Microcontroller based Intelligent Digital Volume Controller with Timer
Contents
1. SET USB TO SERIAL CONVERTER 10 OPTOCOUPLER VOLTAGE DIVIDER FOR RIGHT AUDIO CHANNEL VOLTAGE DIVIDER FOR LEFT AUDIO CHANNEL MICRO CONTROLLER AT89S352 ANALOGUE SWITCH CD4066 PAIR FOR LEFT CHANNEL ANALOGUE SWITCH CD4066 PAIR FOR RIGHT CHANNEL LOW LOW SET TEL BREAK POWER SWITCH POWER LED VOLUME UP VOLUME DOWN SEVEN SEGMENT DISPLAY Fig 14 Microcontroller Based Intelligent Digital Volume Controller with Timer Top View 262. International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 Microcontroller based Intelligent Digital Volume Controller with Timer Diptarup Paul Department of Computer Science and Engineering JIS College of Engineering Kalyani Nadia 741235 West Bengal India ABSTRACT In this paper a Microcontroller based intelligent digital volume controller is presented to control music system and PC speaker volume digitally and change volume levels automatically in case of certain predefined incidents such as incoming or outgoing telephone call and pre set alarm The device is constructed with AT89S52 microcontroller from ATMEL family with 8051 architecture and its software program being written in C language Keywords Microcontroller AT89S52 CD4066 optocoupler Zener diode Seven segment display voltage divider 1 INTRODUCTION The project is aimed at being a regular household product This not only has a digitalized volume control mechanism of music system but also includes intelligent decision making to change the volume level for certain incidents For how many times we have faced inconvenience to attend a phone call when music is playing loud in our room Well this device brings the solution It automatically tracks the telephone line and detects an incoming call and brings down the volume to a much lower definable level Same thing happens for outgoing calls too And yes this can be done manually
3. THE COMMUNICATION IF TELEPHONE QNDITION IS fe YES NITIATE A VOLUME LEVEL COUNTER AT A DEFAULT VALUE SWITCH VOLUME LEVEL TO THE VALUE SET IN VARIABLE TEL International Journal of Computer A lications 0975 8887 Volume 38 No 1 January 2012 YES TEL BREAK KEY NO NO DISABLE TELEPHONE YES IGNORE AND SWITCH SYSTEM VOLUME TO LEVEL TEL ENABLE TELEPHONE IGNORE AND SWITCH SYSTEM VOLUME BACK TO NORMAL TELEPHONE LINE NOT IN USE DISABLE TELEPHONE IGNORE AND SWITCH SYSTEM VOLUME BACK TO NORMAL CHECK TIME TRIGGER YES FROM COMPUTER THROUGH SERIAL COMMAND CHECK YES IF PRESENT VOLUME IS LOW NO SWITCH VOLUME LEVEL TO THE SWITCH VALUE SET IN LEVEL VARIABLE LOW WHERE IT DISPLAY VOLUME LEVEL IN THE 7 SEGMENT IN NORMAL CONDITION TOGGLE Dp LED AND VOLUME LEVEL IN LOW VOLUME CONDITION TOGGLE g LED AND VOLUME LEVEL IN TELEPHONE ACTIVE CONDITION SEND PRESENT VOLUME LEVEL OF THE SYSTEM TO COMPUTER THROUGH SERIAL GOTO BEGINING OF THE LOOP Fig 11 Flow Chart 24 5 FUTURE SCOPE AND CONCLUSION Following enhancements can be made individually on the hardware part and the software part as follows Hardware In this device the timer thing is implemented in the software part and the volume change is being performed in the hardware The implementation of a hardware clock
4. as well The device also contains a clock implemented with computer software by which we can set an alarm and also set different volume levels for a particular time of the day That means an alarm clock but with a brain For example Let the time be set at 10 PM in the clock the clock is there to decrease the volume at 10 PM without ones interference keeping one busy on what one is up to In case a user wants to use this device with his computer speaker system there is an option for him to manage the alarm system from the computer itself Yes This device can be controlled from the computer by the means of serial communication 2 BASIC TERMINOLOGY A micro controller is a small computer on a single integrated circuit containing a processor core memory and programmable input output peripherals where peripherals can be any electronic device As the name suggests the device is controlled by a microcontroller AT89S52 1 from Atmel Corporation AT89S52 1 see Figure 1 is a 40 pin low power high performance 8 bit microcontroller with 8 kilo bytes of in system programmable Flash memory 256 bytes of Random Access Memory 32 I O lines Watchdog timer two data Sukalyan Som Department of Computer Science Barrackpore Rastraguru Surendranath College 85 Middle Road amp 6 Riverside Road Kolkata 120 pointers three 16 bit timer counters a six vector two level interrupt architecture a full duplex serial port on chi
