Asee peer logo

Remote Control Of Microcontrollers With A Telephone

Download Paper |


2000 Annual Conference


St. Louis, Missouri

Publication Date

June 18, 2000

Start Date

June 18, 2000

End Date

June 21, 2000



Page Count


Page Numbers

5.523.1 - 5.523.8

Permanent URL

Download Count


Request a correction

Paper Authors

author page

Jack Crotty

author page

Chong Chen

Download Paper |

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Session 1647

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 [1]. 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.

ASEE holds the copyright on this document. It may be read by the public free of charge. Authors may archive their work on personal websites or in institutional repositories with the following citation: © 2000 American Society for Engineering Education. Other scholars may excerpt or quote from these materials with the same citation. When excerpting or quoting from Conference Proceedings, authors should, in addition to noting the ASEE copyright, list all the original authors and their institutions and name the host city of the conference. - Last updated April 1, 2015