Cellphone Based Device Control With Voice Acknowledgement Avigyan Datta Gupta 1, Sayan Samanta 2, Avishek Acharjee 3 1,2 Future Institute of Engineering and Management, Kolkata-700150 3 Techno India, Kolkata-700150 Abstract In this paper we have presented a circuit that lets one to operate home appliances like light and water pump from office or any other remote place. So if one forgets to switch off light or other appliances while going out, it helps to turn off them with your cell phone.the cell phone works as the remote control for home appliances.one can control the desired appliance by pressing the corresponding key. The system also gives you voice acknowledgement of the appliance status. Keywords Microcontroller,Embedded System, Circuit Description, Detailed Pin Description. I. INTRODUCTION In recent years, there has been a rapid increase in wireless network deployment and mobile device market penetration. With various research that promises higher data rates, future wireless networks will likely become an integral part of the global communication infrastructure. Ultimately, wireless users will demand the same reliable service as today's wire-line network provides. Through our device controller we can represent a safe & secure wireless communication with proper authentication and less loss of data. The circuit of our proposed project has two parts: (i)the hardware part (ii)the software part The hardware part comprises of microcontroller AT89C51, DTMF decoder MT8870, voice recording/playback device APR9600 and a few discrete components. Microcontroller AT89C51 is the heart of the circuit. It is a low-power, high performance, 8bit microcontroller with 4 KB of flash programmable and erasable read only memory used as on-chip program memory, 128 bytes of RAM, 32 individually programmable input/output lines, a five vector two-level interrupt architecture, on-chip oscillator and clock circuitry. The software part consists of a program for the microcontroller is written using BASCOM microcontroller programming software. A. Components Required Hardware Components: Hardware components comprises of the following:- 169 Microcontroller [AT89C51] Voice recording and playback device[apr9600] DTMF receiver [MT8870] Relay [ULN2003] Power supply LED Resistors Capacitors Diodes Switch Crystal Oscillator Electric mic Speaker Cellphone with headset Software Components: Software components comprises of the following:- BASCOM microcontroller programming software Assembly language B. Introduction To Embedded Systems I) Definition: Embedded System Any sort of device which includes a programmable computer, but itself is not intended to be a general-purpose computer [1]. II) What is an Embedded System An embedded system is a microcontroller / digital signal microprocessor based system that is designed to be flexible and built to control or monitor the functions of equipment, machinery, plant and many devices in common use today. III) Desktop vs. Embedded System In contrast to Desktops that performs a Variety of tasks an Embedded System performs a Single, Well-Defined Task. The System has a Processor, Associated Peripherals, and Software for a Specific Purpose. For example, in a Mobile Phone the Embedded Processor needs to Process Voice (to Send and Receive Speech Signals) as well as implement Communication Protocols. The Hardware is Custom Built for the Specific Purpose. Unlike a PC, embedded system is not designed to be programmed by an end user. Embedded system always runs a fixed application.
II. METHODOLOGY A. Problem Description In recent years our modern life style becomes so busy and full of task schedule that we often forget to do some simple duties. Such as forget to switch of our household appliances. We don't bother about our these types of carelessness every time, but this can give us real trouble sometime. Unnecessarily energy is consumed. For too much consumption of energy, the generated heat can damage the device. This damage cause a serious interruption in our task schedule, besides some loss of money and time also. But it is not always possible for us to switch off the devices from the remote place. So our aim is to control the household devices from the remote places. We use wireless network to implement our project. Through our device controller project we try to represent a safe & secure wireless communication to control the devices.[2],[3],[4],[5] Status Indicator Switch To Decode Board AT89C51 Microcontroller Voice Controlling & Playback Device Microphone Speaker DTMF Decoder Cellphone Relay Driver Fig-1 Functional Block Diagram 170
Fig- 2 Circuit Diagram B. Circuit Description It comprises of microcontroller AT89C51, DTMF decoder MT8870, voice recording/playback device APR9600 and a few discrete components. Microcontroller AT89C51 is at the heart of the circuit. It is a low power, high-performance, 8-bit microcontroller with 4kB of PEROM used as on-chip program memory, 128 bytes of RAM used as internal data memory, 32 individually programmable I/O lines divided into four 8-bit ports, two 16-bit programmable timers/counters, a five-vector twolevel interrupt architecture, on-chip oscillator and clock circuitry.a 11.0859 MHZ crystal (Xtal1) is used to provide basic clock frequency of microcontroller. Capacitor C3 and resistor R3 from the power-on reset circuit, while push-toon switch S20 is used for manual reset.port pins P1.0 through P1.7 of the microcontroller are configured to get the input from switches S1 through S8.pins from port P1 are pulled high via resistor network RNW1. 