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Python Init Function Example, Syntax & Best Practices

In this article, we will take a look at the Python Init Function using an example. At first, we learn about it’s syntax and how we can use it. But once we are comfortable with it, we will then learn the best practices to use when we want to call it!

So, does this plan sound good? Yes? Then let’s do it! 😉

Python Init Function Example and its syntax
Python Init Function Example and its syntax explained in 5 minutes

What Is The Syntax Of Python Init Function?

So first, let us start with how the syntax of a Python Init function looks like. Now, for us to know about it, we will have to take a look at the Python’s official document. From this, we now get to know that the init function is a method of a class and it looks like:

def __init__(self)

From the above code, we can see that the init function takes at least one argument. This is called as ‘self‘ and it has got a special meaning to it. But before we learn about it, let us first know how Python’s Class works.

You see, in Python a Class can have many methods in it. But it will have one method in it for sure. It is called the init() method. Now this method will be present in a Python Class even if you have not declared it yourself!

So, in other words, init() is a function that you will always find in any Class of Python. If you declared it yourself, it is an explicit init() function. But if you did not, it will be an implicit init() function!

Alright, so we now that an init() function is always present in any Python Class, what does it do? We will answer this question next!

Why do we need an init() function in Python?

So to answer this, we need you to have some knowledge about Object Oriented Programming (OOP). So if you are not so familiar with it, please go and learn about constructors in OOP. But for now, I will assume that you do know about OOP.

So as you know in OOP, we have a constructor method in every Class. So whenever we create an object using a Class, its constructor method will get called. Right?

In the same way, in Python the init function acts as a constructor. So it will get called whenever we create a Python’s Class object.

So this is why I said that the init() function is always present in a Python Class. So, the syntax of the init() that you saw above is how it looks like when it is implicit.

What does the self parameter do?

In order to answer this, let us take a look at the syntax once again

class Test:
    def __init__(self)

Here, we are looking at the code of an example Python class called Test. So here we can see that the init function has one argument called self.

Now, in order to for us to understand what this self argument does, let us first create an object of the Test class type.

t = Test()

So in the above code, we created a new object instance of the Test class. Now, as soon as this code runs, the init() function of the Test class will get called. But what is getting passed as the self argument here the variable t itself.

So, we now see that the self argument of the init() function points to the instance of the object itself!

Are you clear until now? Good! Then let us now look into an example of Python Init() function.

Python Init Function Example

So, let us take a look at this Python Init function example code

class Point:
    def __init__(self, x, y):
        _x = x
        _y = y

p = Point(1,2)

From the above code, we can see that we now have a new Class called Point. We also have an init() function that we have defined explicitly. This init() function takes in three arguments self, x & y.

Is it all clear? Good!

So we can quickly see the advantage of using init() function here. With the help of this function, we are able to set the initial values of x & y variables!

So when we created an instance of Point class using the code:

p = Point(1,2)

we were able to set the p object’s x & y values to 1 & 2 right away!

So, if things are clear until this point, we will then move on to the last part of this article.

Best Practices With Python Init Function

So here is a list of best practices you should follow when writing an init function:

  • Always use Init() function to initialize values to object parameters
  • Reduce the number of parameters passed to the init() if possible. Do not over use it.
  • Keep the init() function simple. Do not abuse it!

Conclusion

So that is about it! That is all you need to know about Python init() function. We have discussed everything there is to know about Python’s init() function with an example. We also went through the best practice we should follow when making use of it.

So with this, I will end this article here. If you still have any more questions, please ask it in the comment section below!

Know the difference between an expression Vs statement in Python

So until next time, have a nice day! 🙂

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Buy Arduino Nano Online At A Low Price

In this article, we will learn how you can buy an Arduino Nano online. We will learn how to buy it online in India at a low price. But before we do that, let us first learn what an Arduino Nano is in the first place. So are you ready to dive in? Then let us go!

What Is An Arduino Nano Board?

If you are still a beginner in the embedded world, chances are you may have not heard about Arduino Nano until now. So what is it?

Well, the Arduino Nano is a small computer board that one can buy to learn more about computers. It is a computer on a single PCB board that contains all the circuitry needed to run the software code on it.

Oh wait a second here! So we are learning that it is a single board computer, right? Cool! But then you may be wondering how does this Arduino Nano look like?

