Non Portable C Language For Microcontroller Applications

A previous goal of the microprocessor/microcontroller class in the Buffalo State College Engineering Technology Program was to develop proficiency with an assembly language in order that students could write assembly language code for various microprocessors and microcontrollers. The goal has been modified such that students become familiar with assembly language programming as well as understanding the role of a high-level language such as C in microcontroller applications. Concepts of portability, variable storage space, and hardware registers are presented to help students understand the strengths and weaknesses of programming a microcontroller with highlevel language such as C. A high-level language brings features like loops, arrays, and decisionmaking capability to the very rudimentary assembly language. Standard C languages such as ANSI C are portable, meaning they are independent of the microcontroller that will ultimately be used to execute the code. However, to best utilize the microcontroller for digital I/O and timing delays as well as many other tasks, read and write access to the specific hardware registers of that microcontroller are needed and therefore portability must be sacrificed. In this case, a "special compiler" is required that recognizes the specific hardware of the microcontroller. An example of such a compiler is the Rigel Corporation 8051 C compiler, which provides two methods for communicating with specific hardware in the 8051 Note: Microcontroller will refer to both microcontrollers and microprocessors in this paper.