Introduction to Microcontrollers: Arduino

Skylar Roebuck and Lucas Libraro

What we will learn you…• Presentation learnin

– The Arduino– Microcontroller basics– Introduction to programming

• Variables• Binary

– Introduction do the digital ‘1’ and ‘0’

• Data types• Anatomy of a program• Sketches- setup and loop• Logic AND, OR, NOT

– Circuit Construction• What’s in the kit?• Ohm’s Law• Resistor Color Coding• Pull Up and Pull Down

Then we get building…

The Arduino

What is an Arduino

The Arduino is first and foremost a microcontroller.

So what is a microcontroller?

• Essentially, a microcontroller is a small computer on a single integrated circuit.

• The microcontroller has a simple CPU comprised of clock timers, input/output ports, and memory.

Uses:

• automatically controlled products and devices• automobile engine control systems • implantable medical devices • remote controls• office machines• appliances• power tools• And more and more and more

Personal Project Uses:

• Microcontrollers are great at handling inputs and outputs for example:

• Using a temperature sensor and outputting the temperature on a screen.

• Using an infrared sensor and using it to guide a robot by controlling motors.

• Using servos to move a robotic arm• Possibilities are endless.

So why the Arduino?

Vs.

Arduino• Expandability

– Easy to attach Ethernet shields, sensors, etc.

• Easy Setup– All you need is a standard USB cable for programming and power

• Breakout board– Circuit creation is made easy by not having to do any soldering

• Inexpensive

• Powerful– Fueled by the Atmega328 microcontroller

The learnin

Pencils and Paper Time!

Variables

• A variable is how you store a value within a program

• Examples: • Hackrva = “awesome”;

– Assigns the string (a data type) Awesome to hackrva

• Hackrva = 2;– Assigns the integer 2 to the variable hackrva.– Further: hackrva = hackrva + 2;

» NOW: hackrva = 4

Data types

• Data types are an important foundation to programming. For example, if you want a program to count to 10 then you want:– 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

• You do NOT want– 1.00000, 1.00001, 1.00002, etc.

• This is solved by using data types properly

Data types mark 2

• In the example before, counting to 10, we would want that to be an integer so that it ignores all other values.

• This is done in conjunction with the variable and this process is known as defining or initializing variables:

• Int counter;– -this just tells the compiler that counter is an integer and

it doesn’t need to be concerned with any other data.

Data types mark 3

• Further there are many data types and the variable needs to be assigned according to what it will be used for.

Common data types are:• String = “hack.rva rocks”;• Char = “A”;• Int = 1;• Float = 1.5675;

– Binary types• Boolean = 0; (only 0 or 1)• Byte = “00001111”;

The nitty gritty• The foundation of programming is • the ‘0’ and the ‘1’

• Boolean• ‘0’ – No• ‘1’ – Yes

• Binary• 000 - 0• 001 - 1• 010 - 2• 011 - 3• 100 - 4• 101 - 5• 110 - 6• 111 - 7

This is what the microcontroller understands

Seems very polar but there are shades of gray we will discuss later

LOGIC Gates

• Logic comes into play when working and thinking on a binary level. They are essentially operations like +, -, *, / except on a binary numbers.

• In fact using logic is how you CREATE +,-,*,/ well…you also need about 5000 transistors.

• The foundation basic gates are:• AND, OR, NOT

ANDINPUT OUTPUT

A B A AND B

0 0 0

0 1 0

1 0 0

1 1 1

Example: We want LED3 to come on when LED1 and LED2 are both on:

If LED2 = 1 AND LED1 = 1 then LED3 = 1

OR

Example: We want LED3 to come on when either LED1 and LED2 are both on:

If LED2 = 1 OR LED1 = 1 then LED3 = 1

INPUT OUTPUT

A B A OR B

0 0 0

0 1 1

1 0 1

1 1 1

NOT (invert)

Example: We want LED3 to be the opposite of its current state (if off then on and if on then off):

LED3 = NOT LED3;

INPUT OUTPUT

A NOT A

0 1

1 0

Anatomy of a Program

How do we make it do what we want: Program it!

• High level languages– C++, C, Java – closest to natural human understanding– Arduino’s Programming Language

• Low level languages– Assembly Code– a little more difficult to interpret for a person but still

possible

• Lowest (if you write this you have too much free time)– Machine Code – all patterns of ‘0’s and ‘1’s– The microcontroller might see:

0001001010010100101001001010001010101010– And from this it will know a specific command.

A program.

• Basic life of a program:– User writes a program in C (a high level language)– A compiler will then take that code and converts it into

Assembly language– Then an assembler will take that code and turn it into machine

code.

– We are using an Arduino IDE, or integrated development environment, so we will write code using Arduino’s language and it will take care of the rest!

– Easy Peazy

Programming Languages• Obviously, not every programming language is the same. Each language

differs in a way that makes it particularly good for something.

• Arduino is no different. Arduino has been simplified specifically to make it easy to program the Arduino microcontroller.

• Anatomy of an Arduino Program:– Arduino calls every program a Sketch (maybe they feel like that makes them edgy

to be different)– Sketches are comprised of a SETUP and a LOOP section– Setup: Only Runs once and is used to set necessary registers and pins– Loop: This is the rest of the sketch and by default when a sketch finishes in this

language it repeats the entire sketch. Essentially looping-a concept we will cover later.

CIRCUIT CONSTRUCTION

What’s in the kits?

What’s in the kits?Half-sized breadboard- 400 connection points, plenty of room for beginner projects, with 2 power rails on the side.

What’s in the kits?1K & 10K potentiometer - these pots have 0.1" spacing and fit very nicely into a breadboard without modification

What’s in the kits?2 small pushbuttons - Snap into the breadboard for button inputs

What’s in the kits?5 bright red diffused LEDs (250mcd) - indicators, blinkies, bright enough to see in the day, but diffused so that they are visible from all angles.

What’s in the kits?Red, green and blue ultra-bright LED - Can be used on their own, or color-mixed to make nearly any color in the rainbow!

What’s in the kits?5 100 ohm resistors - They can be used to protect pin outputs when starting out5 1K resistors - Good for use as LED limiting resistors5 10K resistors - Great for pullups & pulldowns

A few more concepts before building:

• Ohm’s Law!– Georg Simon Ohm was kind of the Originial

Gangster of circuit construction– He developed the simple relationship

Or current = voltage / resistance

Why is this important?

• Today we will be using LEDs or Light Emitting Diodes .• LEDs are essentially switches that emit light.• When hooked up correctly to a power source, the

current will flow through the switch in the right direction and turn it on.

• BUT, LEDs are often delicate! With too much current the LED will blow and become unusable.

• SOLUTION: We use a resistor to buffer the current through the LED.

Which resistor?

• Using Ohm’s we can determine exactly which resistor is best but it is always best to be safe than sorry.– The higher the resistance the dimmer the LED will

• We will be using the 1K resistors.– …and which one is that?

Resistor Color Coding

Resistor Color Coding

100ohm

100k ohms

Pull up/pull down resistors• Pull up/pull down is a way of setting up buttons so that they are reliable.

• When we use buttons today we will add a pull down resistor. This resistor ensures that the button registers as a ‘0’ or off whenever it is not being pushed.

• This is the function of a pull down resistor—it makes sure inputs are what we expect them to be.

Time to build!

Picture of build schematic

Program 1

This program introduces everybody to the general setup of a typical sketch

Program 2

Program 3