This document provides an overview of digital I/O with Arduino. It discusses digital signals having two possible values like 0V or 5V. Digital inputs can detect if something is true or false like a door being open. Digital inputs have two states: off and on. Sources of digital input include push buttons and switches. Digital outputs can turn things on or off like controlling an LED. Examples of digital outputs are LEDs, buzzers, and LED matrices. The Arduino digital I/O pins and functions like pinMode(), digitalWrite(), and digitalRead() are also covered. Projects demonstrated include a blinking LED, traffic light, and blinking LED controlled by a switch.

1. ARDUINO COURSE
Collected By : MohamedZain Allam

2. Lecture 3
Digital I/O

3. Digital signal:
Digital signals must have a finite set of possible values.
The number of values in the set can be anywhere between two and a-very-large-number-
that’s-not-infinity.
Most commonly digital signals will be one of two values – like either 0V or 5V.
Timing graphs of these signals look like square waves.

4. Digital Inputs:
-When you’re trying to sense activity in the physical world using a microcontroller
-the simplest activities you can sense are those in which you only need to know one thing
about the physical world: Whether something is true or false.
-Is the viewer in the room or out? Are they touching the table or not? Is the door open or
closed?
-you can determine what you need to know using a digital input, or switch.

5. -Digital or binary inputs to microcontrollers have two states: off and on.
-If voltage is flowing, the circuit is on. If it’s not flowing, the circuit is off.
-To make a digital circuit, you need a circuit, and a movable conductor which can either
complete the circuit, or not.

6. Sources of digital input:
-Push Button

8. -switch

9. -Digital Sensors

10. Digital output:
-With a digital output you can either turn something off or on.
-The diagram below is the schematic diagram for digital output controlling an LED:

11. Examples of digital output
-LED

14. How to calculate the resistor value ?
-LED current equal from 10 to 20 mA (14mA)
-LED voltage equal 2v
-Arduino output current = 40 mA
-Arduino output Voltage = 5V
- Ohm’s law ( V = I * R ).
-R=V/I R=(5-2)/(14*10^-3) = 214 ohm
- From the values of the resistors in the stores we can use (220,330 ohm)
-the power of the resistor P=I^2 * R P=(14 *10^-3)^2 * 330 = 0.064 W

15. -LED Matrix:

16. -Buzzer

17. Arduino Digital i/o pins

18. Arduino C
-pinMode(A , INPUT or OUTPUT );
-digitalWrite(A , HIGH or LOW );
-digitalRead(B);
-delay(C);
A : the num. of digital output pin.
B : the num. of digital input pin.
C : the time in millisecond , when second = 1000 m.sec

19. project
Blinking LED:
-hardware:
Arduino Uno – Arduino USB cable – LED – Resistor 330ohm – wires male to male
-software:
Arduino IDE – proteus simulation program

20. Hardware Review:
-Test Board :

21. -Wires:
Female to FemaleMale to Male Male to Female

22. Resistors:

23. project
-Traffic Light:
change the color each 0.5 sec

24. project
-Blinking LED with switch:

25. Task