DTMF based device control

ABSTRACT

Security is prime concern in our day-to-day life. Everyone wants to be as much as secure as to be possible. An access control systems forms a vital link in a security chain. The micro controller based digital lock presented here is an access control system that allows only authorized persons to access appliances. This system is best suitable for corporate offices, ATMs and home security. As a simple example, to lock our mobile phone keypad, a security code of at least 4 digits must be entered.

The system comprises a small electronic unit with a mobile keypad, which is fixed to the electronic circuitry .The devices to be controlled will be selected from his hand held mobile. According to the key pressed at the receiver side the corresponding device will be controlled. A DTMF decoder CM8870C which decodes the keypad signals and these signals are given to the microcontroller.

A buzzer is provided for audio acknowledgment of the key impression. Whenever a key is pressed on the numeric key pad from his handheld numeric keypad, the system acknowledges the impression by a short beep sound. This buzzer is driven by an NPN transistor.

The programming language used for developing the software to the microcontroller is Embedded/Assembly. The KEIL cross compiler is used to edit, compile and debug this program. Here in our application we are using AT89C51 microcontroller which is Flash Programmable IC.AT represents the Atmel Corporation represents CMOS technology is used for designing the IC.

BLOCK DIAGRAM

DTMF based device control

		HARDWARE COMPONENTS 1. Microcontroller 2. MOBILE 3. Uln2003 driver. 4. POWER SUPPLY. 5. Devices 6. buzzer. 7. 16/2 LCD SOFTWARE TOOLS 1. EMBEDDED C 2. KEIL compiler 3. PROTEUS