St. Louis, Missouri
June 18, 2000
June 18, 2000
June 21, 2000
5.523.1 - 5.523.8
Remote Control of Microcontrollers with a Telephone
Chong Chen and Jack Crotty Department of Engineering Technology and Industrial Studies Middle Tennessee State University Murfreesboro, TN 37132
Computer network technology has developed rapidly in recent years. A person may contact another person in any part of the world through a computer network. A person may also control the operations of a computer at a remote location through a computer network. Each of these requires access to a computer linked to a computer network.
This paper presents a low cost, simple system to control a microcontroller over a phone line. Any touch-tone phone can be used for sending commands to the microcontroller. A computer and computer network access are not needed for this remote control. The system allows one to operate a microcontroller and control other equipment connected to the microcontroller from any touch-tone telephone.
This remote control system includes an answering machine, a signal detecting and decoding circuit, and a Motorola 68HC812 microcontroller. The answering machine works like a regular answering machine, which answers calls and records messages. The control commands are entered by pressing a telephone keypad. The password, start command, and other control commands are comprised of different predetermined keypad signal sequences. The detecting and decoding circuit monitors the incoming phone signals and sends the decoded keypad signals to the microcontroller. When a start command is detected, the microcontroller takes over the phone line and signals the answering machine to drop off the line. Then, after detecting a correct password, the microcontroller accepts the incoming commands from the phone line. Following these commands, the microcontroller may send signals to operate other connected equipment, such as air conditioning, or security system of a building. It may also send requests to other computers.
With the development of local area networks, wide area networks, and the Internet, people can easily operate remote computer systems. The distance between the computer and the operator is no longer measured in feet, and could be hundred or thousand miles. To communicate with a computer network, the operator usually needs another computer linked to the network. Figure 1 shows a computer network . Any computer in the network may send information to, or receive information from, any other computer in the network.
Crotty, J., & Chen, C. (2000, June), Remote Control Of Microcontrollers With A Telephone Paper presented at 2000 Annual Conference, St. Louis, Missouri. https://peer.asee.org/8661
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