INTRODUCTION TO
ROBOTICS
Part 5: Programming
Robotics and Automation
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1
“We live in a society exquisitely
dependent on science and technology,
in which hardly anyone knows
anything about science and technology”
– Carl Sagan, 1990
This statement was made before the Internet and
cell phones. It has only become worse since then.
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2
Technology and Computers
• Technology has become very easy to use.
• But just beneath the surface, most technology
is incredibly complex.
• Computers are literally the most powerful
problem-solving tools humanity has
ever created.
• We all benefit when the knowledge of how to
apply those tools is more widely understood
in our society.
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3
Coding and Solving Problems
• The ability to code is not just a way to
understand technology.
• The ability to code is a mode of thought
and a language in itself—the same as
literacy or mathematics.
• Coding involves critical thinking, problem
solving, analysis, and logic. It is not about
writing code; it is about solving problems.
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4
It is time to open up
the black box!
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5
Program Requirements
Programming requires
• Something that will run the program
oA computer
oA microprocessor
oA microcontroller (what we will use!)
• A computer program that lets a user write a
computer program
oAn IDE
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Integrated Development Environment
• A computer program used to write a computer program
o Allows students to write a computer program that can be
downloaded from any PC
o Allows users to write code in a language that is easier to use
than the machine level code
• In this case, C and C++
o Converts the higher level language to the machine code that is
specific to a family of microprocessors
o Allows the microcontroller to perform the instructions and to
interact with the outside world
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IDE Components
•
•
•
•
•
•
Editor
Assembler/ Compiler
Simulator
Debugger
Programmer (optional)
Emulator (optional)
An IDE is specific to a device or a family of devices
made by a particular manufacturer.
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8
Choosing a Platform
• Robots require programming and instructions to operate.
o When they face a situation outside of their program, they
can stop, fail, or crash.
• This makes the microcontroller the key piece of a robot.
• There are generic ways of learning about robots, but
generic descriptions can only go so far for teaching.
• With generic descriptions, you reach a limit on the
amount of learning and understanding.
• You need specific examples, and for specific examples we
need to decide on a platform.
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What is a Microcontroller?
• A microcontroller is an entire computer on a chip.
o RAM, ROM, I/O, port controllers, converters, timers, and
CPU are integrated as a single system.
•
•
•
•
Self contained and sometimes on a single chip
Single purpose
Does not require much processing power
The operating system is simple, contained in ROM,
and has a built in instruction decoder for the
language used.
• They are relatively simple and easy to use.
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10
Microcontrollers
• The world is becoming increasingly electronic, so
some type of understanding about how electronics
actually work is becoming more important.
• One of the key advantages of a microcontroller is
that people can program and use them.
• Microcontrollers go beyond theory because one can
quickly enable them to produce the same real world
outputs seen everyday.
• At the same time, there is a depth to microcontroller
knowledge and application that is virtually unlimited.
• They can be used to create more powerful
applications than the individual circuits alone.
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Choosing a Microcontroller
We compile a list of features and criteria we want.
o
o
o
o
o
The microcontroller’s cost must be low while including a
development board (below $50).
It must be easy to use and well supported. It is important to
have a lot of documentation readily available.
It should be programmed in a useful and common language.
It must be popular and have an active user community.
Since the robot will be used as a general purpose platform, the
microcontroller should be very feature rich in order to allow for
broad experimentation. In this sense, it should have several
analog and digital pins, as well as an integrated
voltage regulator.
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Choosing a Microcontroller
• There are many fine examples of microcontrollers to
choose from.
• There are a number of very good and popular high-level
programming languages including C, C++, C#, Basic,
and more.
• Taking all these factors into consideration, one should
choose a microcontroller that
o is inexpensive,
o uses the C programming language, and
o has a variety of inexpensive and available add-on boards.
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13
Open Source vs. Proprietary
• Choose hardware and software that are open source,
which means
o the boards are inexpensive and
o the software is simple and flexible.
• Choose open-source technology with a list of public
domain resources including
o libraries,
o working examples, and
o experienced programming support.
• Proprietary software and hardware is controlled,
limited, and expensive.
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Why Not a PC?
• A PC is expensive
o hundreds of dollars vs. $30
• A PC uses a lot of electrical power
o 600 W vs. < .5 W
• A PC is not portable
o uses AC not DC
o is heavy and bulky
• A PC requires many peripheral components
o keyboard, mouse, RAM, monitor, hard drive
• Many different types of connections to make
o SATA, PATA, PCI, PCIe, VGA, USB, serial, parallel
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Microcontrollers vs. PC
• One of the key features of PC
microprocessors is that they have to be
backward compatible
o This adds to expense and complexity
o Motherboards in particular are complex
and expensive
• Microcontrollers have fewer and
simpler connections
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16
Applied Programming
• Start with a simple example
• Interface a simple device to the
microcontroller
• The computer program provides
that interface
• Combine physical, electrical,
and software
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Back to the Bumper Switch
• A bumper switch produces an output voltage
whether it is open or closed.
o Zero volts is recorded as a binary zero (false).
o +5 volts is recorded as a binary one (true).
