Dtmf based home automation system using microcontroller ppt
- 2. Contents Introduction to Embedded system Application areas Home Automation System Circuit Diagram Pin Diagram Working operation Advantages Limitations Conclusion
- 3. A combination of hardware and software which together form a component of a larger machine. An example of an embedded system is a microprocessor that controls an automobile engine. An embedded system is designed to run on its own without human intervention, and may be required to respond to events in real time.
- 4. •TV • Stereo • Remote control • Phone / mobile phone • Refrigerator • Microwave • Washing machine Applications
- 5. Real time application(DTMF based device controlling system) DTMF is acronym for Dual Tone Multi Frequency When a button is pressed in your mobile keypad, it will generate a tone of two frequencies. These tones are called row and column frequencies. Generally, row frequencies are low frequencies and column frequencies are high frequencies.
- 7. DTMF Controlled Home Appliances Circuit Principle: The main principle of this circuit is to control appliances like light and fan using DTMF technology. DTMF encoder is present in your mobile and decoder is HT9107B IC. Mobile jack is connected at 1nf capacitor. Mobile jack consists of two wires (Red and black). Red wire is connected to the decoder IC and Black is grounded. When a button is pressed from mobile it generates a tone which is decoded by the decoder IC and it is sent to ATMEGA8 controller. Controller then checks for input and it produces the output according to the code written to it.
- 8. Home Automation System Circuit Diagram: DTMF Based Home Automation System using Microcontroller Circuit Diagram
- 9. Circuit Components: This circuit mainly consists of the following components. •ATmega8 microcontroller U1 •HT9107B IC •Relay •AC Load •Resistors – R1, R2 and R3 •Capacitors – C1, C2, C3 and C4 •Crystal Oscillator X1
- 10. Circuit Diagram
- 11. DTMF (Dual Tone Multi Frequency) decoder Circuit schematic using M8870 • This DTMF (Dual tone multi frequency) decoder circuit identifies the tone from the telephone line and decodes the key pressed on the remote telephone. • Here for the detection of DTMF signaling , we are using the MT8870DE which is a touch tone decoder IC. • The decoded bits can be interfaced to a microcontroller for further application(for example , Remote control of home/office electrical appliances using a telephone network , cell phone controlled home appliances.etc..)
- 12. Table showing DTMF Low and High frequency tones and decoded output
- 13. pin digram of 89s52
- 14. Features • Compatible with MCS®-51 Products • 8K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 10,000 Write/Erase Cycles • 4.0V to 5.5V Operating Range • Fully Static Operation: 0 Hz to 33 MHz • Three-level Program Memory Lock • 256 x 8-bit Internal RAM
- 15. How to Operate the Circuit? When the circuit is powered, controller continuously checks the inputs. When ‘1’ is pressed from mobile keypad, decoder IC decodes the tone and produces 1(0001), it is given to microcontroller which in turn produces high output at PD0 pin. PD0 is connected to relay. Relay is used for switching the circuit and thus fan is ON. Similarly, if the received input is 2 fan is switched off. If received input is 3 light is switched on and if it is 4, light is off.
- 16. Advantages of DTMF Controlled Home Automation System Circuit: •One can control home appliances from anywhere. •It reduces wastage of electricity when we forgot to switch off the lights & fans and gone outside. •It is very low cost compared to other technologies like GSM.
- 17. Limitations of DTMF Controlled Home Appliances: •Synchronization •Number of appliances is limited as our mobile can generate only 16 tones.
- 18. CONCLUSION The DTMF based home appliances provide world wide remote switching operarions.