I am glad you asked this question! Here is a picture of an Arduino Nano board I will share with you for your pleasure. Take a look at it.

Arduino Nano Board Available To Buy Online
Arduino Nano Board You Can Buy Online

Woah! That is one weird looking single board computer out there! But what are all those pins coming out of it?! Looks scary isn’t it?

But don’t worry. Even though the Arduino Nano board looks like that, it is actually easy to use. There are many tutorials we have that will teach how to use it. So learning how to work with it will never be a problem at all.

So with this introduction to Arduino Nano, it is time for us to move on to know how we can buy it online.

How To Buy Arduino Nano Online?

There are many sellers who are selling the Arduino Nano hardware board. They are selling these Arduino Nano boards in online stores as well as in the offline stores. However, when you try to buy the Arduino Nano board, you will realize that the price differs a lot from one seller to another!

Now this is happening because there they are all not original Arduino boards. You see, the thing is Arduino boards are all launched as open source hardware boards. So, their circuit as well as their board designs are all available for free for anyone to use.

So, what happened because of this is that there are many Arduino Nano clones as well. Since these Arduino clones are coming from China, they will be of cheaper cost.

So in that case, who is the original manufacturer of Arduino Nano?

Arduino is the company that designs and manufactures the original Arduino boards. But as this company is from Italy, the products it makes are costlier than their clones.

So now this begs us with our next question which is:

Who manufactures the Arduino clones?

Most of the Arduino clones manufacturers are from China. So since the manufacturing cost of these boards are cheaper in China as compared to Italy, the clones are always cheaper.

So here is the real reason then! This clearly tells us why we see so much difference in the price for the same Arduino Nano boards across different online websites!

So depending on how much you can spend, decide which Arduino Nano board you want to go for.

What is the difference between an original Arduino Nano Vs a Nano clone?

Now as I told earlier, both the original and the cloned Nano boards use the same circuit design. So nothing is different over here. But there is one difference between the two. And this difference is in terms of the quality of components used.

So if you want a higher quality board, you pay more and go for original Nano module. But on the other hand, if you want to spend less, just go for a Nano clone. It really doesn’t matter at all. Trust me!

What Is The Price Of Arduino Nano Online In India?

If you are from India, you can buy the original Arduino Nano online at a low price of Rs.1449. But if you are OK to buy a cheap Arduino Nano clone, you can buy it at a low cost of Rs.200!

What Is The Price Of Arduino Nano Online In The US?

In the US, you can buy an original Arduino Nano at a cost of $22.00. But on the other hand, a cloned Arduino Nano will only cost you around $9! It’s as cheap as that!

What Is The Online Price Of Arduino Nano In The UK?

But if you are in the UK, you can buy the Nano board at just GBP20!

Have you looked at the new Arduino Portenta?

Conclusion

So there you have it. We just looked into the price of an Arduino Nano in 3 different regions. I also explained to you why its price changes so much when you want to buy it online. It is because of the clones that has reduced the price of these boards.

I hope you have got what you were looking for in this article. If you still have any more questions on it, ask me right away and I will answer you.

I hope you will have fun working with them. These are the best things you can work on to gain good knowledge. It is also one the best hobby that will keep you busy for some time! So enjoy with your new toys! Until next time, ciao! 🙂

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Arduino Portenta Technical Specification & Price

In this article, we will take a look at the technical specification of Arduino Portenta. But along with this, we will also learn about its price during its release date.

Just today, Arduino launched its new product called “Arduino Portenta” at CES 2020 show in Las Vegas. So far from what I have learnt, it is an IoT device. Which means that you can use it to connect things in your house to the internet!

But not just that! The company is also claiming that we can use Arduino Portenta even in industrial applications.

Ok, all this is fine. But why do we even need this device in the first place? To answer this question, we first need to discuss the technical details of Arduino Portenta. So let us first do that!

Arduino Portenta H7 Technical Specification

Arduino Portenta H7 Processor

The Arduino Portenta H7 is driven by the ST Microelectronics’ STM32H747XI low power processor. This processor is made up of dual ARM Cortex cores.

The first ARM core present in it is a Cortex-M7 running at 480 MHz. On the other hand, the second ARM core is made up of Cortex-M4 and running at 240 MHz. So with these two cores together, this ARM processor is able to run Arduino code, Python and Javascript code as well!

Now this is very interesting! Since it can run Javascript, many of the web developers will be able to work on it!

