Unable to read data from GNSS Module with Core 2



  • Hi,

    My configuration is a Core2 stacked to a M5Stack GNSS Module, newly bought on M5Stack Store.

    I don't manage to receive valid data from the GPS Module. The Serial stream and the source code are copied below.

    Thank you in advance for your support,

    Regards,
    Philippe

    ``
    --- Settings: /dev/cu.usbserial-57130480381 115200,8,N,1
    --- RTS: active DTR: active BREAK: inactive
    --- CTS: inactive DSR: inactive RI: inactive CD: inactive
    --- software flow control: inactive
    --- hardware flow control: inactive
    --- serial input encoding: UTF-8
    --- serial output encoding: UTF-8
    --- EOL: CRLF
    --- filters: default
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 9960 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 11392 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 12828 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 14268 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 15710 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 17152 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 18599 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 20048 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 21519 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 22972 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 24435 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 25906 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 27544 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 29184 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 30819 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 32460 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 34108 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 35775 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 37424 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 39081 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 40724 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 42372 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 44017 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 45657 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 47299 0 0
    **** ***** 0.000000 *********** **** ********** ******** **** ****** ****** ***** *** ******** ****** *** 48941 0 0

    The Code is below :

    #include <M5Core2.h>
    #include "M5Module_GNSS.h"
    #include <TinyGPSPlus.h>
    #include <Adafruit_BMP280.h>
    #include <WiFiManager.h> // https://github.com/tzapu/WiFiManager
    #include <SPI.h>
    #include <WiFi.h>
    #include <MQTT.h>
    
    
    static void smartDelay(unsigned long ms);
    static void printFloat(float val, bool valid, int len, int prec);
    static void printInt(unsigned long val, bool valid, int len);
    static void printDateTime(TinyGPSDate &d, TinyGPSTime &t);
    static void printStr(const char *str, int len);
    
    TinyGPSPlus gps;
    static const double LONDON_LAT = 51.508131, LONDON_LON = -0.128002;
    
    
    //Fonction pour MQTT
    unsigned long lastMillis = 0;
    
    void setup()
    {
        //M5.begin(true, true, true, false, kMBusModeInput);  
        //M5.begin(); 
        M5.begin();
        
        Serial.begin(115200);
        while (!Serial)
            ;
    
    
        //Connexion du GPS
        Serial2.begin(115200, SERIAL_8N1, 13, 14);
    
        M5.Lcd.println();
        M5.Lcd.println(F(
            "Sats HDOP  Latitude   Longitude   Fix  Date       Time     Date Alt   "
            " Course Speed Card  Distance Course Card  Chars Sentences Checksum"));
        M5.Lcd.println(
            F("           (deg)      (deg)       Age                      Age  (m) "
              "   --- from GPS ----  ---- to London  ----  RX    RX        Fail"));
        M5.Lcd.println(F(
            "----------------------------------------------------------------------"
            "------------------------------------------------------------------"));
      
       
    
    }
    
    void loop()
    {
      
        printInt(gps.satellites.value(), gps.satellites.isValid(), 5);
        printFloat(gps.hdop.hdop(), gps.hdop.isValid(), 6, 1);
        //printFloat(gps.location.lat(), gps.location.isValid(), 11, 6);
        printFloat(gps.location.lat(), true, 11, 6);
    
        printFloat(gps.location.lng(), gps.location.isValid(), 12, 6);
        printInt(gps.location.age(), gps.location.isValid(), 5);
        printDateTime(gps.date, gps.time);
        printFloat(gps.altitude.meters(), gps.altitude.isValid(), 7, 2);
        printFloat(gps.course.deg(), gps.course.isValid(), 7, 2);
        printFloat(gps.speed.kmph(), gps.speed.isValid(), 6, 2);
        printStr(
            gps.course.isValid() ? TinyGPSPlus::cardinal(gps.course.deg()) : "*** ",
            6);
    
