Telephone Remote Control Home Appliances

By using CCITT and SPC exchange order of Chinese standard as system control order and PLMN & PSTN as transmitted medium, the Intelligent Telephone Remote Control System (ITRCS) can realize the remote control to the household appliances, which makes the fixed phone or mobile phone send the DTMF signals. According to this idea, we designed and implemented a telephone remote control system with the single chip of AT89S51, the DTMF decoder of MT8870, EEPROM of AT93C46. The main works are as follows:1. Study the control mode available for the household appliances. Considering commonality, flexibility, cost and complexity of hardware, telephone is selected as the controller to realize the control of household appliances.2. Study the work modes of telephone. Sum up the DTMF principle of telephone dialing, and get the advantages of DTMF. Then, the chip MT8870 is chosen as the decoder circuit, which has high precision and good stability.3. Study the theory, interface and application of single chip, and compare the capability of single chip in common use. According to program data quantity, interface circuit, hardware and capability of anti-jamming, we select AT89S51 single chip as the core of controller.4. In order to reduce peripheral elements and improve the circuit stability, we apply talk-IC (MC34014), and use IC normal peripheral circuit during the design of main circuit.5. After the design and test of the hardware, the PCB board is implemented.6. Design the software based on the hardware circuit.In the end, the design can fulfill the following functions: 1) Remote control of air conditioner, 2) Password protection to prevent mis-operation, 3) Password can be modified with protection of power off, 4) Field control function, 5) The control function can be changed by simple wiring.