This document provides an introduction to microcontroller basics and working with Arduino. It covers: 1. Downloading and setting up the Arduino IDE software. 2. An overview of the Arduino Uno board's features and the basic structure of an Arduino code with setup() and loop() functions. 3. Examples of common Arduino functions for digital and analog input/output, interrupts, and PWM. 4. Two simple example codes - one using a push button and digital input, the other using a potentiometer and analog input to control an LED brightness.

1. Microcontroller basics
Starting with Arduino

2. Exercise 1
•Working with Arduino IDE
•Basic electric components
•Your first program
•Digital input and output
•Analog input and output
•Interrupts

3. Arduino IDE
• Download from:
http://arduino.cc/en/Main/Software

4. About Arduino Uno
Reset button 14 Digital I/O pins (6 PWM)
6 Analog Input pins
3.3 V and 5 V outputs
USB port
12 V input

5. Setting up Arduino IDE

6. Structure of an Arduino code
1. Define Variables
2. Setting up
functions
3. Eternal loop
void setup()
{}
void loop()
{}
Setup function is run once, when the
microcontroller boots up or resets.
After setup function the processor moves to
run code inside the loop function. Code inside
loop function will be run over and over until
the microcontroller is shut down.
int pin = 1;
Before going to the setup function constant
variables should be defined
• It’s required to have both setup() and loop()
functions in the code

7. Arduino C – Basic functions
pinMode(var1, var2) pinMode functions sets the mode of given pin. Var1 is the
number of the pin and var2 is the mode (INPUT,
INPUT_PULLUP, OUTPUT)
digitalWrite changes the status of the pin. Var1 is the
number of the pin and var2 is the status (LOW, HIGH).
digitalWrite(var1, var2)
IMPORTANT TO NOTICE:
•Depending whether the pin is set as an OUTPUT or INPUT the actual effect of
digitalWrite() is different
digitalRead(var1) digitalRead returns the current status (LOW, HIGH) of the
pin. Var1 is the number of the pin.

8. Arduino C – Basic functions
analogRead(var1) AnalogRead returns a 10-bit (by default) value equal to
the voltage of the pin relative to the analog reference
voltage.
AnalogWrite sets a pin (var1) to a voltage relative to
the analog reference voltage equal to an 8-bit (by
default) value.
analogWrite(var1, var2)
analogReadResolution(var1)/
analogWriteResolution(var1)
map(var1,var2,var3,var4,var5)
Changes the resolution of the corresponding function
to var1.
Maps the value of var1 linearly form the range var2,
var3 to the range of var4, var5. Works with negative
numbers as well.

9. Arduino C – Basic functions
attachInterrupt(var1,var2,var3) Attaches an interrupt to a pin. Var1 is determined
by digitalPinToInterrupt(pin). Var2 is the function
to be ran. Var3 is the trigger mode of the interrupt.
Detaches an interrupt. Var1 is again determined by
digitalPinToInterrupt(pin).
detachInterrupt(var1)
Disables interrupts. Used when you are running
time sensitive code for example
noInterrupts()
Enables interrupts disabled by noInterrupts().
interrupts()

10. Writing your first program
int ledPin = 13; //Variable to store the pin number
void setup()
{
pinMode(ledPin, OUTPUT); //set ledPin as output
}
void loop()
{
digitalWrite(ledPin, HIGH); //LED ON
delay(1000); //Wait 1000ms (=0,1s)
digitalWrite(ledPin, LOW); //LED OFF
delay(1000); //Wait 1000ms (=1s)
}
Basic blinking LED

11. Uploading the program
1. Click Verify
The program is
checked
2. Click Upload
The program is
uploaded to the
Arduino mCu
board
1.
2.

12. Breadboard
Terminals with blue and red lines are called power
busses and are connected together horizontally.
Terminals in the middle are connected together
vertically. The gap in the middle separates the two
sides.

13. Basic Components
Resistor
Capacitor
LED
Push button
Inductor
Transistor
Integrated circuit (IC)
Passive components Active components

14. Example 1 – Push Button
Reading digital input

15. Example 1 - Polling
byte ledPin = 13;
byte buttonPin = 2;
void setup()
{
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, LOW); //set ledPin off as default
pinMode(buttonPin, INPUT); //set buttonPin as input
digitalWrite(buttonPin, HIGH); //set the default state of the pin to HIGH (+5V)
}
void loop()
{
if(digitalRead(buttonPin) == LOW)
{
digitalWrite(ledPin, HIGH); //LED ON
}
else
{
digitalWrite(ledPin, LOW); //LED OFF
}
}
Reading digital input (Using push button)

16. Example 1 - Interrupt
byte ledPin = 13;
byte buttonPin = 2;
bool ledState = 0;
void switchLED()
{
ledState = !ledState;
digitalWrite(ledPin, ledState);
}
void setup()
{
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, LOW); //set ledPin off as default
pinMode(buttonPin, INPUT_PULLUP); //turn on the internal pullup
attachInterrupt(digitalPinToInterrupt(buttonPin), switchLED, CHANGE); //creates
the interrupt
}
void loop()
{
//waiting for interrupt
}
Using an interrupt for the same job

17. • Microcontrollers typically operate on low
voltages (0-5V). Even so you must be careful
when connecting devices.
• Know the electrical limits of the
microcontroller: Uno can handle max
5V/40mA per I/O pin
• Always double check the wiring! If you see
smoke it’s already too late!

18. P=U*I M U=R*I
• To prevent overloading a pin or a component
with excessive current you need to use a
resistor
• Example: Using an LED – Calculating the
required resistor size
• Operation voltage for LED: 5V
• Recommended current 23mA
• 𝑈 = 𝑅 ∗ 𝐼 → 𝑅 =
𝑈
𝐼
=
5𝑉
0,023𝐴
≈ 220Ω

20. PWM (Pulse Width Modulation)
• Basic terms
• Duty cycle = Pulse Width / Wave Period

21. Duty cycle
• 100 %
• 75 %
• 50 %
• 25 %
• 0 %
←Ideal Square Wave

22. PWM Applications
• Servomotor angle control
• DC motor speed control
• LED Dimming
• Audio generation
• Digitally generating analog voltages (requires
filtering)

23. PWM with Uno
• Total of 6 pins with PWM capability (~ symbol)
• PWM frequency
– Pins 5 & 6: default: 980Hz ~1kHz
(62.5kHz base with 64 as prescaler)
– Pins 3,9,10,11: default 490Hz ~0.5kHz
(31.25 kHz base with 64 as prescaler)
• Can be adjusted (30Hz-62.5kHz) with setPwmFrequency();
http://playground.arduino.cc/Code/PwmFrequency
CAUTION: Affects the delay() millis() and Servo functions

24. Example 2 – Control PWM LED
Longer pin
Using an analog input to control a PWM LED

25. Example 2 - Analog I/O
int ledPin = 3; //Variable to store the pin number
int potPin = A0; //Variable to store the pin number
void setup()
{
pinMode(ledPin, OUTPUT); //set ledPin as output
pinMode(potPin, INPUT); //set potPin as input
}
void loop()
{
int potValue = analogRead(potPin); //Read the value of the potentiometer
int ledValue = map(potValue, 0, 1023, 0, 255); //map to correct range
analogWrite(ledPin, ledValue); //Read the value of the potentiometer
delay(10); //To run the loop ~100 times a second
}
Potentiometer controlled PWM LED

26. In the next exercise
• USB communication
• Sensors