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/* $Id$ */
/**
* True North Technologies - Revolution 2X Digital compass
*
* More info: http://www.tntc.com/
*
* This is a digital compass which uses magnetometers to measure the
* strength of the earth's magnetic field. Based on these measurements
* it provides a compass heading using NMEA formatted output strings.
* This is useful to supplement the heading provided by another GPS
* unit. A GPS heading is unreliable at slow speed or no speed.
*/
#include "gpsd.h"
#ifdef TNT_ENABLE
/*
* The True North compass won't start talking unless you ask it to. To
* wake it up, we query for its ID string just after each speed change
* in the autobaud hunt. The initializer will send it codes to start
* the flow of data.
*/
static void tnt_wakeup(struct gps_device_t *session)
{
(void)nmea_send(session->gpsdata.gps_fd, "@X?");
}
static void tnt_initializer(struct gps_device_t *session)
{
//nmea_send(session->gpsdata.gps_fd, "@BA?"); // Query current rate
//nmea_send(session->gpsdata.gps_fd, "@BA=8"); // Start HTM packet at 1Hz
/*
* Sending this twice seems to make it more reliable!!
* I think it gets the input on the unit synced up.
* The intent is to start HTM packet reporting at 1200 per minute.
*/
(void)nmea_send(session->gpsdata.gps_fd, "@BA=15");
(void)nmea_send(session->gpsdata.gps_fd, "@BA=15");
}
struct gps_type_t trueNorth = {
.typename = "True North", /* full name of type */
.trigger = " TNT1500", /* how to recognize this */
.channels = 0, /* not an actual GPS at all */
.wakeup = tnt_wakeup, /* wakeup by sending ID query */
.probe = NULL, /* no probe */
.initializer = tnt_initializer, /* no initializer */
.get_packet = packet_get, /* how to get a packet */
.parse_packet = nmea_parse_input, /* how to interpret a packet */
.rtcm_writer = NULL, /* Don't send */
.speed_switcher = NULL, /* no speed switcher */
.mode_switcher = NULL, /* no mode switcher */
.rate_switcher = NULL, /* no wrapup */
.cycle_chars = -1, /* not relevant, no rate switch */
.wrapup = NULL, /* no wrapup */
.cycle = 20, /* updates per second */
};
#endif
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