SYSTEM DESCRIPTION

The entire Vehicle Monitoring and Security System is built around the PIC 18F8722 IC. It consists of 5 units comprising of

1. A Keyboard Unit
2. An LCD Unit
3. An RF Unit
4. A GPS Unit
5. A GSM Unit

Each unit in the Vehicle Monitoring and Security System undertakes a specific job and can be explained as follows:

• The keyboard unit is used to type in the password and other information that needs to be keyed in.
• The LCD unit is used to display the information that is keyed into the keyboard and for other menu applications.
• The RF receiver unit is used to provide a unique code about each employee/passenger and for security applications.
• The GPS module containing the GPS antenna receives the information from the GPS satellite in NMEA format.
• The GSM module transfers the information got by the GPS receiver to the Base Station. The Base Station decodes the information to the required form.

THE KEYBOARD UNIT:

The keyboard is organized as a matrix of 4 rows and 3 columns. The columns are connected to an output port and the rows are connected to an input port. In this unit the keyboard is interfaced to the PIC18F722 IC with PORTB as the input port and PORTG as the output port. Pins RB2-RB5 of Port B and pins RG0-RG2 of Port G are connected to the keyboard.

If no key has been pressed, reading the input port will yield 0s for all rows since they are all connected to low (GND). It is the function of the PIC microcontroller to scan the keyboard continuously to detect and identify the key pressed. To identify a pressed key, the PIC microcontroller sends a 1 to each of the columns, starting with the first column; then it reads the rows. If the data read is all 0s, no key in that column is activated and the process is moved to the next column. A high is given to the next row, reads the columns, and checks for any 1’s. This process continues until the row is identified. After the identification of the row in which the key has been pressed, the next task is to find out which column the pressed key belongs to. This should be easy since the microcontroller knows at any time which row and column are being accessed.

THE LCD UNIT:

The LCD that is used in this project is LAMPEX 16101 LCD display, which is a one line 16-character display. The display contains two internal byte-wide registers, one for commands (RS=0) and the second for characters to be displayed. It also contains a user-programmed RAM area (the character RAM) that can be programmed to generate any desired character that can be formed using a dot matrix.

LCD PIN DESCRIPTIONS:
The LCD used for this project has 14 pins. The function of each pin is given in the table below:

LCD INITIALIZATION:

The module automatically performs initialization when powered on (using internal reset circuit).
The following instructions are executed during initialization:

1. CLEAR DISPLAY:  The Busy flag is kept in the Busy state (BF=1).
   Unit initialization ends. The time is 15ms.
2. FUNCTION SET:   DL=1  ; 8-bits long interface data.
   N=0   ; 1 line display.
3. DISPLAY ON/OFF CONTROL:
   D=0    ; display off.
   C=0    ; cursor off.
   B=0    ; blink off.
4. ENTRY MODE SET:
   I/D=1  ; increment (+1) .
   S=0     ; No shift.
5. DDRAM:  DDRAM is selected. Power on initialization depends on rise time of the supply when it is turned on.

When the above power supply condition is not satisfied, the internal reset circuitry doesn’t operate correctly. In this case, perform the needed initialization by sending function set instructions thrice from MPU after turning the power on.

For example, to designate an 8–bit data length, send the following instruction thrice:

When this ends, the module enters 8-bits data length mode without fail, then enters 4-bits data length instruction for 4-bits data length interface.