In recent years, electronic information technology has been constantly updated and improved. Smart home is gradually accepted by people.
The application of remote control technology of household appliances is more and more extensive. Based on the author’s years of work experience, this paper analyzed the single chip AT89C51 and some other precision equipment combined with the corresponding software development and design, in order to achieve remote control of household appliances. With the rapid development of telecommunication industry and the improvement of telephone network, the intellectualization of household appliances has gradually infiltrated into people’s living environment. Through the remote control of telephone, various data of household appliances can be collected in real time, and the household appliances can be intellectually controlled by setting instructions. At present, the remote control system of telephone has become more and more popular. Mature, under the voice prompt of users, to achieve fast, convenient, full-time control of the electrical equipment in the family, can also reduce electromagnetic pollution, improve the quality of life, and bring users a better life experience. Usually, there are two kinds of remote control system for household electrical equipment. The composition of remote control system mainly includes: the whole electronic circuit controlled by CPU; when the telephone rings and detects the line, real-time analog hang-up circuit should be included in the circuit, which should also include some automatic hang-up transmission lines and DTMF audio decoding auxiliary lines. The equipment cooperates with each other to connect some important lines such as control lines and power lines. The overall framework of the system is shown in Figure 1. Under the working condition of the system, the internal working principle of the remote control system is as follows: after the telephone is put in, the internal line of the telephone is detected by itself, and there is a direct detection of ringing in the internal system of the telephone. When the number of ringing reaches the set value, the controller starts to work, and carries out the input of password and program, and through the lifting of the line in the system.
Indicate feedback, however, after the digital signals of some internal systems are transmitted to each other, they are transmitted to auxiliary devices, which decode DTMF and translate the digital signals through decoding. After receiving and confirming the decoded digital signals, they are transmitted to the CPU.
When the devices input the signals through the decoded passwords, the system Password is stipulated, but it can not be guaranteed when the number of password input exceeds the prescribed number. Normally, it can not be more than three times. To ensure that the password input is correct, the digital signature of the business approval operation can technically guarantee that this operation can only be operated by the approver, but not by other people. The AC ringing signal which can not be detected is directly converted into the DC signal which can be detected. Usually, the voltage of power supply equipment on many lines is almost 48V, but the supply voltage of some old equipment is very different. They supply 60V. When diodes V1, V2, V3 and V4 rectify each other, V5 which can’t be turned on will be stabilized. At this time, there is little voltage in the ringing signal, or when the ringing signal is generated, The voltage on the transmission line is close to more than 80V. After rectification by V1, V2, V3 and V4, the AC ringing signal is directly converted into DC pulsating signal.
This result often leads to the increase of peak instantaneous time, which leads to the breakdown of V5 instantaneously. The output voltage of ringing will increase with the increase of R1. R1 has a very strong effect on charging C1.
In order to protect the CPU, thermostatic element some measures are needed, such as adjusting the ring signal in the regulator and adjusting the amplitude according to the CPU window, but not exceeding the maximum value of the CPU window. The working principle of OTMF auxiliary circuit is to remotely control the transmitted signals. For example, DTMF signals are sent out according to telephone keys, controlled remotely, and received by MT880 after a series of measures such as capacitance, filtering and straightening of internal components. After receiving, the hardware can be translated to transmit the next work. The output signal is transmitted in binary mode, and the output four-bit data can be directly connected with AT89C5124 MCU. The connection port is P1.0-P1.3. The later data is analyzed according to DTMF data received by MT8870. After correctly analyzing the data, the interface will be cut off and the CPU data will be communicated. All the data in No. 1 is taken away. Here, the P1 terminal is designated as the CPU data interface, and the data is stored in the fixed registry component, which is R7. At this time, the read-in value will be judged, together with the transmission command of the remote controller. This process is the operator’s transmission command. It can save the password of the whole system quickly and change it conveniently. According to the analysis of the circuit diagram of the hang-up machine, when the telephone is hanging up, the line connected by the telephone is open, because at this time, the two telephone lines are connected, and the voltage of both phones is 48V.
The voltage in the line is at both ends of the ring circuit. When the telephone is picked up, the ring line will be disconnected immediately.
At this time, the telephone line will be connected. In the process of telephone dialing, the user needs to confirm the number first, and through the detection of the ring detection line, and form a special pulse signal transmission, which is received by the interface of the single chip computer.
Once the number of rings reaches the number of rings within the system, the single chip computer carries out the software program through AT89C51. Control, its digital signal is generated low voltage, at this time the signal is amplified, through a series of components for transmission, so as to ensure that the triode reaches saturation state, through this internal digital signal and relay cooperation, generate voltage, and install resistance in the line to ensure the smooth connection of the telephone.
Language prompt circuit is realized by ISD4004A voice chip, which has many advantages such as repeated recording and playback, self-contained memory and simple use. ISD stores different voices in the corresponding address by address mode.
At this time, the voices needed by MCU need to be adjusted. According to different control modes, the addresses of different terminals are selected, and the chip terminal is triggered to play the voice immediately. The central processing unit of the system is AT89S52. When the system is powered on and reset, the CPU can continuously detect the status of the ringing signal. Once an effective ringing signal is detected, the system will immediately start the counting program. When the set number of times is counted, the CPU automatically sends out the off-hook data, and controls the off-hook prompt sound from time to time, prompting the user to complete the password input. The remote control of household appliances will be more and more widely used in family life and play an important role in China’s economic construction.
Promoted by the development of information network, the telecontrol of household appliances by telephone no longer needs too much wiring, and the automatic collection of information is becoming more and more mature. By adopting reasonable ways and management means, we can realize remote control of household appliances. At the same time, we should constantly sum up experience and improve methods to further strengthen the healthy and stable development of information technology in China.