ã€Abstract】 Introduce the use of power line MODEM, power line carrier form, remote centralized control of home appliance network, which can realize the selection control of any home appliance and group control of home appliance network.
Keywords: Power Line Carrier Remote Control AT89C52
1 Introduction Home appliance network control is a remote control of multiple home appliances connected to the network, which achieves a high degree of automation in housework and home management, and is one of the development directions of home appliance automation systems.
How to form a network for data communication by household appliances is an important issue for home appliance network control. If the traditional method of laying special cables is used, the installation and maintenance costs of these cables are relatively high, and they cannot be conveniently branched or connected. In all communication methods, the power line carrier channel is the most direct and economical communication medium. However, there are various electromagnetic interferences on the power line, which must be eliminated by effective means. This article introduces the use of power line MODEM chip LM1893, using the form of power line carrier, to design a reliable home appliance network control system to remotely control multiple home appliances located in the same distribution transformer.
2 System composition and working principle The system composition and principle block diagram are shown in Figure 1. The system consists of a main control unit, 220V power line transmission channel and several controlled units connected in parallel on the power line.
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The main control unit is mainly composed of control circuit and modulator. The control interface is a 4 × 4 keyboard. The numeric keys on the keyboard are the addresses of the controlled appliances 0-9. The function keys (ON, OFF, ALLOFF, RST) on the keyboard are used to turn on / off and control the controlled appliances. On / off and reset status control functions. The control circuit encodes the keys, and the output encoded signal becomes a high-frequency signal through the modulator. The modulation carrier frequency is generally selected within the range of (40 ~ 600) kHz according to the frequency characteristics of the power line. In this system, the modulation frequency is selected to be 160 kHz. Frequency modulation. After being modulated and filtered, the modulated high-frequency signal is sent to the power line for transmission by the coupling capacitor.
The controlled unit is mainly composed of frequency selective amplification, demodulation, address discrimination and execution circuit and controlled household appliances. The frequency-modulated signal transmitted by the power line enters the frequency-selection amplifier stage through the coupling capacitor. After the amplified frequency-modulated signal is demodulated, decoding and address discrimination are performed. If the coded signal is not addressed to this address unit, the execution circuit does not execute any commands. When the address in the coded signal is the same as the address of the controlled unit, the execution circuit will perform the state control function in the coded signal, and the relay will perform the pull-in or release action to realize the on / off control of the target electrical load.
3 Power line MODEM chip LM1893 and application circuit introduction LM1893 is a MODEM chip produced by the National Semiconductor Corporation dedicated to transmitting data on the power line, which can perform half-duplex data communication. When sending data, the baseband data performs FSK modulation on the carrier, and the modulated carrier is added to the power line through the on-chip power driver. When receiving, due to the use of a phase-locked loop-based demodulator and an impulse noise filter designed for impulse noise interference, The dynamic range of the received signal is wide and the sensitivity is extremely high.
The typical application circuit of LM1893 is shown in Figure 2. The fifth foot TX / RX is the receiving and sending state control pin: connect the high level to the transmitting state, and connect the low level to the receiving state. When transmitting, the data to be sent is input from the 17th pin, and the flow control oscillator inside the LM1893 is controlled to generate an FSK signal with a center frequency of about 160 kHz, which is amplified and output from the 10th pin, and is coupled to the power line. When receiving, the FSK signal from the power line passes through the high-pass filter loop composed of high-voltage coupling capacitor and transformer, and then selects the frequency through the LC parallel resonant circuit. It is input by the 10th pin of LM1893, converted into "1" and "0" data are output by the 12th pin. Pin 12 is designed as an open collector and can be directly interfaced with TTL and CMOS circuits. By adjusting the 5K adjustable resistor, the center frequency of the LM1893 can be selected within the range of 50 ~ 300kHz.
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4 Main control unit circuit design
4.1 Control circuit design
4.1.1 Hardware design The user controls the switch operation of electrical appliances through the buttons. For example, press the two keys "ON" and "7" in sequence to realize the action of turning on the seventh electrical appliance. Press the "ALLON" function key to realize the full opening of electrical appliances 0-9. Four LEDs display corresponding functions and digital information.
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4.1.2 Software design The software design structure is shown in Figure 4. When a keyboard is pressed, an interrupt INT0 is generated, the key value is read in the interrupt service program, the key value is converted into the keyboard number, stored in the internal RAM of 89C52, and a specific number is set in a specific unit of the RAM as The data source is stored in the flag of 8279. Once the main program inquires that there is a key flag, it processes the keyboard information. According to the different function keys, it transfers to the corresponding program branch and sends the corresponding control code.
