Lesson 17 – Reading an Analog Value

Setup

  1. Before you start working with any of the tutorials in this series please make sure you have completed the following tasks –
    1. Downloaded and installed the Arduino IDE.
    2. Are able to connect to the Arduino IDE from your computer
    3. Have been successful in uploading a simple (e.g. Blink LED’s) example programs (that comes with the Arduino IDE) onto your Arduino UNO board
  2. If you haven’t installed the Arduino IDE please head back to the first tutorial and make sure you’ve gone through each of the steps involved.
  3. Once you’ve sorted all of the above you are ready to move onto the next tutorial.

Tutorial

In this experiment, we will begin the learning of analog I/O interfaces. On an Arduino, there are 6 analog interfaces numbered from 0 to 5. These 6 interfaces can also be used as digital ones numbered as 14-19.  After a brief introduction, let’s begin our project. Potentiometer used here is a typical output component of analog value that is familiar to us.

Here’s the hardware you will need for the tutorials –

  1. Arduino Board x1
  2. Potentiometer *1
  3. UNO board *1
  4. Breadboard*1
  5. USB cable *1
  6. Breadboard jumper wire * 3

In this experiment, we will convert the resistance value of the potentiometer to analog ones and display it on the screen. This is an application you need to master well for our future experiments.

You will find fritzing diagrams below outlining circuit connections for both the Arduino Uno and the Arduino Mega 2560.

Open up the Arduino console once you’ve uploaded your code and here’s what you should be seeing.

The analog interface we use here is interface A0.

The program compiling is simple. An analogRead () Statement can read the value of the interface. The A/D acquisition of Arduino 328 is in 10 bits, so the value it reads is among 0 to 1023.
One difficulty in this project is to display the value on the screen, which is actually easy to learn. First, we need to set the baud rate in voidsetup (). Displaying the value is a communication between Arduino and PC, so the baud rate of the Arduino should match the the one in the PC’s software set up.

Otherwise, the display will be messy codes or no display at all. In the lower right corner of the Arduino software monitor window, there is a button for baud rate set up. The set up here needs to match the one in the program. The statement in the program is Serial.begin(); enclosed is the baud rate value, followed by statement for displaying. You can either use Serial.print() or Serial.println() statement.

Let’s have a look at the code for the tutorial.

int potpin=0;// initialize analog pin 0
int ledpin=13;// initialize digital pin 13
int val=0;// define val, assign initial value 0
void setup()
{
pinMode(ledpin,OUTPUT);// set digital pin as “output”
Serial.begin(9600);// set baud rate at 9600
}
void loop()
{
digitalWrite(ledpin,HIGH);// turn on the LED on pin 13
delay(50);// wait for 0.05 second
digitalWrite(ledpin,LOW);// turn off the LED on pin 13
delay(50);// wait for 0.05 second
val=analogRead(potpin);// read the analog value of analog pin 0, and assign it to val 
Serial.println(val);// display val’s value
}

The sample program uses the built-in LED connected to pin 13. Each time the device reads a value, the LED blinks. When you rotate the potentiometer knob, you can see the displayed value change. The reading of analog value is a very common function for most sensors output analog value. After calculation, you can get the corresponding value you need.

Happy hacking!!!


Prerequisites

This development track requires an investment a bit of hardware. See below for details –

  1. Arduino IDE –
    1. You will need to download and install the Arduino development IDE.
    2. The approach to installation, configuration, setup of the Arduino IDE is covered in our tutorials.
  2. Arduino Uno, Sensors, etc. –
    1. You will need to purchase the Super Learning Kit for Arduino from OzToyLib.
    2. The Arduino Advent kit has all the sensors you need to perform the tutorials covered in this development track.
    3. If you do not have an Arduino Uno or Arduino Mega 2560 you might want to head over to Arduino boards and pick one up now.

The Super Learning Kit for the Arduino kit has all the sensors you need to perform the tutorials covered in this development track.


About the Super Learning Kit for Arduino

The Super Learning Starter Kit for Arduino comes packed with ~35+ different electronic bits (Sensors, LEDs, switches, LCD, servo, etc.) and can be purchased with either the Keyestudio UNO R3 or the Keyestudio Mega 2560 board. The Keyestudio Arduino boards can be used to interface with the different electronic bits i.e. sensors, LED’s, switches, servos, etc. included in the starter kit. The starter kit for the Keyestudio Uno R3 offers a great opportunity to explore the world of electronics using the Arduino Development Platform. Interact with the real world through the various sensors, create innovative projects, learn how to program the micro:bit to read data from the sensors and perform certain actions. The starter kit for the Arduino is a great way to dive into the awesome world of electronics and get started with your own STEM (Science, Technology, Engineering, Math) learning journey.

The Arduino advanced study kit walks you through the basics of using the Arduino in a hands-on way. You’ll learn the fundamentals of electronics and working on the Arduino through building several creative projects. The kit includes a selection of the most common and useful electronic components with a book of 32 projects. Starting the basics of electronics, to more complex projects, the kit will get you interacting with the physical world using sensor and actuators. Along with the kit you get access to detailed tutorials and wiring diagrams.

You can purchase the Super Learning Kit for Arduino from OzToyLib.


About the Arduino UNO

The Arduino UNO is the most used and documented board of the whole Arduino family and very easy to setup, play with. The Arduino UNO is a microcontroller board based on the ATmega328 . The Arduino UNO has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz ceramic resonator, a USB connection, a power jack, an ICSP header, and a reset button. Here’s a listing of the some of the features of the Arduino UNO –

  1. Microcontroller: ATmega328
  2. Operating Voltage: 5V
  3. Input Voltage (recommended): 7-12V
  4. Input Voltage (limits): 6-20V
  5. Digital I/O Pins: 14 (of which 6 provide PWM output)
  6. Analog Input Pins: 6
  7. DC Current per I/O Pin: 40 mA
  8. DC Current for 3.3V Pin: 50 mA
  9. Flash Memory: 32 KB of which 0.5 KB used by bootloader
  10. SRAM: 2 KB (ATmega328)
  11. EEPROM: 1 KB (ATmega328)
  12. Clock Speed: 16 MHz

Arduino is an open-source, prototyping platform and its simplicity makes it ideal for hobbyists to use as well as professionals. The Arduino UNO contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Arduino UNO differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega8U2 microcontroller chip programmed as a USB-to-serial converter. “Uno” means one in Italian and is named to mark the upcoming release of Arduino 1.0. The Arduino Uno and version 1.0 will be the reference versions of Arduno, moving forward. The Uno is the latest in a series of USB Arduino boards, and the reference model for the Arduino platform.

You can read more about the Arduino here – www.arduino.cc.

Questions