LITERATURE REVIEW

DEFINITION OF DOOR SECURITY MONITORING SYSTEM


A lock is a mechanical fastening device which may be used on a door, vehicle, or container, restricting access to the area or enclosed property. Commonly, it can be released by using a key, keycard, RFID signal, but for this FYP it comes out with user need to key in the code or password. Besides, it also combines with transmitter, receiver, PIC, magnetic lock, electronic components and programming.

  PIC MICROCONTROLLER 16F877A

Microcontrollers must contain at least two primary components – random access memory (RAM), and an instruction set. RAM is a type of internal logic unit that stores information temporarily. RAM contents disappear when the power is turned off. While RAM is used to hold any kind of data, some RAM is specialized, referred to as registers. The instruction set is a list of all commands and their corresponding functions.Most microcontrollers also contain read-only memory (ROM), programmable read-only memory (PROM), or erasable programmable read-only memory (EPROM). Al1 of these memories are permanent, they retain what is programmed into them even during loss of power. They are used to store the firmware that tells the microcontroller how to operate. They are also used to store permanent lookup tables. Often these memories do not reside in the microcontroller; instead, they are contained in external ICs, and the instructions are fetched as the microcontroller runs. This enables quick and low-cost updates to the firmware by replacing the ROM.

KEYPAD

For keypad wiring, keypads pins need to pull up or pull down to avoid floating case happen. Pull up normally connect to 5V and pull down is connect to ground. 4x4 Keypad pin can directly connect to microcontroller or keypad decoder IC for decodes purpose. However, DIY scanning of keypad consumes a lot of understanding in programming and more program space. The better way to interface a keypad to the PIC is to use a keypad encoder in between the keypad and the microcontroller

TRUTH TABLE KEYPAD ENCODER MMC74C922

Switch Position		0 1 2 3 4 5 Y1,X1 Y1,X2 Y1,X3 Y1,X4 Y2,X1 Y2,X2						6 7 8 9 10 Y2,X3 Y2,X4 Y3,X1 Y3,X2 Y3,X3					11Y3,X4
D
A	A	0	1	0	1	0	1	0	1	0	1	0	1
T	B	0	0	1	1	0	0	1	1	0	0	1	1
A	C	0	0	0	0	1	1	1	1	0	0	0	0
O	D	0	0	0	0	0	0	0	0	1	1	1	1
U	E (Note 1)	0	0	0	0	0	0	0	0	0	0	0	0

Switch Position		12 Y4,X1	13 Y4,X2	14 Y4,X3	15 Y4,X4	16 Y5(Note 1), X1	17 Y5 (Note 1), X2	18 Y5 (Note 1), X3	19 Y5 (Note 1), X4
D
A	A	0	1	0	1	0	1	0	1
T	B	0	0	1	1	0	0	1	1
A	C	1	1	1	1	0	0	0	0
O	D	1	1	1	1	0	0	0	0
U	E (Note 1)	0	0	0	0	1	1	1	1