Microcontroller based mobile control of electronics appliances
Synopsis
Microcontroller based mobile control Of electronics appliances Submitted in partial fulfillment award of requirement for the degree in bachelors of engineering(electronics & electrical) from kiit college of engg. Under the guidance of mr. Anurag sharma. Submitted by: Pankaj yadav(1431) Suman yadav(1450) Vipul avasthi(1460) Mohammad jalaludin(1421) Reena yadav(1441) Microcontroller based mobile control Of electronics appliances (or) Smart home automation system Home automation refers to the automatic control of things around the home. From this project we can control any electrical appliance through mobile or landline from any part of the country. In this one base unit is connected to the basic landline or with the mobile phone in parallel with the landline phone,in the case of landline but in the case of mobile phone we use hand free option logic. When we want to control any appliance through outer phone then first we dial the home number,bell is ok ringing and after few bell phone is automatic on and switch on the base unit to operate. Now we press the 8-digit excess code,one by one if the excess is ok then unit give an ack in the form of tone pulse and switch on the base unit. Now again we press the switch on/off code to on/off any electrical appliances. With the help of this code unit is on and base unit give a acknowledge pulse for on and off separately. Ac register signaling is used in dtmf telephones, here tones rather than make/break pulse are used for dialing, and each dialed digit is uniquely represented by a pair of sine waves tones. These tones (one from low group for row and another from high group for column) are sent to the exchange when a digit is dialed by pushing the key, these tone lies within the speech band of 300 to 3400 hz, and are chosen so as to minimize the possibility of any valid frequency pair existing in normal speech simultaneously. Actually, this minimisator is made possible by forming pairs with one tone from the higher group and the other from the lower of frequencies. A valid dtmf signal is the sum of two tones, one from a lower group (697-940 hz) and the other from a higher group (1209-1663 hz). Each group contains four individual tones. This scheme allows 10 unique combinations. Ten of these codes represent digits 1 through 9 and 0. Tones in dtmf dialing are so chose that none of the tones is harmonic of are other tone. Therefore is no change of distortion caused by harmonics. Each tone is sent as along as the key remains pressed. The dtmf signal contains only one component from each of the high and low group. This significaly simplifies decoding because the composite dtmf signal may be separated with band pass filters into single frequency components, each of which may be handled individually. Circuit diagram Cont. List of components • dtmf decoder (ic mt 8870) • bcd to decimal decoder (ic 74154) • decade counter (ic 4017) • microcontroller (ic 89c51) • flash memory (ic 2402 ) • regulator (ic 7805) • transistors (bc 548) • diode (in4148) • crystal oscillator • optocoupler (moc3021) • triac (bt136) • led • capacitor • step down transformer • hands free Working In this project our first part is dtmf decoder. Dtmf ic receives the dtmf pulse and then converted into binary coded decimal. Pin no 18 of the ic is connected to positive supply. In this circuit we use 5 volt regulated power supply for the smooth working. Dtmf signal is applied to the pin no 2 and 3 of the ic through resistor and capacitor network. Capacitor 0. 1 microfarad work as a dc blocking capacitor. Pin no 5, 6, 9 is connected to the ground pin. Pin no. 7 and 8 is connected to the 3. 57945 mhz crystal. Pin no 16 and 17 is connected to rc network work as a auto reset, when we switch on the power supply. Bcd output is available on the pin no 11,12,13,1,4, and this output is connected to the microcontroler 89c51 Our next part of the circuit is ic 89c51. 89c51 is 40 pin ic. Pin no 40 of the ic is connected to the positive supply. Pin no 9 is rest pin. One capacitor and resistor network is connected to pin no 9. This microcontroller has a total of four input output ports each 8 bit wide. We use port 2 as a bcd input. Output from the 8870 is connected to the p2 – 4 pins. 8870 port2 ic pin Pin 11 p2. 0 21 Pin 12 p2. 1 22 Pin 13 p2. 2 23 Pin 14 p2. 3 24 Output is available on the port1 and port 3; here we use only 10 output from the microcontroller. All the output is available on the port p1 P0. 0 pin no 39 P0. 1 pin no 38 P0. 2 pin no 37 P0. 3 pin no 36 P0. 4 pin no 35 P0. 5 pin no 34 P0. 6 pin no 33 P0. 7 pin no 32 P3. 0 pin no 10 P3. 1 pin no 11 All the output led is connected to this output. Note that 0 logic is available on these pin , so cathode of the led is connected to this pin. Another pins of the port 3 is also connected for another useful uses. P3. 3 acknowledge of code lock P3. 4 time indication of the code lock P3. 