What OS does the Portenta H7 run?

We got to know that Portenta H7 is running on Arm’s Mbed OS! This is amazing! Being able to run an embedded operating system will mean we can make use of all the resources efficiently!

What type of connectivity does the Portenta H7 have?

Arduino mentioned that they support all the standard connectivity we can expect. So that means it has support for Bluetooth Low Energy, WiFi and LTE as well!

UPDATE On The Radio Module Of Arduino Portenta

We just got to know that the Arduino Portenta features a Murata 1DX dual WiFi 802.11 chipset. This chipset also has support for Bluetooth 5.1 BR/EDR/LE!

Arduino Portenta H7 with Technical Specification and release date
Arduino Portenta H7 IoT Module

What GPU Type Can We Find In Arduino Portenta H7?

The technical specification of the Arduino Portenta H7 mentions that it features a Chrom-ART graphical hardware accelerator.

What does the technical specification say about Timers in Arduino Portenta H7?

Alright guys. We know that in order for us to work with any time sensitive operation we need support of timers. So how does we score here? Well luckily on the timer front, the board has a total of 22 watchdogs and general purpose timers in it. So we have all the room to take its advantages!

But what about the UART ports in Portenta H7?

Ofcourse even though we have moved towards wireless connectivity, we still need good old UART ports for many reasons. So how do we fare on this front? Well the Arduino Portenta H7 strikes back once again! It is exposing a total of 4 UART Ports. And among these 4 ports, two of the UART ports have support for flow control.

How many connectors are exposed on the Arduino Portenta H7 board?

The Arduino Portenta H7 board exposes a total of 160 pin connectors. These connectors are grouped into two 80 pin sets and will expose all the peripherals present in the Portenta H7 board.

What type of USB does Arduino Portenta H7 support?

On the USB front, Arduino Portenta H7 exposes a USB Type C connector. This USB-C connector has support for host/device, displayPort out. It can operate at high speed or full speed USB protocol configuration. The Portenta H7 USB-C also supports Power delivery.

What is the operating temperature range of Arduino Portenta H7?

Arduino Portenta H7 can operate at a temperature range lying between -40 °C to +85 °C when running without the wireless module. But with the wireless module, Portenta H7 can operate in the temperature zone of  -10 °C to +55 °C.

What is the operating voltage of Arduino Portenta H7 acccording to its technical specification?

Arduino Portenta H7 works at 3.3 Volts.

What type of battery does Portenta H7 support?

The Arduino Portenta H7 runs on a Li-Po battery. This battery has an operating voltage of 3.7 Volts and a discharge rating of 7000mAh.

Does Arduino Portenta H7 support an SD Card?

Yes it does! The Portenta board has an SD card interface support. However, this SD Card interface is available only through an expansion port. So that is a bit of a bummer! 🙁

But now that we know the Arduino Portenta H7 technical specification, when will it Release?

I know I know. No matter how good the device is, we cannot take advantage of it until it gets in our hands, right? So we can understand when you are eager to know when this module is going to be released.

So from what we got to know, Arduino Portenta H7 is already made availale for beta testers. But it is going to become available for everyone by February 2020! Guys, that means we are just a month away from getting hold of it in our hands!

Now that we went through it’s technical specification, What will be the price of Arduino Portenta H7?

Cool! So now that we know we can get hold of Portenta by next month, our next question is obviously this.

How much it is going to cost?

Unfortunately at this point in time, I could not find an answer (Look for update at the end of this article for pricing information) for this. So I will continue to look out for this information. Once I find it, I will revisit this article and update it with the latest price. But until then, I can only leave you guessing about it.

But on the other hand, if you have any idea about it, let me know in the comments below. And not just that, if you have any other information about Portenta H7 in general that I have missed here, do let me know. In this way, I can update this article in the future for others to benefit out of it.

So there you have it. I have shared all the information I had about Arduino Portenta H7 here. While for me this device is something I am eagerly looking forward to, I wish it had a better name. Somehow for me, the name Portenta H7 is becoming difficult to remember. But may be it is just me I guess.

So any case, I will end this article at this point. So see you guys again in the next article. Until then, take care! 🙂

Latest Update On Arduino Portenta Price

We just got to know that Arduino Portenta will cost USD 99.90 + Tax.

