A programmable telephone rate meter: a hardware/software codesign case study

Abstract

We present an example of the design of an embedded digital system using hardware-software codesign methodology. The use of this methodology permits a relatively inexperienced digital designer to develop a reasonably sophisticated device consisting of a microprocessor and custom hardware in a very short time. The device under production is a telephone rate meter that keeps track of the cost of calls made from a particular telephone. Given the plethora of calling plans marketed by telecommunications providers, a great deal of flexibility is required in the manner in which the rate structure can be specified. Use of codesign methodology permits the metering of any rate structure that can be specified algorithmically.