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4.2 Power line carrier modulation circuit The power line carrier modulation circuit is shown in Figure 5. Connect pin 5 of LM1893 in the typical application circuit of LM1893 to high level, and set it as the transmitting signal state. The external coding chip PT2262 is enough.
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The D0 ～ D3 end of the PT2262 encoder inputs the 4-bit control code generated by the 89C52 of the main control unit. The TE end is the sending control end, and the low level is effective. PT2262 encodes the control code, serially outputs the data stream representing the input state of D0 ～ D3 from DO terminal, and is connected to the 17 pin of LM18 93. The control signal sent from 89C52 is modulated by LM1893 to send out a carrier signal and then the intermediate frequency Transformers and coupling capacitors are sent to the power line. In addition, A0 to A5 of PT2262 are address code input, which can be edited into three states of "1", "0", and "open circuit" for identification of multiple electrical appliances at the receiving end. Only when the addressing of the decoder at the receiving end is completely the same as the addressing of the encoder PT2262 at the sending end is A0 to A5, the information is received.
5 Controlled unit circuit design The function of the controlled unit is to decouple the high-frequency signal on the power line after coupling, frequency selection and amplification, and then to decode the state of the controlled electrical appliance after address decoding.
5.1 Power Line Carrier Demodulation Circuit Ground the 5 pins of LM1893 in the typical application circuit of LM1893 and set it to the receiving signal state, just connect the external decoder chip PT2272. The power line carrier demodulation circuit is shown in Figure 6.
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The frequency-modulated signal transmitted by the power line is amplified by frequency selection and demodulated by the LM1893. The demodulated signal is output to the decoder PT2272 by the 12 pins of the LM1893. If the A0 ～ A5 address input status of the prepared PT2272 is completely the same as the address status set by the transmitter PT2262, the receiving and sending addresses match, so that the signal can be correctly decoded by the PT2272 after demodulation, and the VT becomes high, indicating that the transmission is valid. PT2272 outputs the same four-bit control codes D0 ～ D3 as the transmitter to the address discrimination and execution circuit to control the switch status of the electrical appliances.
5.2 Address discrimination and execution circuit The address discrimination and execution circuit is shown in Figure 7. The address decoding adopts the high-speed TTL4 ~ 16 line decoder 74HC154, and its input A ~ D end is connected with the control code D0 ~ D3 output from the decoder PT2272. The CP end of the D flip-flop 74HC74A is connected to 10 output ends ("0" to "9") of the decoder representing the address code of the appliance. When the keyboard keys of 0-9 are pressed, the output level of the decoder is effective. If the address code of the controlled electrical appliance entered on the keyboard is the same as the preset address of the dial switch SW-10 of the controlled unit (dial switch Set the address number of the controlled appliance), the high level connected to the D terminal of the D flip-flop will appear on the Q terminal, then Q is low, making the decoder output terminals Y10 and Y11 ON and ON The OFF command can activate the relay through two OR gate circuits to control the switch of the electrical appliance. If the address code entered on the keyboard does not match the address set by the DIP switch, the CP of the D flip-flop is invalid. At this time, Q remains high, the OR gate is disabled, and the ON / OFF command is invalid. When the ALLON (Y12 terminal output) command or the ALLOFF (Y13 terminal output) command is valid, the Q terminal of the R-S flip-flop can be set to 1 or 0 through the AND gate, regardless of whether the OR gate is open. To realize the group control function of fully open or fully closed.
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6 Conclusion This article introduces a home appliance network control system that uses power lines as the communication medium. The main control unit is a centralized controller of household appliances with small size, low power consumption and convenient portability, which realizes remote switch control of multiple household appliances (rice cookers, electric lamps, etc.). The controlled unit is a plurality of receiving sockets matched with the home appliance centralized controller, and the address number of the connected electric appliance is set on the dial switch on the socket, thereby forming a home appliance networking remote control system. The system is easy to install and use, with stable and reliable performance, but the scope of use is limited to the same distribution transformer, and the effect of in-phase transmission is the best. Out-of-phase transmission requires a 600V, 1μF withstand voltage capacitor to be connected to the phase line to provide a signal path. The main disadvantage of this system is that the communication transmission distance is limited, currently only 500m is best. If you want to achieve practicality, there is a special advancement to increase the communication transmission distance.
references
1 Zhang Youde, etc. The principle, application and practice of single chip microcomputer. Shanghai: Fudan University Press. 1992
2 Wang Furui et al. Design of single-chip microcomputer measurement and control system. Beijing: Beijing University of Aeronautics and Astronautics Press. 1998
3 Zhang Yuanzheng. High frequency power line communication. Beijing: Water Power Press, 1983
4 NaTIonal Semiconductor CorporaTIon. Linear Data Book. 1992
Keywords: Power Line Carrier Remote Control AT89C52
1 Introduction Home appliance network control is a remote control of multiple home appliances connected to the network, which achieves a high degree of automation in housework and home management, and is one of the development directions of home appliance automation systems.
