Microcontroller remote controlling project
-
Upload
bipro-roy -
Category
Technology
-
view
4.250 -
download
3
description
Transcript of Microcontroller remote controlling project
Project Presentation on
DTMF Based Remote Controlling of Home Appliances Using Mobile Phone
ABSTRACT
Aim of the project is to use a mobile phone to control home appliances.
With this project a caller can remotely control home appliances by pressing different keypad buttons which generates identical DTMF signal.
To get desired controlling output using Microcontroller.
Control of home appliances involves 3 different phases
1. Perception2. Processing3. Action
INTRODUCTION
PERCEPTION
First part is the decoding of DTMF tone generated by pressing a key in calling phone.
Audio signal output from receiving phone is fed to DTMF decoder chip.
Decoder chip converts DTMF tone into binary codes to be fed to Microcontroller.
PROCESSING
After perception stage, microcontroller processes the binary codes it receives
Microcontroller is pre-programmed in ”C” to perform specific task according to input bits.
Program is written in AVR Studio and Simulated in Proteus7.7 software.
ACTION
Final stage is to switching ON/OFF the home appliances connected across the main power line of 220 V 50 Hz AC.
For switching purpose electromagnetic Relays were used.
BASIC BLOCK DIAGRAM OF THE PROJECT
Figure 1. Basic block diagram of the project (ref.p-4 )
DTMF- Dual Tone Multi Frequency.
• DTMF is the signal that generates upon pressing an ordinary telephone’s any keypad button.
• Signal generated by the superposition of two pure sinusoidal tones.
• One is high frequency & another is low frequency tone signal.
1 2 3 697
4 5 6 770
7 8 9 852
* 0 # 941
1209 1336 1477 Frequency(Hz)
Each button lies at the intersection of the two tonesTable 1- Row and column frequency correspondence
Structure of 8870 DTMF decoder
Figure 2- Structure of 8870 DTMF decoder (ref. p-6 )
DTMF Decoder 8870Decodes DTMF signals & converts into binary bits
Button Low Frequency(Hz) High Frequency(Hz) Q1 Q2 Q3 Q4
1 697 1209 0 0 0 1
2 697 1336 0 0 1 0
3 697 1477 0 0 1 1
4 770 1209 0 1 0 0
5 770 1336 0 1 0 1
6 770 1477 0 1 1 0
7 852 1209 0 1 1 1
8 852 1336 0 0 0 0
9 852 1477 1 0 0 1
0 941 1209 1 0 1 0
* 941 1336 1 0 1 1
# 941 1477 1 1 0 0
Table 2- Values of decoder output for various frequencies
ATmega 16 Microcontroller Features
High performance, Low power 8 bit Microcontroller.16 KB Flash Memory with read and write capabilities.512 Bytes EEPROM.1 KB Internal RAM.32*8 General purpose working Registers.Three timers.Internal/ External Interrupts.
Working ProcedureThe operation is initiated by calling the second mobile phone at
receiving end.Mobile at receiving end receives the DTMF signals, which is
generated by pressing the keypad of caller mobile phone.DTMF signal is passed to the DTMF decoder IC 8870 and
decodes binary outputs.Binary output is inverted using IC 7404. The inverted output is fed to the input PORT A of the
Microcontroller.The Microcontroller then gives desired output as it was
programmed.When any output pin of PORT D becomes high then connected
corresponding Relay become active and it makes the circuit close to switch ON any circuit or Device.
Number pressed by
user
Output of DTMF decoder
Input to microcontroller
Output from microcontroller
Action performed
2 0x020010
0x0D1101
0x0000000000
Both relays off
4 0x040100
0x0B1011
0x0100000001
One relay on
6 0x060110
0x091001
0x0200000010
Another relay on
8 0x081000
0x070111
0x0300000011
Both relays on
Table 3-Actions performed corresponding to the key pressed
• Microcontroller program was written in C language on AVR Studio.• Program was converted into desired Hex file using AVR Studio.• Circuit was simulated in Proteus 7.7 Software
Simulation circuit is given in Figure 3
Figure 3 – Simulation circuit using Proteus 7.7 (ref. p-13)
MAIN CIRCUIT DIAGRAM
Figure 4- Main circuit diagram (ref. p-15)
RELAY
Relay is an electromagnetic switch.It consists of a control coil and a load circuit. Control coil controls the operation and load circuit is a
switch.Current flowing through the control coil creates a small
magnetic field causes the load circuit switch to close and relay is then active.
Figure 5- Structural view of Relay.
Microcontroller output pin PD0 and PD1 are connected with relays through BC 547 transistor.
When transistor becomes ON then relay also be active.
A relay used as a switch of the home appliance which is connected across the main power supply 220 V- 50 Hz AC.
Here two 220V – 10 W bulbs are used as home appliances.
APPLICATION
The system can be used in controlling home appliances.Can be used in office, lab ,class and factory etc.
This setup with a little modification can be adapted to the following applications
1) Combination Lock2) Home Security System3) Mobile / Wireless Robot control4) Wireless Radio Control5) Continuous monitoring of system status