Global positioning system (GPS) is a wonderful technology that has made navigation systems highly accurate and efficient in recent years. All the mobile phones these days come with an in-built GPS receiver through which you can easily find out your current location anywhere on the earth. The only thing required is an unobstructed line-of-sight to four or more GPS satellites.
A GPS navigational device is any device that receives GPS signals and processes them to extract information for determining its exact location. Presented here is such a GPS device with a tracking record system. It shows the path traversed by you from the initial position, so you are never lost at unknown locations and can always come back to the initial point.
Circuit and working
Fig. 2 shows circuit of the GPS navigator. The circuit is built around microcontroller ATmega16 (IC1), 5V voltage regulator 7805 (IC2), GPS module (connected at CON1), graphical LCD (GLCD1) and a few other components.
The circuit is powered by a 9V/12V adaptor. Regulator IC2 provides 5V regulated supply for the circuit to operate. LED1 indicates presence of power in the circuit.
Microcontroller IC1 running at a clock frequency of 16 MHz communicates with the GPS receiver modem via serial protocol. Tx pin of the GPS receiver is connected to Rx (PD0) pin of microcontroller IC1. The GPS receiver continuously transmits data at 1Hz update rate.
A 128×64-pixel, KS0108-controller-based GLCD is used to display the navigation data. Port pins PB0 through PB7 of IC1 are connected to data pins D0 through D7 of GLCD1. Port pins PD2 through PD6 are used to provide control signals RS, R/W, EN, CS1 and CS2 to GLCD1, respectively. Switch S1 is used to reset the navigator.