So the cost of Arduino Portenta in the US will be $100 + taxes

The cost of Arduino Portenta in the UK will be around GBP 77 + taxes

The cost of Arduino Portenta in the European countries will be around 90 + taxes Euros

And finally the cost of Arduino Portenta in India will be around Rs.72000 + taxes

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What Are Python Reserved Keywords?

Python reserved keywords are those words in Python programming language that have a specific meaning in a program. These keywords have specific actionable functionalities defined to it in Python. We are not allowed to re-use these reserved keywords. It is also not possible to override the keywords in Python.

Why Do We Have Python Reserved Keywords?

A programming language is defined by a set of keywords that have specific functionalities attach to it. Python programming language is no different from this. There are a set of keywords defined in Python language that performs specific tasks within the program where they are used.

Python Logo For Reserved Keywords In Python

For example, print is a keyword in Python which instructs the Python interpreter (i.e. the Python environment where Python programs run) to print a string to the output terminal. So a Python program line like:

print('Hello, World!')

will print the string:

Hello, World!

to the computer output screen that its user can see. We as a programmer are never allowed to use same keyword “print” for any other purposes like variable name or function name. Thus, we say that it is a Python reserved keyword.

Similarly, the keyword input is used to receive input from the user of a Python program. So a line in the program like:

user_name = input('Enter your name')

will display the string:

Enter your name

on the user screen and wait until the user enters his name. Once he enters the name and hits the “Enter” key, the name gets stored in the variable “user_name“.

So as you can see here, each of these reserved keywords such as print, input etc. each have a very specific functionality attached to it in Python language. We cannot use these same keywords as a variable name or function names. Trying to do so will result in the interpreter throwing error at us!

So now that we understand about reserved keywords in Python, what can we do about them?

For one, we need to know about all the Python reserved keywords to avoid using them in other ways in our program. But in addition to this, knowing about these reserved keywords and their intended functionalities will also help us write useful programs.

Using Reserved Keywords In Python Programs

Python programs are nothing but a bunch of reserved keywords used upon a set of variables to perform certain operations. So we use these set of keywords to write our programs. For example, if we take a look at the below program:

user_name = input('Enter your name')
print('Hello, ' + user_name + '!')

This program simply prompts for an user to enter his name. When he does so, it will just wish Hello to him by addressing his name. So when I run this program, the output I get is something akin to this:

'Enter your name'
> Amar
> Hello, Amar!

Conclusion

So in short, we can say that reserved keywords are a set of words in Python that have pre-defined meaning and functionalities associated with them. We make use of these keywords to write our program and we are not allowed to re-use the same words in our variables or function names. In other words, we are not allowed to alter their pre-defined meaning.

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Python Program To Add Two Numbers

In this article, we will look at how to write a Python program to add two numbers. This is a very simple Python program that is suitable for even a beginner in Python programming to work on it for getting hands on practice with Python.

In order to add two numbers in Python program, we need to first break down the problem into the following steps:

Breakdown of the problem of Adding two numbers

  1. Receive the first input number from the user and store it in a Python variable.
  2. Receive the second input number from the user and store it in another Python variable.
  3. Add the two numbers by adding the two Python variables using a Python statement (Learn about Python statement here)
  4. Store the final result in another Python variable called “result”
  5. Print the value of the “result” variable.

In the above breakdown of the problem, you will notice that the Python program we will be written in such a way that the two numbers that need to be added will not be hard coded directly into the program itself but instead is written in a generic way such that we prompt the user to enter these two input values every time the Python program to add two numbers is run. This type of programming approach is often called general programming as the program is generic enough to receive any two different values each time it is run.

Pseudo-code To Add Two Numbers Using Python Programming Language

num1 = Receive First Input Number From The User
num1 = Receive Second Input Number From The User
result = (num1) Added to (num2)
Print the (result) on the screen

We can see from the above psuedo code that this is a simple program that receives two numbers from the user, adds them and print their results back on the screen. The above pseudo code gives us a nice little framework on how to write our program. The same pseudo-code can now be used to write a program to add two numbers using any programming language and not just Python!

Now that we have our problem broken down and pseudo code written, it is time for us to replace the pseudo code with actual Python programming code instructions.