5. attached to this device can make this thing work independently In that clock alarm time can be set by the user and the sound level will go down accordingly The clock can act as an alarm clock too on implementing a separate buzzer with it Further implementation of an IR remote with this device can make it more efficient and help the user to control the device from a distance The volume level a user sets in the system gets reset once the device is restarted Implementing a memory i e an EEPROM with the device can solve the problem Software The software that helps the user to interact with the hardware can be made provided with more features such as a countdown timer which will also help in the alarm operation A reminder facility to notify the user about his scheduled works can be implemented A stopwatch can also be implemented along with the software Provisions of setting an alarm with date and not only time can be implemented further This system came up as a need to a guy who is a music freak and is clumsy with his stuffs In this project microcontroller based intelligent digital volume controller with timer we designed a hardware that is capable of controlling volume of any audio system and is also capable of switching volume levels during incoming or outgoing phone calls in wired network The microcontroller programming is performed in Embedded C Each and every operation in this device is made interactive and easy to recog
6. ed The volume level and other options are being displayed in a 7 segment display Seven segment displays are widely used in digital clocks electronic meters and other electronic devices for displaying numerical information It contains 7 LEDs arranged in such a manner that when illuminated accordingly can display numerical digits It is of two types common anode and common cathode The schematic of a 7 segment display is shown in Figure 5 Common anode 7 segment display is used in this project International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 Common Cathode Common Anode a Gnd a ob g f Wee a 65 Fig 5 Schematic view of a 7 segment display The volume levels are defined by the help of series voltage dividers In electronics a voltage divider also known as a potential divider is a simple linear circuit that produces an output voltage Vow that is a fraction of its input voltage V Voltage division refers to the partitioning of a voltage among the components of the divider 6 Figure 6 is a representation of a voltage divider Vi Z1 Veit 23 Fig 6 Voltage divider 3 PROPOSED LAYOUT 3 1 Idea about the project The purpose of this project is to develop a digital volume controlling device that is capable of controlling the volume of a music system and PC speaker system to a predefined volume level when the user is receiving a phone call in his land phone There w
7. el to LOW The functionality of the button is same as that of the LOW key in the hardware Current time It shows the system time in 24 hour format from the computer Present Volume Level This shows the volume level the hardware is set to It is volume level which is being displayed in the 7 segment display in the hardware Set Alarm Time This is the text area where the user is required to type in the time in hour minute and second in HH MM SS format Set Alarm This button sets the time entered in the text areas of Set Alarm Time If any of the text boxes are left as blank by the user then it takes default value as 0 At this particular time the device will switch itself to LOW state and vice versa provided the device has to remain connected to computer 23 INITIATE DEVICE WITH DEFAULT VALUES AT INPUT AND OUTPUT PINS OF THE MICROCONTROLLER INTIATE SERIAL COMMUNICATION KEPT LOOP BEGIN NO CHECK KEYPAD FOR INPUT AND SERIAL PORT FOR DATA COMMAND TO INCREASE VOLUME OR VOLUME UP YES COMMAND TO YES SET LOW LEVEL OR 477777 OW SET KE STORE PRESENT VOLUME VOLUME BACK TO COUNTER VALUE IN A NO VARIABLE LOW WAS YES STORE PRESENT VOLUME COUNTER VALUE IN A VARIABLE TEL DISPLAY COMMAND TO MUTE OR LOW IF PRESENT VOLUME IS SWITCH VOLUME SWITCH VOLUME LEVEL TO THE LEVEL BACK TO VALUE SET IN WHERE IT WAS VARIABLE LOW
8. esentation of sound level switching is shown in the above figure see Figure 8 Where Ly is the mute condition and L is the highest volume level R Ro R3 R are resistors of equal value In this project eight resistors are being used against each of channel left and right To get 8 1 1 e 9 distinct sound levels 3 4 Circuital implementation and control description The working model of the device is made a quite user friendly The circuit diagram is shown in Figure 9 Switches S1 to S6 are configured as VOLUME UP VOLUME DOWN LOW LOW SET TEL VOL and TEL BREAK respectively VOLUME UP key is programmed to increase the volume of the system as because this system comes with a built in volume controller VOLUME DOWN key is programmed to decrease the volume of the system TEL VOL key is programmed to set the volume of the speaker system i e the volume level that the speaker system will be playing in when the telephone is in use It can be 0 i e mute or any level user wants it to be LOW SET is to set the volume level of the LOW button operation if in this case the volume level is set to 0 it can act as mute button depending upon the user s will TEL BREAK button is to bypass the telephone interfacing If when the music is silenced by the device and the user wants to resume it to the volume it was playing pressing this button will bypass the silenced condition till the end of the call A telephone interfac
