GPS(L80R)-GSM(A6) GPRS/SMS REAL TIME TRACKER WITH REMOTE SMS CONTROL AND CONTROL OUTPUT

This is a new GPS-GSM tracker based on my previous designs. The tracker has many similarities and some major improvements. Now it can be used not only for tracking with SMS messages but also in real-time through GPRS data communication.

– The power supply input is limited from 3.3v to 4.1v – i.e. a standard Li-Po battery
– 1Mb built in memory enough for 1 hour tracking data
– SIM card holder is mini-SIM size
– Schematic is a bit simplified
– Size is 60x20mm
– Quectel L80 GPS module
– Ai-Thinker A6 GPRS module
– 50mA nominal consumption
– 700mA peak current consumption when connecting to the network or receiving/sending messages
– One 25mA logic output for control
– USB port for PC communication
– LiPo battery charger over USB
– 20gr weight
– Total cost of the BOM ~17$

Functionally the tracker has the following capabilities:
– Receiving commands via SMS text commands
– Sending periodic status messages
– Calculating the current distance and bearing from the start point i.e. 205m North-East
– Sending an automatic status message when a predetermined distance in any direction from the start point has been reached
– Real-time tracking in Google Earth via GPRS data
– Bootloader for easy Firmware update
– Signal strength monitoring
– Battery level monitoring

COMMANDS OVER SMS

In this design I added some additional commands that can be sent via SMS. The tracker will accept the following SMS commands:

UIP IP; –> Update IP address. Example UIP 215.60.38.125;
ON1 –> Turn on output
OF1 –> Turn off output
SMS –> Sends SMS with the current coordinates to the preset number for periodic messages
STN –> Send to This Number, sends SMS with the current coordinates to this number
UPN –> Update Phone Number for periodic messages with this number
OFS –> Off SMS, stops periodic SMS
GON –> GPRS On, start a GPRS connection (if not started by default)
GOF –> GPRS Off, stops GPRS connection

MESSAGE CONTENT

Each message contains the following information:
– Last valid Latitude
– Last valid Longitude
– Last valid altitude
– Current fix status i.e. valid or not valid
– Distance from the starting point
– Bearing from destination point
– What triggered the message
– Signal strength
– Battery voltage
– Link with the current coordinates for Google maps (thanks to apakhom for the suggestion)

APPLICATION MENUS

* Before you can start using the main GPS-GSM tracker application, you need to install the Visual Basic 6.0 Runtime Libraries – compact installation is sufficient.

A: SETTINGS
– Each output can be separately set up when enabled by message to switch on only once, once every 15,30,60 and 120 seconds or continuously
– Each output can be set up how long to stay switched on – from 0.1sec to 5.0 seconds
– The SMS destination phone number
– How often the SMS messages to be send – from 10 to 65000 seconds
– The SMS center phone number (not so often used nowadays, depends on the provider)
– Border radius in meters in any direction from the start point, which if crossed, an automatic status message will be send
– How often the current coordinates should be written in the memory (1sec to 65000 seconds). If the coordinates are written every second, then the memory is enough for about an hour
– Data mode – either GPRS or SMS
– GPRS APN
– GPRS User ID
– GPRS Password
– Destination IP address
– Destination port to use

B: DOWNLOAD
– Download the trip record from memory

C: REAL TIME 1
– The current GPS coordinates are decoded and transmitted in real time in short format i.e. Latitude, Longitude and Altitude only.

D: SAVE FILE
– Save the current information in the text box to a text file

E: SERVER
– Start a TCP server – it is necessary to start a TCP server in order to receive GPRS data

F: FORMAT MEM.
– Delete memory. There’s no real need to clear it before each trip as old data will be overwritten.

G: REAL TIME 2
– The current GPS information is transferred in real time without any post processing

H: OPEN FILE
– Open file with GPS data for display

REAL-TIME TRACKING OVER GPRS

– First set up the GPRS function:
— GPRS APN – this is the GPRS Access Point Name for your cellular network
— GPRS USER ID – see if required for your cellular network
— PASSWORD – see if required for your cellular network
— IP ADDRESS – this is your public (not local) IP address
— PORT – listening port
* If you are using a Wi-Fi router you will have to set up a port-forwarding for the given port to your local IP address

– Second start a local TCP server
— select SERVER option and confirm to create a Network Link
— enter the same listening port as in the settings
— click START to start a TCP server

-Third set up Google Earth
— start Google Earth
— go to Add –> Network Link
— copy the path for the newly created Network Link from GPS-GSM TRACKING application
— paste the path in Google Earth at the Link box
— go to Refresh and change “Time-based Refresh” to “Periodically – 1sec”
— select “Fly to View on Refresh”

This is the basic set-up but you can further experiment with the other GE settings.

FIRMWARE UPDATE OVER USB

In this new modification of the GPS-GSM TRACKER I have provided the option to update the firmware over USB. For this purpose I’ve written an USB Bootloader for the PIC18F26J50 Microcontroller and made a special FIRMWARE UPDATE APPLICATION. Basically you flash the PIC18F26J50 with the Bootloader firmware using the ICSP port and then using the provided application you can flash and update the main firmware.

– Start the FIRMWARE UPDATE TOOL
– Connect to USB
– Start the tracker
– Select the new firmware file and flash it in the memory

GPS-GSM TRACKER v4.1 schematic is very simple:

PROJECT FILES:

GPS_GSM_TRACKING – CADCAM

GPS_GSM_TRACKING_V4_1_FIRMWARE_1.03
GPS GSM USB_BOOTLOADER_FIRMWARE 1.01

GPS_GSM_TRACKING_MAIN_APP 1.4
GPS_GSM_TRACKING_BOOTLOADER_APP 1.02