5 led indication of sound output for on/off signal P3. 2 output frequency for opto-coupler input. Led output of the microcontroller is further connected to the triac circuit through opto-coupler circuit. Output from the microcontroller is firstly connected to the optocoupler pin no 1. This optocoupler is a special optocoupler. The moc3121 is optically isolated triac driver devices. These devices contain a infra red emitting diode and a light activated silicon bilateral switch. They are specially designed for interfacing between electronics controls and power triaces to control resistive and inductive loads for 240 volt ac operation. Pin no 1 is anode pin of infra red transmitter Pin no2 is cathode pin of infra red transmitter Pin no 4 and 6 is the output pin Pin no 6 is output pin and connected to the gate of the triac through 100 ohm resistor. At the output of the triac we control any 220 load. In this project its our choice, how many optocoupler we interface this circuit. If we use 10 opto coupler then we interface 10 load output with this circuit. Now when ic receive any pulse then output led is on and then load is on. Again we press the same code then led is off and load is also off. Working of this microcontroller is depending on the combination lock. When combination lock gives an output on port3. 3 then only ic sense the signal. Complete circuit is divided into following parts:  dtmf decoder  microcontroller  automatic control of circuit through outer phone Dtmf decoder Dtmf decoder is a very easy to use program to decode dtmf dial tones found on telephone lines with touch tone phones. Dtmf decoder is also used for receiving data transmissions over the air in amateur radio frequency bands. The following are the frequencies used for the dtmf (dual-tone, multi-frequency) system, which is also referred to as tone dialing. The signal is encoded as a pair of sinusoidal (sine wave) tones from the table below which are mixed with each other. Dtmf is used by most pstn (public switched telephone networks) systems for number dialing, and is also used for voice-response systems such as telephone banking and sometimes over private radio networks to provide signaling and transferring of small amounts of data. In dtmf decoder circuit we use ic 8870 ic. Ic 8870 is a dtmf decoder ic. Ic 8870 converts the dual tones to corresponding binary outputs. Ac register signaling is used in dtmf telephones, here tones rather than make/break pulse are used for dialing, and each dialed digit is uniquely represented by a pair of sine waves tones. These tones (one from low group for row and another from high group fro column) are sent to the exchange when a digit is dialed by pushing the key, these tone lies within the speech band of 300 to 3400 hz, and are chosen so as to minimize the possibility of any valid frequency pair existing in normal speech simultaneously. Actually, this minimisator is made possible by forming pairs with one tone from the higher group and the other from the lower of frequencies. A valid dtmf signal is the sum of two tones, one from a lower group (697-940 hz) and the other from a higher group (1209-1663 hz). Each group contains four individual tones. This scheme allows 10 unique combinations. Ten of these codes represent digits 1 through 9 and 0. Tones in dtmf dialing are so chose that none of the tones is harmonic of are other tone. Therefore is no change of distortion caused by harmonics. Each tone is sent as along as the key remains pressed. The dtmf signal contains only one component from each of the high and low group. This significaly simplifies decoding because the composite dtmf signal may be separated with band pass filters into single frequency components, each of which may be handled individually. Microcontrollers A microcontroller is a computer-on-a-chip. It integrates the features like read-write memory for data storage,read only memory such as flash for code storage,eprom for permanent data storge,peripheral devices and input/output devices. By reducing the size,cost and power consumption compared to separate designed microprocessor,memory,input/ou tput deveices , microcontrollers made it economical to electronically control of many more process. Here 8051 microcontrollers are used and some basic features of the 8051 are following : 1) 8-bit cpu. (consisting of the ‘a’ and ‘b’ registers) Most of the transactions within the microcontroller are carried out through the ‘a’ register, also known as the accumulator. In addition all arithmetic functions are carried out generally in the ‘a’ register. There is another register known as the ‘b’ register, which is used exclusively for multiplication and division. 2) 4k on-chip rom The instructions written for the microcontroller,are put on this memory. To make these instructions safe, and not get deleted or changed during execution. We load these instructions into rom. The size program to be written is bound to vary depending on the application, and the number of lines. So the space can be extended by connecting to 64k of external rom if required. 