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Merge pull request #861 from a-f-G-U-C/NMEA-GPS-fixes

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fixes from PR #851, #858 ported to NMEA GPS
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Kevin Hester 2021-09-08 13:56:47 -07:00 committed by GitHub
commit 42986c852a
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2 changed files with 125 additions and 27 deletions
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141
src/gps/NMEAGPS.cpp
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@ -2,6 +2,12 @@
#include "NMEAGPS.h"
#include "RTC.h"
#include <TinyGPS++.h>
// GPS solutions older than this will be rejected - see TinyGPSDatum::age()
#define GPS_SOL_EXPIRY_MS 300 // in millis
#define NMEA_MSG_GXGSA "GNGSA" // GSA message (GPGSA, GNGSA etc)
static int32_t toDegInt(RawDegrees d)
{
int32_t degMult = 10000000; // 1e7
@ -21,6 +27,17 @@ bool NMEAGPS::setupGPS()
pinMode(PIN_GPS_PPS, INPUT);
#endif
// Currently disabled per issue #525 (TinyGPS++ crash bug)
// when fixed upstream, can be un-disabled to enable 3D FixType and PDOP
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
// see NMEAGPS.h
gsafixtype.begin(reader, NMEA_MSG_GXGSA, 2);
gsapdop.begin(reader, NMEA_MSG_GXGSA, 15);
DEBUG_MSG("Using " NMEA_MSG_GXGSA " for 3DFIX and PDOP\n");
#else
DEBUG_MSG("GxGSA NOT available\n");
#endif
return true;
}
@ -48,7 +65,7 @@ The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of s
t.tm_year = d.year() - 1900;
t.tm_isdst = false;
DEBUG_MSG("NMEA GPS time %d\n", t.tm_sec);
perhapsSetRTC(RTCQualityGPS, t);
return true;
@ -64,47 +81,117 @@ The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of s
*/
bool NMEAGPS::lookForLocation()
{
bool foundLocation = false;
// By default, TinyGPS++ does not parse GPGSA lines, which give us
// the 2D/3D fixType (see NMEAGPS.h)
// At a minimum, use the fixQuality indicator in GPGGA (FIXME?)
fixQual = reader.fixQuality();
// uint8_t fixtype = reader.fixQuality();
// hasValidLocation = ((fixtype >= 1) && (fixtype <= 5));
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
fixType = atoi(gsafixtype.value()); // will set to zero if no data
DEBUG_MSG("FIX QUAL=%d, TYPE=%d\n", fixQual, fixType);
#endif
// check if GPS has an acceptable lock
if (! hasLock())
return false;
// check if a complete GPS solution set is available for reading
// tinyGPSDatum::age() also includes isValid() test
// FIXME
if (! ((reader.location.age() < GPS_SOL_EXPIRY_MS) &&
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
(gsafixtype.age() < GPS_SOL_EXPIRY_MS) &&
#endif
(reader.time.age() < GPS_SOL_EXPIRY_MS) &&
(reader.date.age() < GPS_SOL_EXPIRY_MS)))
{
// DEBUG_MSG("SOME data is TOO OLD\n");
return false;
}
// Is this a new point or are we re-reading the previous one?
if (! reader.location.isUpdated())
return false;
// Start reading the data
auto loc = reader.location.value();
// Some GPSes (Air530) seem to send a zero longitude when the current fix is bogus
// Bail out EARLY to avoid overwriting previous good data (like #857)
if(toDegInt(loc.lat) == 0) {
DEBUG_MSG("Ignoring bogus NMEA position\n");
return false;
}
// Dilution of precision (an accuracy metric) is reported in 10^2 units, so we need to scale down when we use it
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
dop = TinyGPSPlus::parseDecimal(gsapdop.value());
#else
// FIXME! naive PDOP emulation (assumes VDOP==HDOP)
// correct formula is PDOP = SQRT(HDOP^2 + VDOP^2)
dop = 1.41 * reader.hdop.value();
#endif
// Discard incomplete or erroneous readings
if (dop == 0)
return false;
latitude = toDegInt(loc.lat);
longitude = toDegInt(loc.lng);
geoidal_height = reader.geoidHeight.meters();
#ifdef GPS_ALTITUDE_HAE
altitude = reader.altitude.meters() + geoidal_height;
#else
altitude = reader.altitude.meters();
#endif
// positional timestamp
struct tm t;
t.tm_sec = reader.time.second();
t.tm_min = reader.time.minute();
t.tm_hour = reader.time.hour();
t.tm_mday = reader.date.day();
t.tm_mon = reader.date.month() - 1;
t.tm_year = reader.date.year() - 1900;
t.tm_isdst = false;
pos_timestamp = mktime(&t);
// Nice to have, if available
if (reader.satellites.isUpdated()) {
setNumSatellites(reader.satellites.value());
}
// Diminution of precision (an accuracy metric) is reported in 10^2 units, so we need to scale down when we use it
if (reader.hdop.isUpdated()) {
dop = reader.hdop.value();
}
if (reader.course.isUpdated()) {
if (reader.course.isUpdated() && reader.course.isValid()) {
heading = reader.course.value() * 1e3; // Scale the heading (in degrees * 10^-2) to match the expected degrees * 10^-5
}
if (reader.altitude.isUpdated())
altitude = reader.altitude.meters();
/*
// REDUNDANT?
// expect gps pos lat=37.520825, lon=-122.309162, alt=158
DEBUG_MSG("new NMEA GPS pos lat=%f, lon=%f, alt=%d, dop=%g, heading=%f\n",
latitude * 1e-7, longitude * 1e-7, altitude, dop * 1e-2,
heading * 1e-5);
*/
return true;
}
if (reader.location.isUpdated()) {
auto loc = reader.location.value();
latitude = toDegInt(loc.lat);
longitude = toDegInt(loc.lng);
// Some GPSes (Air530) seem to send a zero longitude when the current fix is bogus
if(longitude == 0)
DEBUG_MSG("Ignoring bogus NMEA position\n");
else {
foundLocation = true;
// expect gps pos lat=37.520825, lon=-122.309162, alt=158
DEBUG_MSG("new NMEA GPS pos lat=%f, lon=%f, alt=%d, hdop=%g, heading=%f\n", latitude * 1e-7, longitude * 1e-7, altitude,
dop * 1e-2, heading * 1e-5);
}
bool NMEAGPS::hasLock()
{
// Using GPGGA fix quality indicator
if (fixQual >= 1 && fixQual <= 5) {
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
// Use GPGSA fix type 2D/3D (better) if available
if (fixType == 3 || fixType == 0) // zero means "no data received"
#endif
return true;
}
return foundLocation;
return false;
}
bool NMEAGPS::whileIdle()
{
bool isValid = false;

11
src/gps/NMEAGPS.h
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@ -12,6 +12,15 @@
class NMEAGPS : public GPS
{
TinyGPSPlus reader;
uint8_t fixQual = 0; // fix quality from GPGGA
#ifndef TINYGPS_OPTION_NO_CUSTOM_FIELDS
// (20210908) TinyGps++ can only read the GPGSA "FIX TYPE" field
// via optional feature "custom fields", currently disabled (bug #525)
TinyGPSCustom gsafixtype; // custom extract fix type from GPGSA
TinyGPSCustom gsapdop; // custom extract PDOP from GPGSA
uint8_t fixType = 0; // fix type from GPGSA
#endif
public:
virtual bool setupGPS();
@ -38,4 +47,6 @@ class NMEAGPS : public GPS
* @return true if we've acquired a new location
*/
virtual bool lookForLocation();
virtual bool hasLock();
};