2] << 8) | msg[3];

   /* calculate CRC */
   crc = 0;
   for (i = 0; i < len; i++)
	crc += msg[4 + i];
   crc &= 0x7fff;

   /* enter CRC after payload */
   msg[len + 4] = (u_int8_t)((crc & 0xff00) >> 8);
   msg[len + 5] = (u_int8_t)( crc & 0x00ff);

   buf[0] = '\0';
   for (i = 0; i < len+8; i++)
       sprintf(buf+strlen(buf), " %02x", msg[i]);
   gpsd_report(4, "Writing SiRF control type %02x:%s\n", msg[4], buf);
   ok = write(fd, msg, len+8) == len+8;
   tcdrain(fd);
   return(ok);
}

static int sirf_speed(int ttyfd, int speed) 
/* change speed in binary mode */
{
   u_int8_t msg[] = {0xa0, 0xa2, 0x00, 0x09,
                     0x86, 
                     0x0, 0x0, 0x12, 0xc0,	/* 4800 bps */
		     0x08,			/* 8 data bits */
		     0x01,			/* 1 stop bit */
		     0x00,			/* no parity */
		     0x00,			/* reserved */
                     0x00, 0x00, 0xb0, 0xb3};

   msg[7] = HI(speed);
   msg[8] = LO(speed);
   return (sirf_write(ttyfd, msg));
}

static int sirf_to_nmea(int ttyfd, int speed) 
/* switch from binary to NMEA at specified baud */
{
   u_int8_t msg[] = {0xa0, 0xa2, 0x00, 0x18,
                     0x81, 0x02,
                     0x01, 0x01, /* GGA */
                     0x00, 0x00, /* suppress GLL */
                     0x01, 0x01, /* GSA */
                     0x05, 0x01, /* GSV */
                     0x01, 0x01, /* RMC */
                     0x00, 0x00, /* suppress VTG */
                     0x00, 0x01, 0x00, 0x01,
                     0x00, 0x01, 0x00, 0x01,
                     0x12, 0xc0, /* 4800 bps */
                     0x00, 0x00, 0xb0, 0xb3};

   msg[26] = HI(speed);
   msg[27] = LO(speed);
   return (sirf_write(ttyfd, msg));
}

#define getb(off)	(buf[off])
#define getw(off)	((short)((getb(off) << 8) | getb(off+1)))
#define getl(off)	((int)((getw(off) << 16) | (getw(off+2) & 0xffff)))

static void sirfbin_mode(struct gps_device_t *session, int mode)
{
    if (mode == 0) {
	gpsd_switch_driver(session, "SiRF-II NMEA");
	sirf_to_nmea(session->gpsdata.gps_fd,session->gpsdata.baudrate);
	session->gpsdata.driver_mode = 0;
    }
}

int sirf_parse(struct gps_device_t *session, unsigned char *buf, int len)
{
    int	st, i, j, cn, navtype, mask;
    char buf2[MAX_PACKET_LENGTH*3] = "";

    buf2[0] = '\0';
    for (i = 0; i < len; i++)
	sprintf(buf2+strlen(buf2), "%02x", buf[i]);
    gpsd_report(5, "Raw SiRF packet type %d length %d: %s\n", buf[0],len,buf2);
    snprintf(session->gpsdata.tag,sizeof(session->gpsdata.tag),"MID%d",buf[0]);

    switch (buf[0])
    {
    case 0x02:		/* Measure Navigation Data Out */
	mask = 0;
	/* position/velocity is bytes 1-18 */
	ecef_to_wgs84fix(&session->gpsdata.fix, 
		    getl(1), getl(5), getl(9),
		    getw(13)/8.0, getw(15)/8.0, getw(17)/8.0);
	/* WGS 84 geodesy parameters */
	/* fix status is byte 19 */
	navtype = getb(19);
	session->gpsdata.status = STATUS_NO_FIX;
	session->gpsdata.fix.mode = MODE_NO_FIX;
	if (navtype & 0x80)
	    session->gpsdata.status = STATUS_DGPS_FIX;
	else if ((navtype & 0x07) > 0 && (navtype & 0x07) < 7)
	    session->gpsdata.status = STATUS_FIX;
	if ((navtype & 0x07) == 4 || (navtype & 0x07) == 6)
	    session->gpsdata.fix.mode = MODE_3D;
	else if (session->gpsdata.status)
	    session->gpsdata.fix.mode = MODE_2D;
	if (session->gpsdata.fix.mode == MODE_3D)
	    mask |= ALTITUDE_SET;
	gpsd_report(4, "MND 0x02: Navtype = 0x%0x, Status = %d, mode = %d\n", 
		    navtype,session->gpsdata.status,session->gpsdata.fix.mode);
	/* byte 20 is HDOP, see below */
	/* byte 21 is "mode 2", not clear how to interpret that */ 
	session->gpsdata.fix.time = session->gpsdata.sentence_time
	    = gpstime_to_unix(getw(22), getl(24)*1e-2, -LEAP_SECONDS);
#ifdef NTPSHM_ENABLE
	session->time_seen |= TIME_SEEN_GPS_2;
	if (IS_HIGHEST_BIT(session->time_seen,TIME_SEEN_GPS_2))
	    ntpshm_put(session, session->gpsdata.fix.time);
#endif /* NTPSHM_ENABLE */

