• Getting Started with MicroPython on ESP32 and ESP8266
• Install uPyCraft IDE:
  • Install uPyCraft IDE – Windows PC Instructions
  • Install uPyCraft IDE – Mac OS X Instructions
  • Install uPyCraft IDE – Linux Ubuntu Instructions
• Flash/Upload MicroPython Firmware to ESP32 and ESP8266

Mathematical Operators

Micropython can perform mathematical operations. The following table shows the mathematical operators supported:

In the Shell, try several operations to see how it works. For example:

>>> 2+2*9-317>>> 28594/231212.36765>>> 214522236/7.52.860297e+07>>> 23//211>>> 25%31

You can perform other mathematical operations if you import themath module, like square root, trigonometric functions, logarithm, exponentiation, etc..

Relational Operators

You can make comparisons using relational operators. These compare the values on either sides and show the relation between them.

Try several comparisons and test the result:

>>> 2 == 3False>>> 4 == 4True>>> 3 > 2True>>> 489808234 != 2223True>>> 4.5 >= 4.5True

Assigning Values to Variables

In Python you don’t need to declare what type each variable is. If you’re used to program your boards using Arduino IDE, you know that you need to declare the type of a variable when creating a new variable. There isn’t such thing in Python.

Variables are simply a storage placeholder for values: number or text. To assign a value to a variable you use the equal sign (=), with the variable name on the left and the value on the right.

For example, to create a variable to hold the GPIO number where an LED is connected to, you can simply type the following:

led_pin = 23

In the Arduino IDE, you would have something like:

const int led_pin = 23;

As you can see, Python is much simpler than programming in C (in Arduino IDE).

Note: the names you give variables can’t have spaces and are case sensitive, soled_pin is different fromLED_PIN orLed_Pin.

Data Types

Variables can store several types of values, not just whole numbers. That’s wheredata types come in. A data type is a classification of a value that tells what operations can be done with the value and how it should be stored.

The following table shows the data types we’ll use most often in our projects.

Let’s create variables with different data types:

>>> a = 6>>> b = 95.32>>> c = 'Hello World!'>>> d = True

• The first value assigned toa, is aninteger, which is a whole number.
• Theb variable contains afloat value, which is a number with a decimal.
• The third value, ‘Hello World!’, is astring, which is a series of characters. A string must be put inside single (‘Hello World!’) or double quotation (“Hello World!”) marks.
• Finally,dis aBoolean, which is a type that can only take either True or False.

There is a function to check the data type of a variable: thetype()function. This function accepts as argument the variable you want to check the data type.

type(variable)

For example, after declaring the variables in the previous examplea,b,c, andd, you can check its data type. For example, if you type:

>>> type(a)

It returns:

<class 'int'>

This tells thata is an int (integer). Experiment with the other variables and you should get:

>>>type(b)<class 'float'>>>>type(c)<class 'str'>>>>type(d)<class 'bool'>

print() Function

Theprint() function prints the message between parentheses into the Shell. This is specially useful in our projects to debug the code and keep track of what’s going on. For example:

>>>print('LED is on')LED is on

Comments

Comments in Python start with the hash character (#) and continue to the end of the line. A comment is useful to add “notes” in your program or to tell anyone who reads the program what the script does. This doesn’t add any functionality to your program. For example:

# This is just a comment

Because in MicroPython we are working under constrained conditions, there are occasions in which you should avoid adding comments to save space on the ESP memory.

Conditional Statements

To write useful programs, you’ll probably need to perform different actions depending on whether a certain condition is True or False. We’re talking about conditional statements. They have the following structure:

if <expr1>:  <statement1>elif <expr2>:  <statement2>elif <expr3>:  <statement3>(...)else:  <statementn>

<expr> is a Boolean expression and it can be eitherTrue orFalse. If it is True, the <statement> right after it is executed. The <statement> should be indented so that Python knows what statement belongs to each expression.

Theelif statement stands for else if and runs only if the firstif condition is not True.

Theelse statement only runs if none of the other expressions are True.

There’s no limit to the number ofelif statements in a program. It’s also not necessary to include anelse clause, but if there is one, it must come at the end.

In the Arduino IDE, we use {} curly brackets to define code blocks. With MicroPython, we use indentation. Additionally, you need to use a colon: after each expression. Contrary to the Arduino IDE, the expression doesn’t need to be inside parentheses.