Python Program To Add Two Numbers And Print Its Result

Fire up your Python IDLE interpreter and start typing in the code along with me for you to be able to understand this program better:

Python 3.5.2 (default, Oct  8 2019, 13:06:37) 
 [GCC 5.4.0 20160609] on linux
 Type "copyright", "credits" or "license()" for more information.
>>>

Once in our python interpreter, let us start typing in our Python program commands. The first thing we need to do according to the pseudo code written above is the receive the first input number from our user. In Python program, the instruction code to be used to receive a value from its user is by calling the input() function. Input function will accept a string as its parameter that will be displayed to the program user when the program is run. So, with this knowledge, our first line of the Python program to add two numbers will be:

>>> num1 = input('Enter the first number\n')
Enter the first number
10
>>> 

As you can see from the above code block, we have used the input() function to prompt our program user with the string “Enter the first number“. We are also saving the value entered by the user to a Python variable called num1.

The input function will then prompt with the above string and wait until the user enters a number. In the above code snippet, I had entered a value of 10 which is now stored in the variable num1.

In a similar way, we will write the next line of code which will prompt the user to enter a second input number that is to be added to the first number. This is achieved with the following piece of code:

>>> num2 = input('Enter the second number\n')
Enter the second number
20
>>> 

Again over here, I have entered my second number as 20 when prompted.

Now that we have the two numbers in our Python variables num1 and num2, it is time add them to get the final result that we are going to store in our third Python variable called result. This is achieved using the following Python statement:

>>> result = int(num1) + int(num2)
>>>

So from the above python code, we have now added the numbers num1 and num2 using the Python arithmetic operator “+” and the typecast operator called “int()“. We had to use the typecast operator int because by default all inputs from the user into a python program will be interpreted and stored as a string. We can check this by issuing the following command in the interpreter:

>>> print(num1)
10
>>> type(num1)
<class 'str'>
>>> 

So, by calling the typecast operator int, we are converting this string value to an integer value.

>>> type(int(num1))
<class 'int'>
>>> 

finally stored the end result in a new variable called result. Since we have not issued a Python command to print the value of result, nothing gets printed on the IDLE prompt yet. So, the final step is exactly that. To print the value of the result variable onto the screen. This is achieved using another Python function called the print function.

>>> print (result)
30
>>>

Here is the full program that we can store in a file called add2num.py and run it using the command python3 add2num.py everytime we want to add any two numbers!

num1 = input('Enter the first number\n')
num2 = input('Enter the second number\n')
result = int(num1) + int(num2)
print (result)

This concludes our Python program to add two numbers.

Additional Side Notes On Python Programming Language:

Python is an interpreted programming language that gets interpreted and executed on the fly and hence the program written in Python do not need to be compiled like in the case of a C or Java programming language.

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Blinking An LED Connected To GPIO Pin Of Raspberry Pi Using Python

Introduction

If you are just getting started with Raspberry Pi, connecting a simple LED to one of the GPIO pins of a Raspberry Pi and controlling it using software program that you write will give you a very good grasp of how a computer hardware and its program works internally. You will realize how you can control various aspects of a computer hardware using software, how a computer works at the bit level, how to write Python programs to control hardware and more.

In summary, working on getting an led connected to a GPIO pin of your Raspberry Pi will help you in understanding the fundamentals of a computer architecture and computer science in general.

Raspberry Pi 3B

What You Will Learn From This Project?

Connecting an LED to the GPIO pins of a Raspberry Pi to control it is a simple Beginner Raspberry Pi Project that lets you learn more about:

  • Raspberry Pi hardware internals
  • General Purpose Input/Output (GPIO) pins of a Raspberry Pi
  • Raspberry Pi Register Set
  • Ohm’s Law
  • Python Programming
  • Python Library – Raspberry Pi GPIO library
  • The working of an Light Emitting Diode (LED)

What Hardware Is Required To Set Up A Blinking LED Project?

This a very simple, beginner friendly Raspberry Pi project that can be set up by anyone with minimal hardware or software knowledge. The hardware components required to set up this blinking LED project is also quite minimal. You need the following hardware components available with you to get it going:

  • Raspberry Pi Module
  • Solderless Breadboard
  • Keyboard
  • Monitor
  • Raspberry Pi Power Supply
  • SD Card with working Raspbian OS
  • Jumper wires for rigging up the circuit
  • LED
  • Resistor (1K Ohm)
  • Multimeter

Theory Behind How The Raspberry Pi Blinking LED Project Work

When you look at the Raspberry Pi board, you will see a bunch of pins protruding out. Among these, there is a row of 40 pins located on one side of the board as shown in the image below.

