Software for Eight-Bit Microprocessors in Multivariable Digital Control Systems

Abstract

This paper compares computer programs implementing linear multivariable digital control algorithms written in high level and assembly languages for eight-bit microprocessors. The execution speeds of the programs are compared for fixed-point and floating-point formats for controllers of increasing order, with faster speeds allowing greater achievable controller sampling rates. Methods are presented for optimizing the high level language programs using in-line assembly code in critical program modules and performing floating-point computations on a dedicated arithmetic function processor. Quantitative results are presented for achievable sampling rates as functions of the order of the controller, the number of inputs and outputs, language level used for the control program, and optimization method. Design guidelines are given for development of controller software for different applications.