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Written with the beginner in mind, this project-oriented guide gives you twelve
complete projects, including: add sensing abilities to robots, build decision-making
neural and "fuzzy logic" functions into your projects, convert any analog signal
to digital, deliver messages on a LCD, synthesize human speech, control DC motors, stepper
motors, and servos, read resistive sensors for robotics applications, build a frequency
generator, make a DTMF phone number logger and distinct ring detector and router, build a
digital oscilloscope, and home automation using X-10 communications.
Excerpt:
Chapter 1: Microcontroller
What Is a Microcontroller?
A microcontroller is an inexpensive single-chip computer. Single-chip computer means
that the entire computer system lies within the confines of the integrated circuit chip.
The microcontroller on the encapsulated sliver of silicon has features similar to those of
our standard personal computer. Primarily, the microcontroller is capable of storing and
running a program (its most important feature). The microcontroller contains a CPU
(central processing unit), RAM (random-access memory), ROM (read-only memory), 1/O
(input/output) lines, serial and parallel ports, timers, and sometimes other built-in
peripherals such as A/D (analog-to-digital) and D/A (digital-to-analog) converters.
Why Use a Microcontroller?
Microcontrollers, as stated, are inexpensive computers. The microcontroller's ability to
store and run unique programs makes it extremely versatile. For instance, one can program
a microcontroller to make decisions (perform functions) based on predetermined situations
(1/O-line logic) and selections. The microcontroller's ability to perform math and logic
functions allows it to mimic sophisticated logic and electronic circuits.
Other programs can make the microcontroller behave like a neural circuit and/or a
fuzzy-logic controller. Microcontrollers are responsible for the "intelligence"
in most smart devices on the consumer market.
The Future of Electronics Is Here-It's Microcontrollers
Look in any hobbyist electronics magazine from this country or any other. You will see
articles that feature the use of microcontrollers, either directly or embedded in the
circuit's design. Because of their versatility, microcontrollers add a lot of power,
control, and options at little cost. It therefore becomes essential that the electronics
engineer or hobbyist learn to program these microcontrollers to maintain a level of
competence and to gain the advantages microcontrollers provide in his or her own circuit
designs.
If you examine consumer electronics, you will find microcontrollers embedded in just about
everything. This is another reason to become familiar with microcontrollers.
Designer Computers
There is a large variety of microcontrollers on the market today. We will focus on a few
versatile microcontroller chips called PIC chips (or PICMicro chips) from Microchip
Technology.
The PIC Chip
Microchip Technology's series of microcontrollers is called PIC chips. Microchip secured a
trademark for the name PIC. Microchip uses PIC to describe its series of PIC
microcontrollers. PIC is generally assumed to mean programmable interface controller.
Better Than Any Stamp
Parallax Company sells an easy-to-use series of microcontroller circuits called the Basic
Stamp. Parallax's Basic Stamps (BS1 and BS2) use Microchip Technology's PIC
microcontrollers. What makes the Stamps so popular and easy to use is that they are
programmed using a simplified form of the Basic language. Basic-language programming is
easy to learn and use. This was the Stamps' main advantage over other microcontroller
systems, which have a much longer learning curve because they force their users and
developers to learn a niche assembly language. (A niche assembly language is one that is
specific to that company's microcontroller and no one else's.)
The Basic Stamp has become one of the most popular microcontrollers in use today. Again,
the Basic Stamp's popularity (this bears repeating) is due to its easy-to-learn and
easy-to-use Basic-language programming. The PIC's Basic language system is just as easy to
learn and use, and the PIC has enormous benefits that make it better than any Stamp.
The Basic language of the PICBasic compiler that we will use to program the PIC chips is
similar to that used in the Basic Stamp series. Programming PIC chips directly has just
become as easy as programming Stamps. Now you can enjoy the same easy language the Basic
Stamp offers, plus two more very important benefits.
Benefit one: faster speed
Our programmed PIC chips will run their program much faster. If we enter the identical
Basic program into a Basic Stamp and into a PIC chip, the programmed PIC chip will run 20
to 100 times faster (depending upon the instructions used) than the Basic Stamp. Here's
why.
The BS1 and BS2 Basic Stamp systems use a serial EEPROM memory connected to the PIC chip
to store their programs. The basic commands in the program are stored as basic tokens.
Basic tokens are like a shorthand for basic commands. When running the program, the Basic
Stamp reads each instruction (token and data/address) over the serial line from the
external EEPROM memory, interprets the token (converts token to the ML equivalent the PIC
can understand), performs the instruction, reads the next instruction, and so on. Each and
every instruction goes through these serial load, read, interpret, then perform steps as
the program runs. The serial interface reading routine eats up gobs of the
microcontroller's CPU time.
In contrast to this operation, when a PIC chip is programmed using the Basic compiler, the
Basic program is first converted to a PIC machine language (hex file) program. The ML
program is then uploaded into the PIC chip. Being the native language of the PIC, this
machine-language (ML) code does not need to be stored as tokens and interpreted as it runs
because the program is written in the PIC chip's native language.
When the PIC chip runs the program, it reads the ML program instructions directly from its
on-board memory and performs the instruction. There is no serial interface to an external
EEPROM to eat up CPU time. The ML instructions are read in parallel, not bit by bit as in
the serial interface. The ML instructions read directly without any
basic-token-to-ML-equivalent conversion required. This enables programmed PIC chips to run
their code 20 to 100 times faster than the same Basic program code in a Basic Stamp.
Benefit two: much lower cost
The next factor is cost. Using PIC chips directly will save you 75 percent of the cost of
a comparable Basic Stamp. The retail price for the BS1, which has 256 bytes of
programmable memory, is $34.95. The retail price for the BS2, which has 2K of programmable
memory, is $49.95. The 16F84 PIC microcontroller featured throughout this book is more
closely comparable to the BS2 Stamp. The 16F84 PIC chip we are using has 1K of
programmable memory.
The retail cost of the 16F84 PIC chip is $6.95. To this, add the cost of a timing crystal,
a few capacitors, a few resistors, and a 7805 voltage regulator to make a circuit
equivalent to that of the Stamp. These components increase the total cost to about
$10.00-still well below one-quarter the cost (75 percent savings) currently quoted for the
BS2...
Table of Contents:
Chapter 1. Microcontroller.
Chapter 2. Software Installation (Compiler and Programmer).
Chapter 3. PIC16F84 Microcontroller.
Chapter 4. Reading I/O Lines.
Chapter 5. PICBasic Language Reference.
Chapter 6. Characteristics of the 16F84 Microcontroller.
Chapter 7. Speech Synthesizer.
Chapter 8. Serial Communication and Creating I/O Lines.
Chapter 9. LCD Alphanumeric Display.
Chapter 10. Sensors: Resistive, Neural, and Fuzzy Logic.
Chapter 11. DC Motor Control.
Chapter 12: Stepper Motor Control.
Chapter 13. Servomotor Control.
Chapter 14. Analog-to-Digital (A/D) Converters.
Chapter 15. Controlling Ac Appliances.
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