22-03-2012, 04:30 PM
home automation using mobile communication
2-REPORT-dkl.doc (Size: 1.58 MB / Downloads: 59)
INTRODUCTION:
Here is a circuit that lets you operate your home appliances like lights and water pump from your office or any other remote place. So if you forgot to switch off the lights or other appliances while going out, it helps you to turn off the appliance with your cell phone. Your cell phone works as remote control to your home appliances. You can control the desired appliance by presetting the corresponding key. The system also gives you voice acknowledgement of the appliance status.
The Project “Home Automation using mobile communication” has different sections such as:
1. Microcontroller
2. DTMF decoder
3. Voice recording and playback device
CIRCUIT DESCRIPTION
The circuit diagram shows the circuit diagram of home automation using mobile communication. It comprises microcontroller AT89C51, DTMF decoder MT8870, voice recorder and playback device APR9600 and a few discrete components.
Microcontroller AT89C51 is at heart of circuit. It is high performance, low power, 8 bit microcontroller with 4 KB of flash programmable and erasable read only memory used as on-chip program memory, 128 bytes of RAM used as internal data memory, 32 individually programmable input/output(I/O) lines divided into four 8bit ports. A 11.0592MHz crystal (XTAL1) is used to provide basic clock frequency for the microcontroller. Capacitor C3 and resistor R3 from power on reset circuit, while push to on switch S20 is used for manual reset.
The DTMF decoder is used for decoding the mobile signal. It gets DTMF tone from the mobile headset’s speaker pins and decodes it into 4 bit digital signal. The DTMF decoder is operated with a 3.579 MHz crystal (XTAL2). In DTMF receiver MT8870 (IC3), capacitor C12 is used to filter the noise and resistors R6 and R7 help to amplify the input signal using the internal amplifier.
Pin 16 of IC3 connected to resistor R5 provides the early steering output. It goes high immediately when digital algorithm detects a valid tone pair (signal condition). Any momentary loss of signal condition causes ESt to return to low state. Pin 17 of IC3 connected to capacitor C11 is bidirectional, acting as steering input/guard time output (St/GT). A voltage greater than threshold of steering logic VTSt detected at St causes the device to register the detected tone pair. The guard time output resets the external steering time constant, and its state is a function of ESt and voltage.
TESTING RESULTS
Procedure
For testing the circuit, we have to be confirming about the connections and then give the ac supply to the circuit. Then its output is to be measured with the multimeter and the wave is to be visualized in the oscilloscope.
Results & Conclusion
1. The Cell Phone Operated Watering System or GSM module is remotely controlled by any mobile. When mobile number of GSM module is called by other any mobile, then it will automatically receive the call due to auto answering
mode. Upon pressing a number in mobile, DTMF tones will be generated in mobile of GSM
module. This DTMF signal is again decoded and given to microcontroller which is finally
actuating a relay drive to control single phase AC submergible Pump.
2. Automated Garden Lamp is an arrangement where lamps of the garden will be ON only in
night and automatically switched off in day light. This circuit is built based on a light
sensor as LDR (light dependent resistor).
3. Security system contains person detector circuit, Voice Recorder & Playback circuit and
Digital codes lock circuit for garden gate which is verified by taking a demo module.