9. evel being shown in the 7 segment display while the telephone line is not being used This volume level is now set to be used during the call To denote the land phone call state the 7 Segment Display alternately glows g LED and the set level In case of parallel connection in ones home the telephone interference can be bypassed by pressing the TEL BREAK key which resets itself with the end of the call The telephone interference can be recalled by pressing the TEL BREAK button again while the telephone line is being used This device can be operated from the PC itself and in that case the PC can act as the timer In this case one can set 22 AUDIO LINE OUT the time to either increase or decrease the volume to the level set by the LOW SET button The device runs on 5 volts DC To power this device one can use a DC adaptor ranging from 6 to 15 volts The voltage is stepped down to 5 volts be the use of a voltage regulating IC LM317 Fig 10 LM317 voltage regulation block diagram In the above diagram Figure 10 voltage regulating implementation with IC LM317 is shown which is used to generate 5 voltage for the circuit Here R1 is 220 ohms R2 is B Volume timer Current time 73 15 37 International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 100 ohms and R3 is 560 ohms Vix can be any voltage between 6V to 15V VOUT is 5V The datasheet of LM317 11 and onli
10. ft info timer software html 10 AVR CDC http www recursion jp avrcdc 11 LM317 Datasheet http www ti com lit ds symlink Im117 pdf 12 LM 317 Calculator lab com articles LM3 17 http www electronics 8 ABOUT THE AUTHORS Diptarup Paul is presently working as a Hardware and Embedded System Research and Development Engineer in Security Engineers Private Limited West Bengal India He has received his B Tech in Computer Science from West Bengal University of Technology West Bengal India His research interest includes Cryptography Steganography Microcontroller and Microprocessor Biometric Sensors RFID Sukalyan Som is presently working as an Assistant Professor in Computer Science in Barrackpore Rastraguru Surendranath College West Bengal India He is having over 5 years of teaching experience He has received his B Sc in Statistics from University of Calcutta West Bengal India and Masters in Computer Application from West Bengal University of Technology West Bengal India His research interest includes Cryptography Steganography Image Processing Computational Geometry etc 25 International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 VOLTAGE REGULATOR LM317 POWER SOCKET FEMALE TELEPHONE LINE CONNECTOR RJ 11 AUDIO CONNECTOR FEMALE STEREO VARIABLE RESISTANCE AUDIO INPUT CHANNEL SETREO 13V ZENER DIODE BRIDGE RECTIFIER AUDIO BYPASS DPDT TEL
11. ill be provision for the user to control the device from the computer if he wants to Moreover the user will be given a option to adjust the volume to a predefined level at a particular time of the day by the clock implemented in the computer software provided along with the device 3 2 Presently available options Presently available volume controllers with timer are mainly software based i e they are usable in a computer only and no hardware implementable volume controller with telephone based intelligence is available For example Alarm 7 Cool Timer 8 Timeleft 9 etc The existing softwares mentioned here have the following generic features a They act as a reminder on an oncoming event b Tracks the amount of time left for specified event c They are capable of being a countdown timer and sound an alarm when the alarm goes off Existing softwares provide alarm facility by means of software and are meant explicitly for PC use The volume levels cannot be controlled automatically by the softwares users choice 20 Thus it can be cited that this device has the following edge over the existing systems and or software a This is a general purpose digital volume controller for both music system and PC b Itis an attempt to combine volume control with alarm by the means of hardware c Itis anovel attempt that includes automatic volume level changes in case of special incidents such as incoming telephone call and al
