Abstract
Along with the widespread use of telephone in family, the remote control of household appliances by means of telephone is to be realized in the future. This paper introduces a remote control system of household appliances through telephone line, based on 89S51 MCU and MT8880 integrated circuit. This remote-control system contains five functional modules: password set-up, number-display, speech hint, signal decoding, and control button. With an overall function of being practical, flexible, and easy for operation, the respectively independent modules which are easy for modification and function expansion can be used in various control devices in household appliances and electric equipments of other places. The paper gives a detailed description of various functional modules, including the circuit working principles of telephone bell examination and phone-connection simulation, DTMF signal and MT8880 processing, the structure of memory chip 24C02 and its way of working, button processing, and number display. In addition, the paper explains in detail the calculation of parameter, imitation of electric circuit, debugging of hardware and software, and programming.
Keywords:Dual Tone Multi Frequency; speech hint; telephone bell examination; phone-connection simulation