IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676 Volume 4, Issue 6 (Mar. - Apr. 2013), PP 38-42 www.iosrjournals.org www.iosrjournals.org 38 | Page Microcontroller Based Reprogrammable Digital Door Lock Security System by Using Keypad & GSM/CDMA Technology Mohammad Amanullah (Lecturer, Department of Computer Science and Engineering, International Islamic University Chittagong. Bangladesh. Abstract: Now a day’s Security has been a prime concern in the home or office management. Digital door lock security system provides security and safety to house or office owners, belongings, assets from being damaged by external agent or undesired strangers. We have used a new technology, incoming number verification system which gives more protection for controlling & security system. As Conventional security system does not use any password, there is a chance to hack or break the system. In this regard we used a desire mobile number without verification which doesn’t allow the door to be opend.This system is composed of the microcontroller based by using matrix keypad & GSM/CDMA network. The microcontroller based digital door lock security system is an access control system that allows only authorized persons to access restricted area. The password is stored in PROM so that we can change it any time. The system has a matrix keypad .When anyone enter the code in the matrix keypad, microcontroller verify the codes. If that code is correct the device will operate and the door will be open. But if someone enter wrong code a red signal will be shown which means that the entered code is wrong.GSM/CDMA module can be used to operate the device, when anyone make a call from his mobile the receiving device which is set in main circuitry will receive the call. If the call is from desired number then operate the device and the door will be unlocked. An IPS circuit can be used for giving backup in case of emergency when there is a power failure. Keywords: DTMF encoder and decoder, Global System for Mobile Communication, Micro-Controller, Mobile phone, and Matrix Keypad. I. Introduction Tones generated from DTMF keypad can identify what unit we want to control, as well as which unique function we want to perform. A standard 4*4 matrix keyboard can be used support either DP or DTMF modes.DTMF encoder technologies does not require any radiation or any laser beam, not harmful, no limitation of range. It can be used from any distance using a simple telephone line or mobile phone. The UM91214B is a single chip, silicon gate. It provides dialing pulse (DP). IC UM91214B is consists of telephone set which is present in the remote place (Be your workspace) signal are sent through this telephone or mobile. For GSM/CDMA based controlling system, press a button in the telephone set keypad, a connection is made that generates a resultant signal of two tones at the same time. These two tones are taken from row frequency and column frequency. The resultant frequency signal is called “Duel Tone Multiple Frequency “These tone are identical and Unique.MT-8870 operating function include a band split filter that separates the high and low tones of the received pair, and a digital decoder that verifies both the frequency and duration of the received tones before passing the resulting 4-bit code to the output bus.