12. ing female socket RJ11 is attached to the telephone input part of the circuit Audio sockets are attached at LINE IN and LINE OUT S7 is a DPDT switch to bypass the audio line from the circuit A USB to Serial converter 10 connected to this device for serial communication with a computer The functional description in other words the user manual to operate the system is stated as follows a A telephone interfacing female socket RJ11 is attached to the telephone input part of the circuit b Audio sockets are attached at LINE IN and LINE OUT S7 is a DPDT switch to bypass the audio line from the circuit A USB to Serial converter 10 connected to this device for serial communication with a computer 21 g 16 K R17 Waaka kapa aee Fa Ve be qqidaaad ver t gt p Bo hd ha er 3 o Fal pt 20 F let EK OA VCC 59 POWERLED Fie GND 7 International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 120 ohms 120 ohms Ri 120 ohms 120 ohms Fig 9 Circuit Diagram The device is connected to PC or any audio device and the speakers are connected to this device Telephone line is connected to the RJ 11 socket in parallel to the main telephone line Audio input is taken and set in to the voltage divider created by resistances in series From every point in the voltage divider ladder output is taken The outputs a
13. ne calculator 12 has been consulted for the values of R1 R2 and R3 3 5 Flow chart The flow chart follows in Figure 11 4 SOFTWARE INTERFACE This device comes with a computer software This interface has been developed with Microsoft Visual Basic 6 0 This software is optional to a user The privilege a user gets while using this software is that he gets the option to set timer to control the device This timer helps him to switch the device to LOW volume level i e the operation he gets by pressing the LOW key in the hardware But in this case the software is there to make him lazy The only thing he has to do is to plug the device to his computer USB port run this software and set the time The software will do the rest The following figure see Figure 12 shows a screen shot of the software in action Present Volume Levek 7 Hr 24 Min Sec Set Alarm Time Fig 12 Software interface The functionality of each button of the software is stated as follows Volume This button will increase the volume level in the device by level 1 the same way the VOLUME UP key acts in the hardware device Volume This button will decrease the volume level in the device be level 1 the same way the VOLUME DOWN key acts in the hardware device Set low Thus button will set the volume level of the low volume level same as LOW SET in the hardware Decrease now This button will decrease the volume lev
14. nize The device surrenders itself to its user s will in case of volume levels The computer software is designed in such a way that it can be easily operated 6 ACKNOWLEDGMENTS The authors express a deep sense of gratitude to the Department of Computer Science JIS College of Engineering Kalyani Nadia 741235 West Bengal India and Department of Computer Science Barrackpore Rastraguru Surendranath College Kolkata 700 120 West Bengal India for providing necessary support for the work and their family members for being constant inspiration and motivation for pursuing such works International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 7 REFERENCES 1 AT89S52 Datasheet http www atmel com dyn resources prod_documents doc1919 pdf 2 CD4066 Datasheet http members shaw ca roma 4066 pdf 3 Opto Isolator http en wikipedia org wiki Opto isolator 4 Zener Diode http en wikipedia org wiki Zener diode 5 D Chattopadhyay P C Rakshit New Age International Publication Electronics Fundamentals and Applications p 72 6 Voltage divider Or Potential divider http en wikipedia org wiki Voltage divider 7 Alarm amp Clock software from CNET http download cnet com Alarm 3000 2350 4 10742679 html tag main dropDownForm 8 Cool Timer from Harmony Hollow software http www harmonyhollow net cool_timer shtml 9 Time Left 1S a timer Software http www timele
15. p oscillator and clock circuitry T2 FP 1 0 1 40 I VEE T2 EX P1 10 2 39 D P0 0 ADO P1i 203 38 1P0 1 AD1 P1 3C4 37 1P0 2 AD2 P1405 36 O P0 3 AD3 MOSN P1 5 06 MISO P1 6 OTF 34 O P0 5 AD5 SCK P1 7 O08 33 O P0 6 AD6 RSTOS 32 J P0 7 AD RXD P3 0 C 10 31 I EANPP TXD P3 1 O 11 30 O ALE PROG INTO P3 2 O 12 INT1 P3 3 O 13 TO P3 4 O 14 T1 P3 5 26 O P2 5 A13 WR P3 6 O RD P3 7 35 J P0 4 AD4 XTALZ P2 2 A710 XTAL1 L 2 P2 1 AS GND L _ P2 0 AB Fig 1 Pin Configuration of AT89S52 Volume levels are being switched by the help of analogue switching IC CD4066 CD6044 is a quad bilateral switch 2 i e it consists of four independent bilateral switches A single control signal is required per switch Both the p and n device in a given switch are biased ON or OFF simultaneously by the control signal As shown in Figure 2 the well of the n channel device on each switch is either tied to the input when the switch is ON or to VSS when the switch is OFF SIGNAL f IN OUT A OUT IN SIGNAL f OUTIN ve SIGNAL CTRL Bs D CTRL C 6 SIGNAL C Fig 2 Schematic diagram of CD4066 The device is being switched though the telephone line by the help of an optocoupler also called opto isolator phototransistor It is an electronic device designed to transfer electrical signals by utilizing light waves to provide coupling with electrical i