3) 128 bytes on-chip ram This is the space provided for executing the program in terms of moving data, storing data etc. 4) 32 i/o lines. (four- 8 bit ports, labeled p0, p1, p2, p3) Each port has 8 bits. There are a total of four ports named p0, p1, p2, p3, giving a total of 32 lines. These lines can be used both as input or output. 5) two 16 bit timers / counters A microcontroller normally executes one instruction at a time. However certain applications would require that some event has to be tracked independent of the main program. The manufacturers have provided a solution, by providing two timers. These timers execute in the background independent of the main program. Once the required time has been reached, they can trigger a branch in the main program. These timers can also be used as counters, so that they can count the number of events, and on reaching the required count, can cause a branch in the main program. 6) full duplex serial data receiver / transmitter The 8051 microcontroller is capable of communicating with external devices like the pc etc. Here data is sent in the form of bytes, at predefined speeds, also known as baud rates. The transmission is serial, in the sense, one bit at a time 7) 5- interrupt sources with two priority levels (two external and three internal) Interrupts can be set to either the timers, or to some external events. Whenever the background program has reached the required criteria in terms of time or count or an external event, the branch is taken, and on completion of the branch, the control returns to the main program. Priority levels indicate which interrupt is more important, and needs to be executed first in case two interrupts occur at the same time. 8) on-chip clock oscillator. This represents the oscillator circuits within the microcontroller. Thus the hardware is reduced to just simply connecting an external crystal, to achieve the required pulsing rate. Automatic control of circuit through outer phone Electronics combination lock:- In this section we use two ic one is ic 74154 and second is ic 4017. Both ic generate a combination sequence by which we enable the microcontroller. When we want to switch on the base unit by outer phone then phone is automatic on after few bells, this is achieve by another circuit. But after few bells when phone is on and unit require a code of 9 numbers. When we press proper codes then only micrcontroller allow us to switch on the circuit. First ic of this section is ic 74154. Ic 74154 is bcd to decimal decoder. 74154 is active low ic. Pin no 20,21,22,23 is connected to dtmf decoder ic. Pin no 18 and 19 of this ic is connected to the collector of one npn transistor base of the npn transistor is connected to the pin no 15 of the ic 8870. When dtmf decoders decode the signal at that time pin no 15 is on for a time and acknowledge the signal. This signal is fed to the base of npn transistor through 1 kohm resistor. When this signal is coming then 74154 is on and gives an output. If we press the proper code in steps then at every digit of code 74154 is on and gives the corresponding output as per the digit. Output of the ic 74154 is connected to the pnp transistor base point through 10 k ohm resistor. Emitter of the all pnp transistor is connected output of the decade counter circuit. Here we use ic 4017 as a decade counter circuit. Pin no 16 is the positive supply pin and pin no 8 is the negative pin. Pin no 14 of the ic is clock input of the ic. On starting mode when is in on reset mode then its start from the zero point. O means first output is available on the pin no 3. Its means pin no 3 is positive in first output. Now ic 4017 receive a clock pulse on pin no 14 then counter shifts its output from pin no 3 to nest output not 1 , pin no 2. As we press the proper code then ic 74154 gives an output and this output is available on the output pin, with the help of this output pnp transistor is on and positive output is available on the collector point of the pnp transistor. All the pnp transistor collector point is connected together is and reconnected to the clock input of the ic 4017 through rc network to another npn transistor. By this npn transistor we give a clock pulse to the pin no 14 of the ic 4017. As the counter move after incoming clock pulse then last output is available on the pin no 9. As the last output is available on the pin no 9. After getting a voltage on the pin no 9 we switch on the next pair of npn transistor. Output of first npn transistor is on collector is connected to the port p3. 