If you look closely enough in the above image, you will notice the label “GPIO” written right under it. These pins are called the GPIO pins or General Purpose Input Output pins. What the name GPIO implies is that these pins do not have any fixed functionality within the board and hence can be used for general purposes. It means that we can connect our LED into one of these pins and can turn it ON or OFF using these pins. But how?

How to control the Raspberry Pi GPIO pins programmatically?

Raspberry Pi 3 board runs on Broadcom’s ARM CPU chipset BCM2837. Among many other things, this processor chipset has a built in GPIO controller aka General Purpose Input Output controller. The 40 GPIO pins header shown in figure 1 is connected to 40 controllable pins of the GPIO controller. Now, we can control each of these pins individually by programming the appropriate registers inside this GPIO controller.

To understand how to program each of these pins using GPIO controller, we need to look into the Technical Reference Manual or datasheet of the Broadcom ARM chipset BCM2837.

In the BCM2837 SOC (System On Chip aka CPU) datasheet linked above, if we jump into page 89 we come across a dedicated chapter talking about General Purpose Input Output (GPIO). If we go through this chapter, we can learn about all the GPIO registers available and figure out the GPIO registers we need to program to turn ON or OFF the LED we are going to connect to the Raspberry Pi 3 GPIO pins.

As the name implies, GPIO pins can be configured as either an Input pin or an Output pin. When we configure a GPIO pin as an input pin, we are sending data bit (either 0 or 1) into the Raspberry Pi BCM2837 SOC i.e. data signal is sent from outside the board to inside the board (hence the name input). On the other hand, if we configure the Raspberry Pi GPIO pin as an output pin, the board will send the data bit signal (either 0 or 1) from inside the board to the outer world where any device connected to it will receive this signal.

So, if we want to control an LED that is connected to one of the Raspberry Pi’s GPIO pin, we need to configure that pin as a GPIO OUT pin (aka output pin) so that we can send an electrical signal from the Raspberry Pi board to the external LED connected to this pin.

The configuration of a GPIO pin to be an INPUT or OUTPUT pin is controlled by programming the GPIO Controller Register called GPIO Function Select Register (GPFSELn) where n is the pin number.

So for example, if we choose to use the GPIO8 pin to control the LED, i.e. we connect our LED to GPIO 8 pin, we need to program the GPFSEL register for the GPIO 8 pin and configure it as an Output pin. When we check the datasheet at page 91 and 92, we notice that GPIO pin is configured by setting the bits 26 to 24 in the GPFSEL register (that is field name FSEL8). And from the datasheet, we also find that to set the pin as an output pin, we need to set its value as 001 i.e. bit 26 is set to 0, bit 25 is set to 0 and bit 24 is set to 1.

So, if we can somehow set these values in the GPFSEL register using a programming language such as Python, we will be able to start controlling the LED connect to this pin!

If this is all overwhelming to you, do not worry. We will not have to scratch our head a lot for now as we can simply make use of Raspberry Pi’s GPIO Python library that helps us in making most of this work for us. But I just wanted to explain to you as to what this GPIO Python library is doing under the hood.

How To Connect An LED To Raspberry Pi GPIO?

Designing The Circuit

In order to connect an LED to GPIO pin 8 of Raspberry Pi, we need to first design and understand how the circuit is going to work.

Can we connect an LED directly to a Raspberry Pi GPIO pin without a resistor?

The answer is No. Raspberry Pi provides 3.3 Volts of power on its GPIO output pin according to Raspberry Pi datasheet specification. However, if we take a look at a standard LED, we notice that it normally operates at a much lower voltage. If we look at an LED specification, we notice that a typical LED usually operates at just 1.7 Volts and draws 20 mA. So, if we need to connect this LED to the GPIO pin of our Raspberry Pi, we need to bring down the voltage delivered by the pin to our LED to operate at or under 1.7V. How to do that? We connect a resistor in series with our LED so that the 3.3 Volts GPIO output of Raspberry Pi gets split between the resistor and our LED. By choosing a right value of the resistor such that it consumes 1.6 Voltage, we can ensure that LED finally gets only 1.7 Volts.

Calculating the resistor value to connect with LED and Raspberry Pi GPIO

In order to calculate the value of resistor that we should be using, we make use of the Ohm’s Law.

