Part 5 - PIC16 C Applications and Systems

Abstract

Formal design methods recommended for engineering projects may need to be applied in professional design environment. This chapter outlines some basic methods as a starting point; these allow new applications to be developed with some degree of consistency and help communicate project concepts and design details clearly in reports and presentations. The block diagram is an effective way to show the general form of a microcontroller application design. The block diagram is easily constructed using only the drawing tools in a standard word processor. The application program can be designed using various methods. The software design principles are applied to a typical application, a temperature control system. The process of designing the software can be aided by writing a program outline. The main structures and sequences are summarized using suitable layout and operational descriptions. A general purpose board with a typical selection of peripherals attached to a PIC 16F877A is described. As microcontroller operating programs become more complex, consideration must be given to the best method of organizing the program response to input, memory management, and output timing. Three main methods are used to handle input and output events, which after all, is the primary requirement of a real-time system. In order of complexity, they are I/O polling, interrupts, and the real-time operating system (RTOS). Some relevant factors in the selection of the best combination of hardware, programming language, and development tools for any given microcontroller product design are discussed.