4 to give a acknowledge signal that code lock is loaded successfully. Output of this npn transistor is again connected to the connected to the base of next npn transistor. Collector of this npn transistor disables the pin no 18 of the ic to receive any further code input of the signal Auto swith on phone form incoming call:- In this project if we use mobile phone as a receiver then we use handfree kit. After using a hand free kit we assign our phone to an auto action mode. In auto action mode we assign our phone to on itself after some time. In every phone there is an option of auto answer mode after few bells. Our next circuit is automatic switch on this circuit on the incoming call. In the case of landline phone we use auto hook up circuit to switch on the base unit automatically. For this circuit we use one opto coupler circuit + one timer circuit + one counter circuit. Signal from telephone lines is connected to the opto coupler pin no1. Pin no 2 is ground pin. Pin no 3 is also ground pin. Pin no 4 is the output pin no of this opt coupler. When incoming call connected to opto coupler the opto coupler is on and output pulse is connected to the pin no 2 of the monostable timer circuit. Pin no 4 and 8 is connected to the positive supply and pin no 1 is connected to the negative supply. Pin no 3 is output pin and this pin is connected to the next ic. Next ic is counter circuit. In counter circuit we use ic 4017. Pin no 16 is connected to the positive supply. Pin no 8 is connected to the negative supply. Pin no 13 and 7 is an output pin and connected to the relay through nun transistor. When call in coming then due to short pulse from the bell opt coupler is on/off for the frequency of the bell. But when output is connected to ic 555 then ic 555 is switch on for a time period. And for every pulse timer is on for a second and output from timer is connected to counter circuit. We use forth output of the counter so that after receiving forth pulse counter is on and switch on the relay circuit and connect the main circuit to the telephone instrument. Main part of this project is program code. Programming detail of the mobile control mobile control Program is to be wriiten in the assemblly language in the 8051 assembler. Assembler assemble the software and then this software is further converted into the hex code with the help ofassembler itself. In this program we receive the data from the dtmf decoder ic and then this bcd input is processed by the microcontroller. Applications: Security system & access control,home theater & entertainment,lighting,phone systems,thermostats,networking ,irrigation etc. Future scope  the main advantage of this circuit is its unlimited range, as connection is established using mobile phones which have dtmf tones are attached.  also operation is not based on infrared transmission due to which positioning and adjustments are not required at all.  thus working is easy & only appliance’s connection to kit and kit’s to mobile is to be done just plug ‘n play. ’  flexibility is provided in a way that one can connect less number of appliances in starting for testing & later on expand the circuitry as per requirement.  using the teleremote switch or mobile phone one can control switching up to 10 appliances. More than 10 appliances can be controlled by inserting a multiplexer.  just by using dial keypad of mobile phone from where we are calling, we can perform on/off operation of the appliances. These appliances have to be connected to phone line through the kit, at the called side.  the ranges of appliances that are controlled depend upon the person’s usage. Room heater, water heater, music system or any other electrical / electronic appliance switching can be controlled once they are connected to kit.  energy & electricity are saved using this kit.  by using this project kit, one can save money, time as well as enhance convenience, safety & fun. conclusion  we have all gotten used to controlling our tv from couch, just wait until we are able to dim lights as well. Imagine adjusting the temperature from our bed or controlling the volume of our whole house audio system from any room. Or can you imagine the wall heater in our bathroom coming on automatically 5 minutes before our alarm clock goes off so that it is warm when we enter.  we all are used to opening the garage door from the car, but you will be surprised how mush safer you will feel coming home to a lit home and even turning on more lights from our mobile phone upon our arrival. With a couple of basic products, we can have our whole house light up when there is motion detected at any corner of our house.  high technology products for the home are fun to use & share with others, whether viewing visitors at our front door on our tv or tuning our stereo by using voice recognition. And when it comes to impressing the friends, you’ll be happy to show off your new found applications.  with the broad selection of home automation products offered one can control just about anything one wishes at home.
Key technologies Used in this project: assembly language programming,microcontroller & GSM technique
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microcontroller based mobile control of electronics appliances
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