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Home Automation Using DTMF Decoder


Published on Nov 30, 2023

Introduction

In this project we present a home automation system using telephone lines. The system consists of two subsystems. One is the remote control system. The other one is the phone monitoring system. The remote control system use the dual tone multi-frequency signals to control the operations of various appliances. The hardware and software are designed based on the standard telephone system. The phone monitoring system provides convenient services for the user to better monitor the usage of their phones.

In Home automation system, first we dial our programmed standard telephone system from any landline or mobile telephone that would ask for PIN number for secure transaction. After authentication, the telephone would wait for a number to be entered from the user and according to the entered number , it would generate a dual tone multi-frequency signal.

According to this signal DTMF decoder CM8870 decodes the signal & converts it into a 4 bit number in Q1 to Q4 and transmits it to the PIC16F877 Controller. The PIC controller would interpret the signal from the DTMF decoder and control the device using relays. So, that we can control 4 devices sitting at a remote place.

Remote control system by telephone presented in this project is based on PIC and has very secure structure. Designed circuit is isolated both optically and electrically; therefore it does not create any effect on telephone line. With pin-check system, non-authorized people can not connect to or use this system. In this application, secure cheap and safe remote control system for intelligent houses has been presented

The system consists of two subsystems. One is the remote control system. The other one is the phone monitoring system. The remote control system use the dual tone multi-frequency signals to control the operations of various appliances. The hardware and software are designed based on the standard telephone system. The phone monitoring system provides convenient services for the user to better monitor the usage of their phones.

• As shown in the block diagram of Home automation system, first we dial our programmed standard telephone system from any landline or mobile telephone that would ask for PIN number for secure transaction.

• After authentication, the telephone would wait for a number to be entered from the user and according to the entered number, it would generate a dual tone multi-frequency signal.

• According to this signal DTMF decoder CM8870 decodes the signal & converts it into a 4 bit number in Q1 to Q4 and transmits it to the PIC16F877 processor.

• The PIC controller would interpret the signal from the DTMF decoder and control the device using relays. So , that we can control many devices sitting at a remote place.

Applications:

• We can turn on devices like lamps, oven , water heater , room heater, computer while sitting at a remote place or while reaching to home

• Cameras to monitor home:

???See who is at the front gate or front door,???Monitor all outdoor areas, Deter burglars from home.

• Networking:

Have a very high speed wired network among multiple rooms of home.

Have wireless access throughout home.

Access your home remotely (hotel or office) while securely blocking others.

• The automatic or semi-automatic control of lighting

• Water:

Automatically turn the hot water recirculation,

On 10 minutes before your wake up alarm.

Off when you go on vacation