• The values are stored as a variable.
• A program loop reads the variable value
thousands of times per second.
• The true or false conditions are evaluated by
the conditional loop.
• A program function is executed either way.
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18
The Worlds Simplest Program
void setup() {
// put your setup code here, to run once;
}
void loop() {
// put your main code here, to run
repeatedly;
}
This program has every required element
needed to run in a microcontroller, with proper
syntax and formatting. However, it will not actually
do anything constructive.
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19
Program Parts
The first thing to notice is the program has two parts
• A part that runs once
• A part that runs over and over again
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Syntax
The next thing to notice is the use of formatting
symbols in the program. These symbols form what is
called the syntax, which is the language the
program uses.
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Syntax
• Each symbol has a particular meaning.
• Some of the symbols are required for the
program to be compiled and executed
correctly.
• Others define parts of a program such as
statements and functions.
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Symbols
• Braces { }, or curly brackets, go around
executable program sections called
functions.
o Both an opening brace (or left brace) and a
closing brace (or right brace) are needed.
• The semicolon ( ; ) ends a program
statement or command.
o An easy way to get a syntax error is to forget
to use a semicolon after a command.
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More Symbols
• The parenthesis after each instruction is
required and tells the program that the
name used is a function and not something
else.
o A variable
• The word “void” tells the program that the
functions setup () and loop () do not return
any values or data.
o This word is required or the program will hang
up waiting for data.
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24
Keywords
• Keywords are words and names that are already
defined in the C++ language to perform specific
operations.
o They must be used correctly for the program to
work at all.
o Failure to use symbols and keywords correctly
results in something called a syntax error.
• You can define your own keywords.
o They must be defined before you use them in
a program.
o It is done by naming a procedure.
o It creates what is called an abstraction.
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25
Abstractions
• The main purpose of this part of the lesson is
to introduce functions, statements, loops,
variables, comments, and the formatting
symbols that make up the syntax.
• We will use abstractions in our programming
examples.
• This is done primarily to simplify the
program.
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26
Example Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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27
Variables
• A variable must be defined before you can use the
variable (example: to store or read data), during
initialization, before the main program loop.
• Anytime you have a condition to evaluate you
have data.
• Data requires a name and a memory location.
o Defining a variable does both of those things.
• Data size is both how big the number can be and the
amount of memory used to store it.
o Char = 8 bits (0-255), int = 16 bits (0-65,535)
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28
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
Assign variables
Int = 16 bits
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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29
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
We//value
like to use names
for our pins
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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30
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
And for our data
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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31
Program Loops
• A program (or program segment) that runs
the same section of code over and over
• Necessary when waiting for an input while
performing other tasks like
o generating video while waiting for user input,
o driving around until bumping into an object, or
o performing a particular task only when a
specific condition is present.
• Most programs involve one or more loops
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32
Types of Loops
• Infinite loops
o Usually the main program loop
o Can also be the result of a programming error
o Example: while
• Counting loops
o Performs an action a specified number of times
o Example: for
• Conditional loops
o Performs a specific action as a result of a
specific input
o Example: if, else
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33
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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34
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
These are comments
}
(not executed)
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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35
Program Description
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
These are
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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statements
36
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as anStatements
input:
are
pinMode(switchPin, INPUT);
computer commands
}
terminated with a
void loop() {
semicolon ( ; )
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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37
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
These are called
}
functions
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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38
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
Functions are
}
enclosed in brackets
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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39
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
Functions are
}
enclosed in brackets
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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40
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
Do the stuff in this
}
function once
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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41
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
We want to set pin 7
}
as an input
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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42
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
Do the stuff in this
}
function over and
void loop() {
over again
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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43
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
Get the value on pin
pinMode(switchPin, INPUT);
7 many times as we
}
drive around
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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44
Improved Program
int switchPin = 7;
int switchdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read the state of the pushbutton value:
switchdata = GetDigitalInput(switchPin);
}
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45
Second Example
• What if we want to read data from an
analog sensor?
• An analog sensor has many values over a
range, such as temperature.
• We only need to change a few
commands from the previous example.
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46
int analogdata = 0;
Use a new name
analogdata = GetAnalogInput (7);
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47
int analogdata = 0;
analogdata = GetAnalogInput (7);
Use a different command
to read analog data
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48
Analog Data Program
int switchPin = 7;
int analogdata = 0;
// the number of the pushbutton
//pin
// variable for reading the switch
//value
void setup() {
// initialize the pushbutton pin as an input:
pinMode(switchPin, INPUT);
}
void loop() {
// read and store the analog value:
analogdata = GetAnalogInput(switchPin);
}
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49
Analog vs. Digital Input
• Not much difference in how you get
the data
• Huge difference in what you can do
with it
• Binary only has two values and you can
only do two things with it
• Analog has many values and you can do
many things
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50
Analog Input
• This means many decisions and
potentially much more complicated
programming.
• Use less than or greater than
mathematics, more than equals.
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51
Learn By Doing
• You have been shown how to get started
in programming.
• From here, the only way to learn is to
learn by doing!
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