A simple GPS vehicle tracking system

component

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1. GPS receiver (garmin gps 35), which provides location information of the vehicle

2.gsm module (siemens tc35) for sending sms (text information) to a preset mobile phone

3.ibutton (ds1990a), used to verify that the driver is authorized to use the vehicle

4. Parallax's bs2p control module, connected to a basic stamp development board ().

5. Software:

Epd-v2-01-3e.bps: basic stamp main program

1wire-id.bsp: read ds1990a ibutton serial number subroutine

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Block diagram

The information provided by the gps receiver is output in the "nmea" format (nmea is the abbreviation of the National Marine Electronics Association), and the latitude and longitude information is extracted from the $gprmc sentence, (by format: "Northern lating abc", "Western def" output ).

The gsm module sends the sms information (text information) to the preset mobile phone.

The ds1990a ibutton (the so-called "serial number ibutton") is used for authentication or "key". It contains a globally unique 6-byte long identification number and a 2-byte long crc

Check code. The serial number is of the "read-only" type, and one system can be equipped with two ibutton keys, one of which is reserved or provided to the second authorized driver. Of course, it is also convenient to equip more keys.

Second, the working principle

During the system startup process, the basic stamp continuously scans and detects:

· Is the ibutton inserted into the input?

· Does the car igniter work?

In order for the car to work properly, the authorized ibutton of the car must be inserted into the read/write port, and then the car will start within the set 25 seconds.

An illegal intrusion is considered if:

· The car igniter has been detected to work, and the legal ibutton has not started the car within the required 25 seconds.

· If no ibutton is connected to the system within 25 seconds after the car is started, it is also considered illegal.

Once it is determined that an illegal intrusion has occurred, the basic stamp begins to query information from the gps receiver. Wait for the $gprmc message to appear on the serial output port of the gps receiver.

• bs2p sends the sms information, including the information extracted from the gprmc text received from gps, to a pre-set mobile phone.

· Repeat the process every 2 minutes to let the owner know the location of the vehicle at all times.

Third, system integration

At the heart of the design is a basic stamp that combines the gps receiver, gsm modem, ibutton, and car igniter detection to form a complete system.

The ignition wire is used to detect if the car is being fired. Of course, other indicators (such as ultrasonic sensors or other anti-intrusion detectors) can be used.

· The gps receiver output is connected to p0 of the basic stamp.

• The input to the gsm receiver module is connected to the sout or pin 1 of the basic stamp.

• The p1 pin of the basic stamp is connected to the igniter, and a high level indicates that the igniter is operating and vice versa.

· p15 is used to interface with the ibutton.

Need to be reminded that the bs2p in the basic stamp series supports ibutton's 1-wire bus interface protocol, which was not supported by earlier products.

Log in to your mobile phone number

You can program the mobile phone number as follows:

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Debug "+44********** " enter the destination mobile phone number here

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The input number must be in the following format:

+ Country code (44 in the example above represents the UK code) + Personal mobile phone number.

This number will be the destination number for the system to send management information, including the location information of the vehicle.

Login ibutton serial number:

Enter the ibutton serial number to be used. If only one ibutton is used in the system, the number needs to be repeatedly written to the memory reserved for the alternate ibutton.

The ibutton code is written as shown in the following program. In this example, the ibutton code used in the example has been entered into the system. When actually writing the code, please replace the number after the "$" symbol in the sample program with the code of the specific ibutton. The serial number is expressed in hexadecimal.

A separate subroutine can be used to display the serial number of the specified ibutton, which is logged into the final program code and downloaded to the basic stamp processor.

.

"Log in the first ibutton serial number:"

If romdata(0) <> $03 then checksecond first byte

If romdata(1) <> $f0 then checksecond

If romdata(2) <> $bc then checksecond

If romdata(3) <> $08 then checksecond

If romdata(4) <> $10 then checksecond

If romdata(5) <> $00 then checksecond

If romdata(6) <> $00 then checksecond

If romdata(7) <> $30 then checksecond eighth byte

Goto buttonok

Checksecond:

"Log in to the second or remaining ibutton serial number:"

If romdata(0) <> $01 then badbutton first byte

If romdata(1) <> $68 then badbutton

If romdata(2) <> $21 then

Badbutton

If romdata(3) <> $24 then badbutton

If romdata(4) <> $08 then badbutton

If romdata(5) <> $00 then badbutton

If romdata(6) <> $00 then badbutton

If romdata(7) <> $31 then badbutton eighth byte

Track the car after completing the above changes.

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