Intermediate C Programming for the PIC Microcontroller: Simplifying Embedded Programming

This book looks at some useful aspects of the PIC microcontroller. It explains how to write programs in C so that you can use the PIC micro to control a variety of electronics and DC motors. After reading this book, you will be well on your way to becoming an embedded programmer using the C programming language. The Aims and Objectives of This Book The main aim of this book is to introduce you to some useful applications of programming PIC micros such as • Creating header files • Controlling seven-segment displays • Using an LCD display with two lines of 16 characters • Pulse width modulation • Using driver ICs such as the ULN2004A • Controlling DC motors, including stepper motors and servo motors • Using every aspect of the Capture, Compare and PWM, CCP module in the PIC • Using interrupts • Writing to the EEPROM Another useful piece of software is a suitable ECAD (electronic computer-aided design) software program that supports 8-bit micros. The ECAD software I use is PROTEUS. However, it is not free, so as well as showing you how to simulate the programs in PROTEUS, I will show you how to use a suitable prototype board to run the programs in a practical situation. If you want to go down the practical route, you will need to purchase a programming tool and a prototype board. The tools I use are either the ICD3 can (Microchip has now moved onto the ICD4 can) or the PICkit3 programmer to download the programs from MPLABX to the PIC. The prototype board I use is the picdem2 plus DEMO BOARD and a prototype board from Matrix Multimedia (although Matrix no longer produces the more versatile board that I use). This book was written based around using MPLABX V5.25. However, the principles of how to create projects and write programs are transferable to earlier and later versions of MPLABX. There may be some slight differences in the details, but they shouldn't cause too many problems. The PIC that this book is based around is the PIC18F4525. This is a very versatile 8-bit micro that comes in a 40-pin dual-inline package. As long as the PIC you want to use has the same firmware modules, then the programs in the book can easily be used on other PIC micros with some minor modifications. However, you should always refer to the data sheet for the particular PIC you use because some of the SFRs (special function registers) may differ. For example, the PIC18F4525 uses the ADCON0, ADCON1, and ADCON2 SRFs to control the ADC module but the 16F88 uses the ANSEL, ADCON0, and ADCON1 registers. Throughout the book, I include program listings and I go through an analysis of any new instructions that the listings introduce. With respect to the first listing, I will assume that all of the instructions are new to you, the reader. Before we move into the book for real, I think it will be useful to you if I explained a bit about what MPLABX is. It is an industrial IDE created by Microchip. The term IDE stands for integrated development environment. It is actually a lot of programs collected together to create a programming environment: • There is an editor, which is slightly more than a simple text editor. However, in my early days, I used to write my programs in Notepad. • There is also a compiler program that converts your program instructions from C to the machine code that all microprocessor-based systems use. In the very early days of programming, the programmers used to write in this machine code. This was a bit before my time, although in my early days, I wrote all my programs in assembler. Assembler is the closet language to the actual machine code that all micros use. • There is also a linker program that will bring together any include files that we wish to use in our projects. • As well as these programs, there are a range of programs that we can use to help debug our programs or simply simulate them. So this IDE is a very large collection of programs that make our job of writing code much more efficient. Yet it’s free; well, I use the free version, which is not as efficient as the paid version but it is more than good enough for us. I therefore hope that you not only learn how to program the PIC micro but you also enjoy going through my book and that you produce some useful projects along the way.