171 Port pins P2.0 through P2.4 are configured to receive the decoded DTMF signal from DTMF receiver MT8870.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 3.579MHz crystal (Xtal2).In DTMF receiver MT8870 (IC3), capacitor C12 is used to filter the noise and resistors R6 and R7 helps 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 the 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 the 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 the voltage at St. Port P3 pins P3.6 and P3.7 of IC1 are configured to select the control source for the devices. These are connected to DIPswitches S17 & S18 and pulled high via resistors R2 and R1, respectively. Here, we are using two control sources, switches and mobile's key. DIP switches S17 & S18 select the control sources. Pin 2.5 of Port P2 is configured to show the rest status. That is, if none of the control sources is selected by DIP switches S17 & S18, LED1 glows. Resistor R14 limits the current through LED1. Voice acknowledgement is provided by APR9600 (IC2). It is a single-chip voice recording and play back device that can record and play multiple message at random or in sequential mode for 60 seconds. The user can select sample rates with corresponding-quality recording lengths. Microphone amplifier, automatic gain control circuits, internal output amplifier and message management are some of the features of the APR9600.Here the APR9600 is configured in random-access mode, which supports two, four & eight messages of fixed durations. The length of each message is the total recordings length available divided by the total number of memory segments/tracks enabled. Audio processor can store up to eight voice messages. Port P0 pins & P2.7 are configured to communicate with IC2. Port P0pins trigger selection of the message. Port pin P2.7 is the input signal to identify whether the voice message is playing or not. Pins P3.0 through P3.5 of port P3 control the devices with the help of relays RL1 through RL6 via relay IC4.A speaker is connected to IC2 for audio output. The speaker output drives the microphone input of the mobile for audio acknowledgement. An electrets microphone MIC1 is connected to IC2 to record the voice in IC2. Led2 flashes to show the busy status of IC2 during recording & playback. The audio message to be recorded in APR9600, by using trigger switches S9 through S16. SPST switch S19 is closed for recording and switch S19 is opened for playback. C. Component Values and Ratings Name of Values SL No. the components 1 AT89C51 4K PEROM, CMOS, 8 bit 2 APR9600 Operating Current: 25 ma typical. Standby Current: 1 ua typical. 3 MT8870 3.579545MHz, MAX: 7V, 10mA, 500mW Ratings 0-20 MHz, 5V±15% 5V±20% 5V± 5% 4 7806 6v 1A, 6V,±4%, Ta 5 1N4007 diode 8pF junction capacitance 6 Resistors 10K,100K, 470K, 220K,39K,4.7K, 1K, 220K, 470 ohm = -40 C to +125 C Peak reverse voltage:1000v, peak rev current: 5uA ¼ W, ±5% CARBON 7 Capacitors 33pF, 0.1uF ceramic 8 Capacitors 10uF, 4.7uF, 22uF, 1000uF 16v, 50v electrolytic 9 Capacitors 0.22uF, 0.47uF polyester 10 Crystal oscillator 11.0592 MHz, 3.579 MHz 11 Speaker 16ohm 1W Table 1: Table for component values and ratings 172
D. AT89C51 Specification I) Diagram of Microcontroller Used ie AT89C51: (II) VCC Supply voltage. GND Ground Port 0 Table 1: Pin out diagram of AT89C51 Detailed Pin Description of Microcontroller Used i.e. AT89C51: Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs. Port 0 can also be configured to be the multiplexed low-order, address/data bus during accesses to external program and data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pull-ups are required during program verification. Port 1 Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table. Port 2 Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification. Port 3 Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups. Port 3 also serves the functions of various special features of the AT89C51, as shown in the following table. RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. ALE/PROG Address Latch Enable is an output pulse for latching the low byte of the address during accesses to external memory. 173
This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the micro controller is in external execution mode. PSEN Program Store Enable is the read strobe to external program memory. When the AT89C52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. EA/VPP External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin also receives the 12-volt programming enablevoltage (VPP) during Flash programming when 12- volt programming is selected. XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier. III. CONCLUSION So, in this project we have shown that using a simple extra cellphone, you can control your power hungry home appliances. This will eventually reduce your carbon footprint, as well as your electricity bill. Many similar zigbee based controller are already in market, but that will limit your within a range upto 100 meters. This cost effective solution has a great potential in our everyday busy schedule. REFERENCES [1 ] Computers as components: principles of embedded computing system by Wayne Hendrix Wolf. Chapter 1.2. [2 ] http://www.atmel.com/dyn/resources/prod_documents/doc0265.pdf [3 ] http://akizukidenshi.com/download/apr9600.pdf [4 ] http://www.diodes.com/datasheets/ds28002.pdf [5 ] http://www.datasheetarchive.com 174