	gpsd_binary_fix_dump(session, buf2);
	/* fix quality data */
	session->gpsdata.hdop = getb(20)/5.0;
	session->gpsdata.satellites_used = getb(28);
	for (i = 0; i < MAXCHANNELS; i++)
	    session->gpsdata.used[i] = getb(29+i);
	session->gpsdata.pdop = session->gpsdata.vdop = 0.0;
	gpsd_binary_quality_dump(session, buf2 + strlen(buf2));
	gpsd_report(3, "<= GPS: %s", buf2);
	return mask | TIME_SET | LATLON_SET | TRACK_SET | SPEED_SET | STATUS_SET | MODE_SET | HDOP_SET;

    case 0x04:		/* Measured tracker data out */
	/*
	 * The freaking brain-dead SiRF chip doesn't obey its own
	 * rate-control command for 04, at least at firmware rev. 231, 
	 * so we have to do our own rate-limiting here...
	 */
	if (session->counter % 5)
	    break;
	gpsd_zero_satellites(&session->gpsdata);
	for (i = st = 0; i < MAXCHANNELS; i++) {
	    int good, off = 8 + 15 * i;
	    session->gpsdata.PRN[st]       = getb(off);
	    session->gpsdata.azimuth[st]   = (int)((getb(off+1)*3)/2.0);
	    session->gpsdata.elevation[st] = (int)(getb(off+2)/2.0);
	    cn = 0;
	    for (j = 0; j < 10; j++)
		cn += getb(off+5+j);
	    session->gpsdata.ss[st] = cn/10;
	    // session->gpsdata.used[st] = (getw(off+3) == 0xbf);
	    good = session->gpsdata.PRN[st] && 
		session->gpsdata.azimuth[st] && 
		session->gpsdata.elevation[st];
	    session->gpsdata.sentence_time
		= gpstime_to_unix(getw(1), getl(3)*1e-2, -LEAP_SECONDS);
#ifdef NTPSHM_ENABLE
	    session->time_seen |= TIME_SEEN_GPS_1;
	    if (IS_HIGHEST_BIT(session->time_seen,TIME_SEEN_GPS_1))
		ntpshm_put(session, session->gpsdata.sentence_time);
#endif /* NTPSHM_ENABLE */
#ifdef __UNUSED__
	    gpsd_report(4, "PRN=%2d El=%3.2f Az=%3.2f ss=%3d stat=%04x %c\n",
			getb(off), 
			getb(off+2)/2.0, 
			(getb(off+1)*3)/2.0,
			cn/10, 
			getw(off+3),
			good ? '*' : ' ');
#endif /* UNUSED */
	    if (good)
		st += 1;
	}
	session->gpsdata.satellites = st;
	gpsd_binary_satellite_dump(session, buf2);
	gpsd_report(4, "MTD 0x04: %d satellites\n", st);
	gpsd_report(3, "<= GPS: %s", buf2);
	return TIME_SET | SATELLITE_SET;

    case 0x06:		/* Software Version String */
	gpsd_report(4,"FV  0x06: Firmware version: %s\n",session->outbuffer+5);
	if (strstr(session->outbuffer+5, "ES"))
	    gpsd_report(4, "Firmware has XTrac capability\n");
	gpsd_report(4, "Driver state flags are: %0x\n", session->driverstate);
	return 0;