        unsigned long distanceKmToLondon =
            (unsigned long)TinyGPSPlus::distanceBetween(
                gps.location.lat(), gps.location.lng(), LONDON_LAT, LONDON_LON) /
            1000;
        printInt(distanceKmToLondon, gps.location.isValid(), 9);
    
        double courseToLondon = TinyGPSPlus::courseTo(
            gps.location.lat(), gps.location.lng(), LONDON_LAT, LONDON_LON);
    
        printFloat(courseToLondon, gps.location.isValid(), 7, 2);
    
        const char *cardinalToLondon = TinyGPSPlus::cardinal(courseToLondon);
    
        printStr(gps.location.isValid() ? cardinalToLondon : "*** ", 6);
    
        printInt(gps.charsProcessed(), true, 6);
        printInt(gps.sentencesWithFix(), true, 10);
        printInt(gps.failedChecksum(), true, 9);
        Serial.println();
    
        smartDelay(1000);
    
        if (millis() > 5000 && gps.charsProcessed() < 10)
            Serial.println(F("No GPS data received: check wiring"));
    
        
            
    }
    
    // This custom version of delay() ensures that the gps object
    // is being "fed".
    static void smartDelay(unsigned long ms) {
        unsigned long start = millis();
        do {
            while (Serial2.available()) gps.encode(Serial2.read());
        } while (millis() - start < ms);
    }
    
    static void printFloat(float val, bool valid, int len, int prec) {
        if (!valid) {
            while (len-- > 1) Serial.print('*');
            Serial.print(' ');
        } else {
            Serial.print(val, prec);
            int vi   = abs((int)val);
            int flen = prec + (val < 0.0 ? 2 : 1);  // . and -
            flen += vi >= 1000 ? 4 : vi >= 100 ? 3 : vi >= 10 ? 2 : 1;
            for (int i = flen; i < len; ++i) Serial.print(' ');
        }
        smartDelay(0);
    }
    
    static void printInt(unsigned long val, bool valid, int len) {
        char sz[32] = "*****************";
        if (valid) sprintf(sz, "%ld", val);
        sz[len] = 0;
        for (int i = strlen(sz); i < len; ++i) sz[i] = ' ';
        if (len > 0) sz[len - 1] = ' ';
        Serial.print(sz);
        smartDelay(0);
    }
    
    static void printDateTime(TinyGPSDate &d, TinyGPSTime &t) {
        if (!d.isValid()) {
            Serial.print(F("********** "));
        } else {
            char sz[32];
            sprintf(sz, "%02d/%02d/%02d ", d.month(), d.day(), d.year());
            Serial.print(sz);
        }
    
        if (!t.isValid()) {
            Serial.print(F("******** "));
        } else {
            char sz[32];
            sprintf(sz, "%02d:%02d:%02d ", t.hour(), t.minute(), t.second());
            Serial.print(sz);
        }
    
        printInt(d.age(), d.isValid(), 5);
        smartDelay(0);
    }
    
    static void printStr(const char *str, int len) {
        int slen = strlen(str);
        for (int i = 0; i < len; ++i) Serial.print(i < slen ? str[i] : ' ');
        smartDelay(0);
    }


  • have you tried diff baudrates for GNSS like 9600 or 38400 which is NEO chip default as per docs



  • Are you trying it inside building or outside as they don't often work inside buildings



  • @robski Thank you very much for your answer. I tried 115200, 57600 and 9600 without any success. I will try tomorrow the other one you gave in your message and will tell you.



  • @ajb2k3 Thank you very much for your help. I did the tests with the external antenna, outside, on the roof close to a window.



  • @fra222 Thanks a lot again. It is working perfectly now with the 38 400 baudrate. The precision is impressing !



  • @fra222 said in Unable to read data from GNSS Module with Core 2:

    @fra222 Thanks a lot again. It is working perfectly now with the 38 400 baudrate. The precision is impressing !

    good to hear that you have it sorted now @FRA222