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Automation in Construction [J]. : 529540附錄附錄1 外文資料Design of a Telephone Remote Controller Guangli Long School of Physics and telemunication Engineering,Shaanxi University of Teology,Hanzhong ,China,lgl20088@ Abstract Electrical equipments are remote controlled through the telephone,a remote controller based on the fixed telephone line was designed by using MCU and DTMF controller includes hardware and software ,hardware are posed of MCU minimum system,ringing detection circuit,simulation of offhook and onhook circuit,driving circuit of electrical equipment,decoder of DTMF, LCD,keyboard and EEPROM etc.。software are posed of main program, countting the number of ringing program,DTMF decoding program,keyboard scanning program,voice program,EEPROM reading and writing program,displaying program,etc..The software programmed with C language, it is piled on Keil C51 platform and produced the HEX file and downloaded to the MCU hardware circuit is simulated on the Proteus board of PCB is designed and manufactured,The MCU and other electronic ponents are welded on the PCB .It is connecting with the line of fixed telephone, when the telephone number was called,the electrical equipment may be controlled to turn on or turn off,the password is showed on the LCD,the tip of voice is played.Keywords: Telephone ,Controller, Electrical equipment,MCU 1. Introduction With the development of economy and science technology, people39。s living standard is getting higher and higher, more and more electrical equipment, such as the induction cooker, electric rice cooker,refrigerator, TV, puter etc.. Mostly manual or short distance remote control switch, not remotely close or open. When going out people may forget to turn off the lights, turn off the puter, Pull plug electromagnetic stove etc.. when think of it , people might have been far away from home. Telephone remote controller can effectively solved this problem, it will appliances connected to the output end of the controller, the controller is connected to the telephone line, Electrical equipments are remote controlled by using the telephone line. when the telephone number was called,the electrical equipment may be controlled to turn on or turn off,the password is showed on the LCD,the tip of voice is played. 2. Design of hardware The block diagram of the telephone remote controller is showed in Figure 1, it consists of the MCU minimum system, ringing detection circuit, simulation offhook circuit, decoding of DTMF circuit, voice recording circuit, display circuit, the keyboard matrix, memory unit and driving circuit of electrical equipment,etc.. The block diagram of the telephone remote controller Design of the MCU minimum system The minimum system of the MCU are posed of MCU AT89S52, clock circuit, reset circuit and the programming interface, Its main function is to control for each module. The reset circuit with manual reset and reset in two ways, the crystal is . In order to download the program to the MCU, the ISP programming interface which support the MCU AT89S52 is specially selected, the download circuit is designed according to the programming interface requirements. In order to make the programming interface can reuse and other device port, the download interface and matrix keyboard multiplexing approach is taken to I/O port, not to press the keyboard when download, the download line is plugged after download, it will not have any effect on the system. Design of the ringing detection circuit The ringing detection circuit is designed as shown in Figure 2, the ringing signal is based on 48V DC voltage superimposed on the peak value of 90V/25Hz sine wave signal, and the ringing signal every 4 seconds to send 1. Ringing detection circuit isolate the 90V sine wave signal, and converted to square wave signal which peak is 5V/25Hz, This signal is sent to the MCU counting. By limiting stepdown approach, the optocoupler is no output when the input is less than 50V , and obtained the positive half cycle of sine wave signal when the input is greater than LM339 is used to do the parator which sine wave signal is converted to a standard square wave cycle, calculation of the ringing signal by MCU to determine whether the ringing signal 25Hz. The 27V zener diode is used for depression in figure 2, in order to prevent the optocoupler current is too large to burn out. R12 is a current limiting resistor, when the ringing signal arrived, the 25Hz halfwave sinusoidal signals is generated through the output of optocoupler. It is obtained the value of by paring the values of the two resistor in the inphase end of parator, when the ringing signal does not e, the reverse input is 0V, then the output is high, when the ringing signal arrives, through the optocoupler isolation, the reverse output is 5V/25Hz half sine wave, when the reverse voltage is more than ,the output of parator is 0V , the peak of 5V/25Hz square wave signal is sent to the MCU counting. Fig. 2 The ringing detection circuit Design of analog offhook and telephone interface circuit Design of analog offhook and telephone interface circuit as shown in figure 3. The circuit is mainly posed of a telephone li