How to form a network for data communication by household appliances is an important issue for home appliance network control. If the traditional method of laying special cables is used, the installation and maintenance costs of these cables are relatively high, and they cannot be conveniently branched or connected. In all communication methods, the power line carrier channel is the most direct and economical communication medium. However, there are various electromagnetic interferences on the power line, which must be eliminated by effective means. This article introduces the use of power line MODEM chip LM1893, using the form of power line carrier, to design a reliable home appliance network control system to remotely control multiple home appliances located in the same distribution transformer.
2 System composition and working principle The system composition and principle block diagram are shown in Figure 1. The system consists of a main control unit, 220V power line transmission channel and several controlled units connected in parallel on the power line.
The main control unit is mainly composed of control circuit and modulator. The control interface is a 4 × 4 keyboard. The numeric keys on the keyboard are the addresses of the controlled appliances 0-9. The function keys (ON, OFF, ALLOFF, RST) on the keyboard are used to turn on / off and control the controlled appliances. On / off and reset status control functions. The control circuit encodes the keys, and the output encoded signal becomes a high-frequency signal through the modulator. The modulation carrier frequency is generally selected within the range of (40 ~ 600) kHz according to the frequency characteristics of the power line. In this system, the modulation frequency is selected to be 160 kHz. Frequency modulation. After being modulated and filtered, the modulated high-frequency signal is sent to the power line for transmission by the coupling capacitor.
The controlled unit is mainly composed of frequency selective amplification, demodulation, address discrimination and execution circuit and controlled household appliances. The frequency-modulated signal transmitted by the power line enters the frequency-selection amplifier stage through the coupling capacitor. After the amplified frequency-modulated signal is demodulated, decoding and address discrimination are performed. If the coded signal is not addressed to this address unit, the execution circuit does not execute any commands. When the address in the coded signal is the same as the address of the controlled unit, the execution circuit will perform the state control function in the coded signal, and the relay will perform the pull-in or release action to realize the on / off control of the target electrical load.
3 Power line MODEM chip LM1893 and application circuit introduction LM1893 is a MODEM chip produced by the National Semiconductor Corporation dedicated to transmitting data on the power line, which can perform half-duplex data communication. When sending data, the baseband data performs FSK modulation on the carrier, and the modulated carrier is added to the power line through the on-chip power driver. When receiving, due to the use of a phase-locked loop-based demodulator and an impulse noise filter designed for impulse noise interference, The dynamic range of the received signal is wide and the sensitivity is extremely high.
The typical application circuit of LM1893 is shown in Figure 2. The fifth foot TX / RX is the receiving and sending state control pin: connect the high level to the transmitting state, and connect the low level to the receiving state. When transmitting, the data to be sent is input from the 17th pin, and the flow control oscillator inside the LM1893 is controlled to generate an FSK signal with a center frequency of about 160 kHz, which is amplified and output from the 10th pin, and is coupled to the power line. When receiving, the FSK signal from the power line passes through the high-pass filter loop composed of high-voltage coupling capacitor and transformer, and then selects the frequency through the LC parallel resonant circuit. It is input by the 10th pin of LM1893, converted into "1" and "0" data are output by the 12th pin. Pin 12 is designed as an open collector and can be directly interfaced with TTL and CMOS circuits. By adjusting the 5K adjustable resistor, the center frequency of the LM1893 can be selected within the range of 50 ~ 300kHz.
4 Main control unit circuit design
4.1 Control circuit design
4.1.1 Hardware design The user controls the switch operation of electrical appliances through the buttons. For example, press the two keys "ON" and "7" in sequence to realize the action of turning on the seventh electrical appliance. Press the "ALLON" function key to realize the full opening of electrical appliances 0-9. Four LEDs display corresponding functions and digital information.
4.1.2 Software design The software design structure is shown in Figure 4. When a keyboard is pressed, an interrupt INT0 is generated, the key value is read in the interrupt service program, the key value is converted into the keyboard number, stored in the internal RAM of 89C52, and a specific number is set in a specific unit of the RAM as The data source is stored in the flag of 8279. Once the main program inquires that there is a key flag, it processes the keyboard information. According to the different function keys, it transfers to the corresponding program branch and sends the corresponding control code.
