Published June 15, 2021

RPi GPS Tracking Using CAT M1

GPS Tracking with Low power Technology(CAT M1)

BeginnerWork in progress1 hour679

Things used in this project

Hardware components

Raspberry Pi 1 Model A+

Any Raspberry Pi with 40 pin header can be used

Sixfab Raspberry Pi Cellular IoT Kit (LTE-M)

Software apps and online services

Sixfab Core

Story

I got a couple of Raspberry Pi(s) on my desk, so the idea was to use one of them as a GPS location for my vehicle. I needed an internet connection for Raspberry Pi on the vehicle. Neither Wifi nor Ethernet could be used in this use case.

Hence, I had to go with a cellular connection. Since I had very little data to transfer I used CAT M1 here. This has been done at a very prototype level which can be improved later.

Apart from Raspberry Pi, I will be using all the other main parts from Sixfab i.e the cellular module, Bridge for the module and RPi, SIM Card, antennas, which come in a single package.

Raspberry Pi Cellular IoT Kit (LTE-M)

The Hardware setup is pretty straightforward as shown in the figure below

Hardware Setup

Getting Internet Connection

Thanks to Ensar, for the Easy Getting Started guide with this kit, which literally took about 5 mins to get the cellular connection up ready and saving my time for GPS tracking part of this project.

Moreover, it gives me a remote terminal connection, which can be used for developing a project on this distant device. Please check Ensar's project for more details.

Remote Terminal on Sixfab Core

Commands required for GPS

The Telit ME910C1-WW Module in this kit has GNSS support. Right after getting the cellular internet connection, it is time to check the required AT commands for GNSS/GPS.

PS. The AT Command guides of all the modules mentions GNSS instead of GPS.

Will Thornton explains in his blog "What’s the Difference Between GNSS and GPS?"

GNSS (or Global Navigation Satellite System) is a broad term encompassing different types of satellite-based positioning, navigation and timing (PNT) systems used globally. GPS (or Global Positioning System) is one such type of Global Navigation Satellite System.

The GNSS-related AT command for the Telit ME910C1-WW Module is mentioned in section 3.23 of the AT commands Guide. We will need the following 2 commands.

AT$GPSP

Turning on/off the GNSS.

AT$GPSNMUN

Unsolicited NMEW Data Configuration

AT$GPSNMUN=2,0,0,0,0,1,0

Later, turn on the GNSS, using the following command

AT$GPSP=1

Then we can see the NMEA flow such as below.

...
$GPRMC,182144.00,A,3757.595246,N,01115.606721,E,0.0,0.0,240321,4.0,E,A,V*49
$GPRMC,182145.00,A,3757.595210,N,01115.606839,E,0.0,0.0,240321,4.0,E,A,V*42 
$GPRMC,182143.00,A,3757.595177,N,01115.606760,E,0.0,0.0,240321,4.0,E,A,V*4F
...

Turning into Script

So far, we have learned how we can get the raw data out of the module. Let's turn everything into a script and parse the NMEA data into Longitude and Latitude. The script written in python3 is shared below. Hence you can run it with python3 and get an output as follows.

Connecting Port.. 
Waiting for 30 seconds to get the fix
Receiving GPS data  
$GPRMC,182142.00,A,3757.324422,N,02916.602155,E,0.0,0.0,120121,4.0,E,A*32 
-----Parsing GPRMC-----  
Latitude: 37.95540703333333N 
Longitute: 121.276702583333332E

PS. In the upcoming project, I will pull the data to a map.

gps.py

# For Telit ME910C1-WW module


from time import sleep
import serial

portwrite = "/dev/ttyUSB3"
port = "/dev/ttyUSB3"

def parseGPS(data):
    print(data, end='') #prints raw data
    if data[0:6] == "$GPRMC":
        sdata = data.split(",")
        if sdata[2] == 'V':
            print("\nNo satellite data available.\n")
            return
        print("-----Parsing GPRMC-----")
        time = sdata[1][0:2] + ":" + sdata[1][2:4] + ":" + sdata[1][4:6]
        lat = decode(sdata[3]) #latitude
        dirLat = sdata[4]      #latitude direction N/S
        lon = decode(sdata[5]) #longitute
        dirLon = sdata[6]      #longitude direction E/W
        speed = sdata[7]       #Speed in knots
        trCourse = sdata[8]    #True course
        date = sdata[9][0:2] + "/" + sdata[9][2:4] + "/" + sdata[9][4:6] #date
        variation = sdata[10]  #variation
        degreeChecksum = sdata[13] #Checksum
        dc = degreeChecksum.split("*")
        degree = dc[0]        #degree
        checksum = dc[1]      #checksum

        latitude = lat.split() # parsing latitude
        longitute = lon.split() # parsing longitute

        print("\nLatitude: " + str(int(latitude[0]) + (float(latitude[2])/60)) + dirLat) 

        print("Longitute: " + str(int(longitute[0]) + (float(longitute[2])/60)) + dirLon)

        #print("time : %s, latitude : %s(%s), longitude : %s(%s), speed : %s,True Course : %s, Date : %s, Magnetic Variation : %s(%s),Checksum : %s "%   (time,lat,dirLat,lon,dirLon,speed,trCourse,date,variation,degree,checksum))

  
def decode(coord):
    #Converts DDDMM.MMMMM -> DD deg MM.MMMMM min
    x = coord.split(".")
    head = x[0]
    tail = x[1]
    deg = head[0:-2]
    min = head[-2:]
    return deg + " deg " + min + "." + tail + " min"

print("Connecting Port..")
try:
    serw = serial.Serial(portwrite, baudrate = 115200, timeout = 1,rtscts=True, dsrdtr=True)
    serw.write('AT$GPSNMUN=2,0,0,0,0,1,0\r'.encode())
    serw.write('AT$GPSP=1\r'.encode())
    serw.close()
    print("Waiting for 30 seconds to get the fix")
    sleep(30)
except Exception as e: 
    print("Serial port connection failed.")
    print(e)

print("Receiving GPS data\n")
ser = serial.Serial(port, baudrate = 115200, timeout = 0.5,rtscts=True, dsrdtr=True)
while True:
   data = ser.readline().decode('utf-8')
   parseGPS(data)
   sleep(2)

RPi GPS Tracking Using CAT M1

Things used in this project

Hardware components

Software apps and online services

Story

Getting Internet Connection

Commands required for GPS

Turning into Script

Code

gps.py

Credits

Saeed Johar

Comments

Embed the widget on your own site

RPi GPS Tracking Using CAT M1

RPi GPS Tracking Using CAT M1

Things used in this project

Hardware components

Software apps and online services

Story

Getting Internet Connection

Commands required for GPS

Turning into Script

Code

gps.py

Credits

Saeed Johar

Comments

Related channels and tags