Arduino Basics and PWM Pins

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Questions and Answers

Which pins on the Arduino UNO can be used for PWM?

7, 8, 12, 13, 14

1, 2, 3, 4, 5

3, 5, 6, 9, 10, 11 (correct)

0, 1, 2, 4, 13

What is the primary purpose of the analogWrite() function?

To set a digital output pin to HIGH or LOW

To write a PWM signal to a pin (correct)

To read the voltage of a pin

To configure a pin mode

What does the digitalRead() function return when a pin is configured as INPUT and the pin state is LOW?

0V and pull-up disabled (correct)

20K pull-up resistor enabled

Analog voltage value

How does the millis() function differ from the delay() function?

millis() does not pause program execution Signup and view all the answers

What is the effect of using the digitalWrite() function on a pin configured as OUTPUT?

Set the voltage to HIGH or LOW Signup and view all the answers

What happens when the wavelength of the PWM signal is too slow for human perception?

The LED appears to dim gradually Signup and view all the answers

What is the purpose of using the delay() function?

To pause the program for a specified duration Signup and view all the answers

What does the function micros() return?

The number of microseconds since the program started Signup and view all the answers

What does the pinMode() function in an Arduino sketch do?

Defines a pin as an input or output Signup and view all the answers

What is the purpose of the delay() function in Arduino?

To introduce a pause measured in milliseconds Signup and view all the answers

How does PWM (Pulse Width Modulation) create a fake analogue signal?

By toggling a pin high and low over time Signup and view all the answers

What is the primary function of the micros() command?

To measure elapsed microseconds since the program started Signup and view all the answers

Which function would you use to send a high digital value to a pin in an Arduino sketch?

digitalWrite() Signup and view all the answers

Which of the following correctly uses the syntax for the analogWrite() function?

analogWrite(pin, value) Signup and view all the answers

What is the primary characteristic of the setup() function in an Arduino sketch?

It initializes settings once at the start Signup and view all the answers

What is the maximum value that can be set for the duty cycle in the analogWrite() function?

255 Signup and view all the answers

When using the analogWrite() function, what range of values can be sent to a pin?

0 to 255 Signup and view all the answers

What feature allows a sketch to gradually light up an LED?

Fade In technique Signup and view all the answers

What does the digitalRead() function return in an Arduino sketch?

A binary value (high/low) Signup and view all the answers

Which pins on most Arduino boards are capable of using the analogWrite() function?

2, 3, 5, 6, 9, 10, 11 Signup and view all the answers

In a schematic, what do the little arrows in the LED symbol indicate?

Direction of current flow Signup and view all the answers

Study Notes

Arduino Uno PWM Pins

Arduino Uno can only do PWM on pins 3, 5, 6, 9, 10 and 11
PWM is effective for dimming LEDs when pulse frequency is faster than the eye can perceive

Arduino Sketch Structure

Arduino programs are called sketches
Two main functions in a sketch:
- setup(): runs once at program start, used for initialization
- loop(): runs continuously until the board is powered off

Arduino Functions

pinMode(): configures a pin as an input or output
- Parameters:
  - pin: pin number
  - mode: INPUT, OUTPUT, or INPUT_PULLUP
digitalWrite(): writes a HIGH or LOW value to a digital pin
- Parameters:
  - pin: pin number
  - value: HIGH or LOW
digitalRead(): reads a HIGH or LOW value from a digital pin
- Parameters:
  - pin: pin number
delay(): pauses program execution for a specified amount of time in milliseconds
- Parameters:
  - ms: number of milliseconds to pause
millis(): returns the number of milliseconds since the program started
- Parameters: None
micros(): returns the number of microseconds since the program started
- Parameters: None
analogWrite(): writes an analog value (PWM) to a pin
- Parameters:
  - pin: pin to write to
  - value: duty cycle from 0 (off) to 255 (on)
- Pins 5 and 6 on Uno boards have a frequency of approximately 980 Hz
- Pins 3 and 11 on Leonardo boards have a frequency of approximately 980 Hz
- Most other pins run at approximately 490 Hz
Serial: used for communication between the Arduino board and a computer or other devices
- Communicates on digital pins 0 (RX) and 1 (TX)
- Communicates with the computer via USB
Serial.begin(): initializes the serial communication

Breadboard Guide

Each electronic component has a simplified drawing (schematic symbol)
The LED symbol has an arrow indicating the direction of current flow
External LEDs can be connected to a breadboard
The Arduino reference page offers more information on specific components

Basic Electrical Knowledge

Resistors are used to limit current flow
LEDs require a resistor to prevent damage

PWM (Pulse Width Modulation)

PWM creates a fake analog signal by toggling a pin high and low
The overall time spent high affects the average voltage of the signal

Example Sketches

Fade In: gradually lights up an LED
Fade Out: gradually fades out the light of an LED
Fade In and Out: mimics a heartbeat by fading the LED in and out

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Description

This quiz covers the fundamental concepts of Arduino programming, including the PWM (Pulse Width Modulation) pins specific to the Arduino Uno and the structure of an Arduino sketch. You'll learn about essential functions like pinMode, digitalWrite, and delay that are crucial for controlling input and output on the board.