16. re channeled to the Analogy Switching IC CD4066 as input The switches in CD4066 are driven by the microcontroller AT89S52 1 Volume can be increased or decreased up pressing VOLUME UP and VOLUME DOWN button respectively The present volume level is displayed in the 7 Segment Display On pressing the LOW button the volume is decreased to a certain pre defined level and on pressing it for the second time or UP or DOWN buttons swaps back to the earlier set volume level The volume level for this case can be defined by pressing the LOW SET button which is pre defined to 1 The volume level shown in the 7 segment display is now set to be used as the low To set this level the user has to take the volume level to the level he needs to set as LOW by pressing the VOLUME UP and VOLUME DOWN keys and press the LOW SET key m If the present volume level is lower than the low set value the LOW button is not going to work To denote the LOW state the 7 Segment Display alternately glows Dp and the set level When the telephone receiver is picked up for receiving a call or to make a call the volume level jumps to a pre defined level 1 or a user defined value The volume level moves back to normal when the telephone receiver is put back into place After completing the call To set the volume level during the telephone call the TELVOL button is pressed after taking the volume level to the desired volume l
17. so outgoing call attempts d Volume levels can be set by the user according to the need 3 3 Working principle The main system runs on a AT89S52 1 microcontroller with a 7 segment display to display the volume level with 4 analogue switches CD41066 two for each channel left channel and the right giving us 8 defined sound levels The telephone line signaling if fed to the microcontroller through a optocoupler The serial communication procedure is implemented for the communication with the computer by the means of a USB tto serial converter 10 Switches for increasing and decreasing volume digitally muting audio telephone interfacing alarm interfacing volume defining are being supplied The following Figure 7 is a_ block diagrammatical representation of the project plan A SEVEN M TELEPHONE U SEGMENT I LINE INPUT p DISPLAY j l R a OPTOCOUPLER Pl o ag O i c N n USB INPUT p VOLTAGE N FROM PC U DIVIDER T R i o I L o L O ANALOG E T CD4066 Fig 7 Volume control system functional block diagram The sound level switching is implements by the means of voltage dividing with resistors attached in series and having input audio signal at one end and GND at the other La La 1 La 2 Li Lo IN ees LINE Rl R2 Ba Fig 8 Sound level switching implementation block diagram International Journal of Computer Applications 0975 8887 Volume 38 No 1 January 2012 The block diagrammatical repr
18. solation between its input and output The main purpose of an opto isolator is to prevent high voltages or 19 rapidly changing voltages on one side of the circuit from damaging components or distorting transmissions on the other side 3 The working is shown in Figure 3 where side 1 2 acts as input 1 e anode and cathode respectively and 3 4 as output i e collector and emitter respectively Fig 3 Schematic of an optocoupler The standard voltage for the telephone system is 48 volts DC Ringing voltage is much higher around 90 volts AC at a low frequency So the opto isolator prevents the main circuit from this high voltage and also helps in switching when the phone rings A Zener diode or breakdown diode is a special kind of diode which allows current to flow in the forward direction in the same manner as an ideal diode but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage Zener knee voltage or Zener voltage 4 Break down diodes Are p n diodes operated in the breakdown region of the reverse voltage characteristics 5 In this circuit a 13 volte zener diode has been used in the telephone line before the optocoupler to ensure that it only acts for voltage levels more than 13 volts i e the condition when the telephone receiver is down CATHODE Fig 4 Zener diode In the above figure Figure 4 a typical Zener diode has been represent
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