    case 0x08:
	/*
	 * Chris Kuethe says:
	 * "Message 8 is generated as the data is received. It is not
	 * buffered on the chip. So when you enable message 8, you'll
	 * get on subframe every 6 seconds.  Of the data received, the
	 * almanac and ephemeris are buffered and stored, so you can
	 * query them at will. Alas, the time parameters are not
	 * stored, which is really lame, as the UTC-GPS correction
	 * changes 1 second every few years. Maybe."
	 */
	break;

    case 0x09:		/* CPU Throughput */
	gpsd_report(4, 
		    "THR 0x09: SegStatMax=%.3f, SegStatLat=%3.f, AveTrkTime=%.3f, Last MS=%3.f\n", 
		    (float)getw(1)/186, (float)getw(3)/186, 
		    (float)getw(5)/186, getw(7));
    	return 0;

    case 0x0a:		/* Error ID Data */
	switch (getw(1))
	{
	case 2:
	    gpsd_report(4, "EID 0x0a type 2: Subframe error on PRN %ld\n", getl(5));
	    break;

	case 4107:
	    gpsd_report(4, "EID 0x0a type 4177: neither KF nor LSQ fix.\n", getl(5));
	    break;

	default:
	    gpsd_report(4, "EID 0x0a: Error ID type %d\n", getw(1));
	    break;
	}
	return 0;

    case 0x0b:		/* Command Acknowledgement */
	gpsd_report(4, "ACK 0x0b: %02x\n",getb(1));
    	return 0;

    case 0x0c:		/* Command NAcknowledgement */
	gpsd_report(4, "NAK 0x0c: %02x\n",getb(1));
    	return 0;

    case 0x0d:		/* Visible List */
	return 0;

    case 0x12:		/* OK To Send */
	gpsd_report(4, "OTS 0x12: send indicator = %d\n",getb(1));
	return 0;

    case 0x1b:		/* DGPS status (undocumented) */
	return 0;

    case 0x29:		/* Geodetic Navigation Information */
	return 0;

    case 0x32:		/* SBAS corrections */
	return 0;

    case 0x62:		/* uBlox Extended Measured Navigation Data */
	/* this packet is only sent by uBlox firmware from version 1.32 */
	mask =	LATLON_SET | ALTITUDE_SET | SPEED_SET | TRACK_SET | CLIMB_SET |
		STATUS_SET | MODE_SET | HDOP_SET | VDOP_SET | PDOP_SET;
	session->gpsdata.fix.latitude = getl(1) * RAD_2_DEG * 1e-8; 
	session->gpsdata.fix.longitude = getl(5) * RAD_2_DEG * 1e-8;
	session->gpsdata.fix.altitude = getl(9) * 1e-3;
	session->gpsdata.fix.speed = getl(13) * 1e-3;
	session->gpsdata.fix.climb = getl(17) * 1e-3;
	session->gpsdata.fix.track = getl(21) * RAD_2_DEG * 1e-8;

	navtype = getb(25);
	session->gpsdata.status = STATUS_NO_FIX;
	session->gpsdata.fix.mode = MODE_NO_FIX;
	if (navtype & 0x80)
	    session->gpsdata.status = STATUS_DGPS_FIX;
	else if ((navtype & 0x07) > 0 && (navtype & 0x07) < 7)
	    session->gpsdata.status = STATUS_FIX;
	if ((navtype & 0x07) == 4 || (navtype & 0x07) == 6)
	    session->gpsdata.fix.mode = MODE_3D;
	else if (session->gpsdata.status)
	    session->gpsdata.fix.mode = MODE_2D;
	gpsd_report(4, "EMND 0x62: Navtype = 0x%0x, Status = %d, mode = %d\n", 
		    navtype, session->gpsdata.status, session->gpsdata.fix.mode);

	if (navtype & 0x40) {		/* UTC corrected timestamp? */
	    mask |= TIME_SET;
	    session->gpsdata.nmea_date.tm_year = getw(26) - 1900;
	    session->gpsdata.nmea_date.tm_mon = getb(28) - 1;
	    session->gpsdata.nmea_date.tm_mday = getb(29);
	    session->gpsdata.nmea_date.tm_hour = getb(30);
	    session->gpsdata.nmea_date.tm_min = getb(31);
	    session->gpsdata.nmea_date.tm_sec = 0;
	    session->gpsdata.subseconds = ((unsigned short)getw(32))*1e-3;
	    session->gpsdata.fix.time = session->gpsdata.sentence_time
		= mkgmtime(&session->gpsdata.nmea_date)+session->gpsdata.subseconds;
#ifdef NTPSHM_ENABLE
	    session->time_seen |= TIME_SEEN_UTC_2;
	    if (IS_HIGHEST_BIT(session->time_seen,TIME_SEEN_UTC_2))
		ntpshm_put(session, session->gpsdata.fix.time + 0.75);
#endif /* NTPSHM_ENABLE */
	}