4.2 Power line carrier modulation circuit The power line carrier modulation circuit is shown in Figure 5. Connect pin 5 of LM1893 in the typical application circuit of LM1893 to high level, and set it as the transmitting signal state. The external coding chip PT2262 is enough.
The D0 ～ D3 end of the PT2262 encoder inputs the 4-bit control code generated by the 89C52 of the main control unit. The TE end is the sending control end, and the low level is effective. PT2262 encodes the control code, serially outputs the data stream representing the input state of D0 ～ D3 from DO terminal, and is connected to the 17 pin of LM18 93. The control signal sent from 89C52 is modulated by LM1893 to send out a carrier signal and then the intermediate frequency Transformers and coupling capacitors are sent to the power line. In addition, A0 to A5 of PT2262 are address code input, which can be edited into three states of "1", "0", and "open circuit" for identification of multiple electrical appliances at the receiving end. Only when the addressing of the decoder at the receiving end is completely the same as the addressing of the encoder PT2262 at the sending end is A0 to A5, the information is received.
5 Controlled unit circuit design The function of the controlled unit is to decouple the high-frequency signal on the power line after coupling, frequency selection and amplification, and then to decode the state of the controlled electrical appliance after address decoding.
5.1 Power Line Carrier Demodulation Circuit Ground the 5 pins of LM1893 in the typical application circuit of LM1893 and set it to the receiving signal state, just connect the external decoder chip PT2272. The power line carrier demodulation circuit is shown in Figure 6.
The frequency-modulated signal transmitted by the power line is amplified by frequency selection and demodulated by the LM1893. The demodulated signal is output to the decoder PT2272 by the 12 pins of the LM1893. If the A0 ～ A5 address input status of the prepared PT2272 is completely the same as the address status set by the transmitter PT2262, the receiving and sending addresses match, so that the signal can be correctly decoded by the PT2272 after demodulation, and the VT becomes high, indicating that the transmission is valid. PT2272 outputs the same four-bit control codes D0 ～ D3 as the transmitter to the address discrimination and execution circuit to control the switch status of the electrical appliances.
5.2 Address discrimination and execution circuit The address discrimination and execution circuit is shown in Figure 7. The address decoding adopts the high-speed TTL4 ~ 16 line decoder 74HC154, and its input A ~ D end is connected with the control code D0 ~ D3 output from the decoder PT2272. The CP end of the D flip-flop 74HC74A is connected to 10 output ends ("0" to "9") of the decoder representing the address code of the appliance. When the keyboard keys of 0-9 are pressed, the output level of the decoder is effective. If the address code of the controlled electrical appliance entered on the keyboard is the same as the preset address of the dial switch SW-10 of the controlled unit (dial switch Set the address number of the controlled appliance), the high level connected to the D terminal of the D flip-flop will appear on the Q terminal, then Q is low, making the decoder output terminals Y10 and Y11 ON and ON The OFF command can activate the relay through two OR gate circuits to control the switch of the electrical appliance. If the address code entered on the keyboard does not match the address set by the DIP switch, the CP of the D flip-flop is invalid. At this time, Q remains high, the OR gate is disabled, and the ON / OFF command is invalid. When the ALLON (Y12 terminal output) command or the ALLOFF (Y13 terminal output) command is valid, the Q terminal of the R-S flip-flop can be set to 1 or 0 through the AND gate, regardless of whether the OR gate is open. To realize the group control function of fully open or fully closed.
6 Conclusion This article introduces a home appliance network control system that uses power lines as the communication medium. The main control unit is a centralized controller of household appliances with small size, low power consumption and convenient portability, which realizes remote switch control of multiple household appliances (rice cookers, electric lamps, etc.). The controlled unit is a plurality of receiving sockets matched with the home appliance centralized controller, and the address number of the connected electric appliance is set on the dial switch on the socket, thereby forming a home appliance networking remote control system. The system is easy to install and use, with stable and reliable performance, but the scope of use is limited to the same distribution transformer, and the effect of in-phase transmission is the best. Out-of-phase transmission requires a 600V, 1μF withstand voltage capacitor to be connected to the phase line to provide a signal path. The main disadvantage of this system is that the communication transmission distance is limited, currently only 500m is best. If you want to achieve practicality, there is a special advancement to increase the communication transmission distance.
references
1 Zhang Youde, etc. The principle, application and practice of single chip microcomputer. Shanghai: Fudan University Press. 1992
2 Wang Furui et al. Design of single-chip microcomputer measurement and control system. Beijing: Beijing University of Aeronautics and Astronautics Press. 1998
3 Zhang Yuanzheng. High frequency power line communication. Beijing: Water Power Press, 1983
4 NaTIonal Semiconductor CorporaTIon. Linear Data Book. 1992
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