Introduction to Arduino Programming

Arduino Programming(C) 2014 James Lewis

james@baldengineer.com

1

Arduino Langauge

2

Machine Language (Binary Code)

Assembly (Readable Code)

C / C++ (Readable Code)

C++ Libs

C++ Libs

C++ Libs“Arduino”

Arduino Langauge

3

Machine Language (Binary Code)

Assembly (Readable Code)

C / C++ (Readable Code)

C++ Libs

C++ Libs

C++ Libs“Arduino”

Hello World (Blink)

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Hello World (Blink)

5

Variable

Hello World (Blink)

6

Comments

Hello World (Blink)

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Comments

Good Comment: // Blue LED for Activity Indicator

Bad Comment: // Pin 13

Hello World (Blink)

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Functions

Hello World (Blink)

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Functions

Hello World (Blink)

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Instruction

Hello World (Blink)

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Instruction

Hello World (Blink)

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Function Call

Hello World (Blink)

13A

rguments

Hello World (Blink)

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IDE Tools Menu

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IDE Tools Menu

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IDE Tools Menu

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IDE Tools Menu

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Arduino IDE

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Type Stuff Here

Compiler Output

Arduino IDE

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Type Stuff Here

Compiler Output

Serial Monitor

Arduino IDE

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Type Stuff Here

Compiler Output

Serial MonitorVerify & Upload

Arduino IDE

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Type Stuff Here

Compiler Output

Serial MonitorVerify & Upload

Board & Serial Port

Blink Exercise

• Load the Blink Example and program it to your board

• Change the values of delay() to see how it affects the behavior

23Check the correct board and serial port are selected in the tools menu!

Hello WorldSerial Example

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Serial objects

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Serial objects

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Enables Serial

Baud

Rate

Serial objects

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Variables Strings

Control Characters

Print and Println

Serial objects

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Variables Strings

Control Characters

Print and Println

NOTE: Strings and Variables Can’t be used on the same line

Hello World (Serial)

• Load up the serial code to the right

• Exercise:

• Change the 2000 in delay into a variable.

• Print value of variable on same line as “Hello World”

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Variables

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How Much Memory is in your Arduino?

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Variable Types

32

Bits Unsigned Range Signed Range

byte 8 0 to 255 N/A

char 8 0 to 255 ‘A’..’b’..’X’ N/A

int 16 0 to 65535 -32,767 to 32,766

long 32 0 to 4,294,967,295-2,147,483,648 to

2,147,483,647

float 32 ±3.4028235E+38 n/a

double 32 n/a n/a

Variable Do and Don’t• DO Use Descriptive Names

• “BlueLED”, “ActivityIndicator”

• DON’T Use Bad Names

• “Integer”, “Pin13”

• DO Stick to a naming convention

• Variables are Case Sensitive!

• DON’T use same name for Local and Global Variables

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Variable Scope

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Variable Scope

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Global

Variable Scope

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Global

Local to loop()

Variable Don’t!

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Variable Don’t!

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Variable Don’t!

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analogReadings[]

arrays

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0 1 2 3 4 5

analogReadings[]

arrays

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0 1 2 3 4 5

Size

Elements

analogReadings[]

arrays

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0 1 2 3 4 5

Size

Elements

arrays are 0-index based.

So last element is always “1 less”

than the size!

Pin Functions

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pinMode()

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Analog(A0..A5)

Digital(0..13)

INPUT Digital Input, Pull-Up Off

Digital Input, Pull-Up Off

INPUT_PULLUP Digital Input, Pull-Up On

Digital Input, Pull-Up On

OUTPUT Digital Output Digital Output

Analog Pins can be used as Digital Pins pinMode(INPUT, Ax) isn’t necessary for analogRead()

digitalRead() & digitalWrite()

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Pull-Up Resistor

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INPUTs almost always need a Pull-Up or Pull-Down pinMode(INPUT_PULLUP) Turns on the Internal Pull-Up Resistor

http://www.baldengineer.com/tutorials/arduino-pull-ups/

I/O Exercise

• Objective: Understand Inputs and Outputs

• Exercise: “Fix” the random LED

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analogRead()

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Analog Signal

Convert Digital Value

10-bits, stored as 8-bits

Values 0 to 1023

Voltage

0v to 5v

5 volts

1023 Steps= 4.887mV per Step

Calling analogRead() on an Analog Pin, automatically converts to Input

analogWrite()

49

analogWrite() isn’t Analog (Except on the Due) Uno Pins: 3, 5, 6, 9, 10, 11

Actual AnalogPulse Width Modulation (PWM)

Analog Exercise

• Connect Pin 6 to Analog 0 Run this code

• Then, disconnect from Pin 6 While Running the Code

50Remember to open the Serial Monitor!

Analog Exercise

• Connect Pin 6 to Analog 0 Run this code

• Then, disconnect from Pin 6 While Running the Code

51Remember to open the Serial Monitor! A0, A1, A2..A5 are integers!

functions()

52

Functions Getting Data Back

Functions Getting Data Back

Tip: The Arduino IDE, doesn’t require “prototyping”

Functions Getting Data Back

Return Type

Argum

ents

“Ret

urn”

Function Nam

e

Functions Returning Nothing

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Return Type

If the function doesn’t return anything, declare it as void

Function Exercise

• “Re-Write” the built-in Blink Example to use a Function

• Exercise: add a “argument” to adjust the delay time

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Control Structures

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if-statements

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if-statements

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if-statements

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if-statements

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control operators

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== Equal to

>>=

Greater than (or equal)

<<=

Less Than (or equal)

!= Not Equal to

|| OR

&& AND

| Bitwise OR

& Bitwise AND

#1 if-statement mistake

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#1 if-statement mistake

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= != ==

for() loop example

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for() loop

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for() loop

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Control Variable

for() loop

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Control Variable

Condition

for() loop

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Control Variable

Condition

Increment

Array and For Exercise

• Use an Array and two for-loops to read analog inputs, then display then

• Notice the difference in brackets between the two loops

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while() loop

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while() loop

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Condition

while() loop

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Condition

Loop conditions are same as “if conditions”

while() and Serial

• This program echoes whatever is on the serial buffer back out

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