	/* session->gpsdata.gdop = getb(34) / 5.0; */
	session->gpsdata.pdop = getb(35) / 5.0;
	session->gpsdata.hdop = getb(36) / 5.0;
	session->gpsdata.vdop = getb(37) / 5.0;
	/* session->gpsdata.tdop = getb(38) / 5.0; */
	return mask;

    case 0xff:		/* Debug messages */
	buf2[0] = '\0';
	for (i = 1; i < len; i++)
	    if (isprint(buf[i]))
		sprintf(buf2+strlen(buf2), "%c", buf[i]);
	    else
		sprintf(buf2+strlen(buf2), "\\x%02x", buf[i]);
	gpsd_report(4, "DD  0xff: %s\n", buf2);
	return 0;

    default:
	buf2[0] = '\0';
	for (i = 0; i < len; i++)
	    sprintf(buf2+strlen(buf2), "%02x", buf[i]);
	gpsd_report(1, "Unknown SiRF packet length %d: %s\n", len, buf2);
	return 0;
    }

    return 0;
}

static int sirfbin_parse_input(struct gps_device_t *session)
{
    int st;

    if (session->packet_type == SIRF_PACKET){
	st = sirf_parse(session, session->outbuffer+4, session->outbuflen-8);
	session->gpsdata.driver_mode = 1;
	return st;
    } else if (session->packet_type == NMEA_PACKET) {
	st = nmea_parse(session->outbuffer, &session->gpsdata);
	session->gpsdata.driver_mode = 0;
	return st;
    } else
	return 0;
}

static void sirfbin_initializer(struct gps_device_t *session)
/* poll for software version in order to check for old firmware */
{
    if (session->packet_type == NMEA_PACKET) {
	gpsd_report(1, "Switching chip mode to SiRF binary.\n");
	nmea_send(session->gpsdata.gps_fd, 
		  "$PSRF100,0,%d,8,1,0", session->gpsdata.baudrate);
	packet_sniff(session);
    }
    /* do this every time*/
    {
	u_int8_t dgpscontrol[] = {0xa0, 0xa2, 0x00, 0x07,
				 0x85, 0x01, 0x00, 0x00,
				 0x00, 0x00, 0x00,
				 0x00, 0x00, 0xb0, 0xb3};
	u_int8_t sbasparams[] = {0xa0, 0xa2, 0x00, 0x06,
				 0xaa, 0x00, 0x01, 0x00,
				 0x00, 0x00,
				 0x00, 0x00, 0xb0, 0xb3};
	u_int8_t versionprobe[] = {0xa0, 0xa2, 0x00, 0x02,
				 0x84, 0x00,
				 0x00, 0x00, 0xb0, 0xb3};
	gpsd_report(4, "Setting DGPS control to use SBAS...\n");
	sirf_write(session->gpsdata.gps_fd, dgpscontrol);
	gpsd_report(4, "Setting SBAS to auto/integrity mode...\n");
	sirf_write(session->gpsdata.gps_fd, sbasparams);
	gpsd_report(4, "Probing for firmware version...\n");
	sirf_write(session->gpsdata.gps_fd, versionprobe);
    }
}

static int sirfbin_speed(struct gps_device_t *session, int speed)
{
    return sirf_speed(session->gpsdata.gps_fd, speed);
}

/* this is everything we export */
struct gps_type_t sirf_binary =
{
    "SiRF-II binary",		/* full name of type */
    "$Ack Input105.",		/* expected response to SiRF PSRF105 */
    NULL,			/* no probe */
    sirfbin_initializer,	/* initialize the device */
    packet_get,			/* how to grab a packet */
    sirfbin_parse_input,	/* read and parse message packets */
    NULL,			/* send DGPS correction */
    sirfbin_speed,		/* we can change baud rate */
    sirfbin_mode,		/* there's a mode switcher */
    NULL,			/* caller needs to supply a close hook */
    1,				/* updates every second */
};
#endif /* defined(SIRFII_ENABLE) && defined(BINARY_ENABLE) */