Home made GPS localizer

[Vermes]

It is a GPS localizer (transmitter) with additional control functions, which can be used in a car. It consists of GPS receiver HI-204III in version for RS232, a cell phone Siemens S35i and the most important – microcontroller Atmega8 with executive circuits. The microcontroller communicates bidirectionally with the phone modem via hardware UART using AT commands, and the GPS receiver is connected to a software UART, communication is only one way – from the GPS to the microcontroller. Executive circuits are single transistors for small currents and double transistors with MOSFET tips for large currents. Executive circuits are used to feed the mass to the fuel pump and LPG solenoid coil, the ON/OFF key of the phone, the sound alarm, the central locking system (closing). One of the transistors enables supply of the GPS receiver. Control is made by the GPS receiver and the ON/OFF key of the phone. It allows automatic system recovery in case of suspension of the receiver and enabling the phone in case of automatic switch off. Proper operation of this function requires turning on the automatic keys blocking in the phone. 5V supply is carried out by means of 12/5V converter based on LM2575. Applying simple linear stabilizer could cause more load of the accumulator of the car and the need for heat dissipation, because the GPS receiver has a fairly high demand for electricity. The phone has a voltage reduction on data lines on resistor and Zener diode 3V6 in each direction.

This device allows:

• positioning of the car – just call the phone built-in the system from a telephone of an authorized number and the system hangs up the call and sent a SMS with the data – current time, latitude and longitude coordinates, the actual speed of the car)
• giving a signal to the default phone number when the car speed exceeds 20km/h (so you get continuous control over the operation of the system and alert when the car drives away without you)
• giving a signal to the default phone number when the car speed drops below 3 km/h during approximately 2,5 minute, so you can know when the car stops
• sending a SMS of appropriate content to the system may result in:
  • closing the central lock
  • enabling and disabling the alarm
  • enabling and disabling the engine operation lock

The user is informed about the execution of these tasks by the signal back to the default phone number.

Program was written in Bascom.

How it looks inside (the blue element is the GPS receiver):



Phone:



Link to original thread (useful attachment) – Lokalizator GPS i nie tylko