Ohm’s Law is defined using the equation:

V = I/R where V is the voltage, I is the current and R is the resistor value.

So, if we want to have V=1.6 Volts consumed by our resistor so that the current coming from GPIO pin is at I=20 mA, we need to connect a resistor whose value is:

1.6 = (20 mA)/R

or R = 80 Ohms (or approx 100 Ohms)

So, we choose a resistor of value 100 Ohms connected in series with our resistor to ensure that we only get 1.7 Volts and 20 mA of current, the optimum operating values as required by our LED.

A 100 Ohm resistor is identified by the color bands: Brown, Black & Brown.

Hook up the led through 100 Ohm resistor to GPIO 8 pin of Raspberry Pi as shown in the figure below:

Note that when you are hooking up the LED, the terminal pin that is longer is positive. Once you have connected as shown in the figure, it is now time to program the Raspberry Pi GPIO controller to start controlling the LED to turn ON or OFF.

We will be using Python to program our Raspberry Pi GPIO controller. Now, the simplest way to program this is by making use of the Python GPIO library.

To install the Python Raspberry Pi GPIO module, open up your linux terminal and type the following command.

sudo apt-get install python-rpi.gpio python3-rpi.gpio

Now the above command will install the required Python GPIO library module onto our Linux development machine. Once successfully installed, It is now time to start programming the Raspberry Pi GPIO controller.

We will be toggling our GPIO pins at 1 second intervals such that our LED will turn ON and OFF forever until the Python program we write will be terminated i.e., we will be running the code to perform infinite loop of toggling the GPIO 8 pin ON and OFF.

Create a new file on your computer by typing the following command in the terminal:

touch blinky.py

This should create our new program file called blinky.py

Open up this file using nano editor by typing the following command in the terminal:

nano blinky.py

Now that the file is opened, it is time to start writing our program to control the GPIO Pin 8 using Python GPIO library module.

First thing first, we will import the Python GPIO library module using command:

import RPi.GPIO as GPIO

Next, we will import python time library to perform 1 sec sleep operation between each GPIO toggle

from time import sleep

Next, we need to configure our GPIO library to use our GPIO physical pin numbering as seen on the Raspberry Pi board physically:

GPIO.setmode(GPIO.BOARD)

This ensures that when we say GPIO pin 8 in the program, it actually maps to the GPIO Pin 8 seen on the Raspberry Pi board.

Next, configure GPIO pin 8 to be a GPIO Out pin and set its initial output value to be low:

GPIO.setup(8, GPIO.OUT, initial=GPIO.LOW)

Finally we will start an infinite loop in Python such that we turn ON the GPIO 8 (by setting it HIGH) or turn it OFF (by setting it LOW) after every 1 second delay. This is achieved using the program below:

while True: # Infinite loop
    GPIO.output(8, GPIO.HIGH) # Turn GPIO 8 pin on
    sleep(1)                  # Delay for 1 second
    GPIO.output(8, GPIO.LOW)  # Turn GPIO 8 pin off
    sleep(1)                  # Delay for 1 second

That’s it, this should be all the program that we need to type in our blinky.py file and run it using the command:

python3 blinky.py

This should start turning your LED ON and OFF every second!

Here is the full code for your reference:

import RPi.GPIO as GPIO
from time import sleep

GPIO.setmode(GPIO.BOARD)
GPIO.setup(8, GPIO.OUT, initial=GPIO.LOW)

while True: # Infinite loop
    GPIO.output(8, GPIO.HIGH) # Turn GPIO 8 pin on
    sleep(1)                  # Delay for 1 second
    GPIO.output(8, GPIO.LOW)  # Turn GPIO 8 pin off
    sleep(1)                  # Delay for 1 second

This should conclude our tutorial on how to get a simple LED connected to a General Purpose Input/Output (GPIO) pin turning ON and OFF using a Python program that makes use of Python Raspberry Pi GPIO library. There can be many variants to this such as using other GPIO pins, connecting more than one LEDs to multiple GPIO pins and controlling them all in different ways to display interesting patterns on the LEDs. If we are even more curious, we can also figure out a way to control the BUILT-IN LEDs that are already present on our Raspberry Pi boards to bypass their current usage and be used for by own programs for our purposes.

We will dwell into these and many other interesting ways to make use of our Raspberry Pis to understand and learn more about the computer hardware, its architecture and much more in our future articles.