Important: Python’s standard indentation is 4 spaces. In MicroPythonindentation should be only 2 spaces to fit more code into the microcontroller memory.

While and For loops

Loops allow you to execute a block of code multiple times for as long as a condition is met. There are two kinds of loops:while andfor loops. For example, you can print all numbers from 1 to 10 with awhile loop:

number = 1while number <= 10:  print(number)  number = number + 1

The code that belongs to the while loop, indicated by the indentation, is executed as long as the value in the number variable is less than or equal to (<=) 10. In every loop, the currentnumber is printed and then 1 is added to it.

You can also print numbers from 1 to 10 using afor loop, like this:

number = 1for number in range(1, 11):  print(number)

Thefor loop is executed as long as the value in the number variable is within the range of 1 and 11. Therange() function automatically assigns the next value to thenumber variable, until 1 below the final number you specify.

You should use a for loop when you want to repeat a block of code a certain number of times. Use a while loop when you want to repeat code until a certain condition is no longer met. In some situations, you can use either one, oftentimes one is more suitable than the other.

Similar to the conditional statements, thefor andwhile Boolean expressions should have a colon: right after them, and the expressions to be executed should be indented.

User-defined Functions

To define a new function, you use the worddef followed by the name you want to give the function and a set of parentheses (and arguments inside, if necessary). After the parentheses you add a colon: and then tell the function what instructions to perform. The statements should be indented with 2 spaces (in MicroPython). For example:

def my_function(<arg1>, <arg2>, ...):  <statement>  (...)  return

For example, a function that converts the temperature in Celsius to Fahrenheit could be the following:

def celsius_to_fahrenheit(temp_celsius):   temp_fahrenheit = temp_celsius * (9/5) + 32   return temp_fahrenheit

Thecelsius_to_fahrenheit() function accepts as argument a temperature in Celsius (temp_celsius). Then, it does the calculation to convert the temperature. Finally, it returns the temperature in Fahrenheit (temp_fahrenheit).

Note: functions don’t necessarily need to return something. They could just perform some work without the need to return anything.

Classes and Objects

Python is an Object-Oriented Programming (OOP) language. There are two important concepts you need to understand about OOP: classes and objects.

A class is a blueprint for objects. It defines a set of attributes (data and functions) that characterize an object. The functions inside of a class are called methods. Classes are defined by the keywordclassfollowed by the name of the class. For example:

class MyClass:  (...)

Note: by convention, classes’ names in Python should be CapWords. However, you can give whatever name you want.

An object is an instance of a class. It’s simply a collection of data and methods into a single entity. Through the object, you can use all functionalities of its class. Confused? Let’s take a look at a simple example.

If we would like to define several persons in a Python program using the same attributes, we can think of the term person as a class. We may want to define a person using attributes like name, age, country, etc.

So, we can create a class calledPerson. Our class will have the following attributes:name,age, andcountry. You can add as many attributes as you want. We’ll also create a function (method) that prints a description of the person based on its attributes:

class Person:  name = ""  age = 0  country = ""  def description(self):    print("%s is %d years old and he is from %s." %(self.name, self.age, self.country))

As you can see, we define a new class by using the keywordclass, followed by the name we want to give to the class.

Inside thePerson class, we define several variables to hold values. By default thename andcountry are empty strings, and theage is 0. Then, we also define a function (method) that prints all the variables values into the Shell.

All functions inside a class should have theself parameter as argument and other arguments, if needed.

The self  parameter refers to the object itself. It is used to access variables that belong to the class. For example, to access thename variable inside the class, we should useself.name.

Now that we’ve create a class, we can create as manyPerson objects as we want by using that class. ThePerson object will have a name, age, and country. We’ll also be able to print its description using thedescription() method.

For example, to create a newPerson object calledperson1:

>>> person1 = Person()

Set the object’s properties

To set thename,age, andcountry of theperson1 object. You can do it as follows:

>>> person1.name = "Rui">>> person1.age = 25>>> person1.country = "Portugal"

Calling methods

Later in your code you can use the createddescription()method on any Person object. To call thedescription() method on theperson1 object:

>>> person1.description()

This should print the following:

Rui is 25 years old and he is from Portugal.

You should now understand that you can create as many objects as you want using the same class and you are able to use the available methods with all the objects of that class.

The constructor method

Instead of having to define a class, and then set the object’s properties, which can be time consuming, you can use the constructor method inside your class.

The constructor method is used to initiate data as soon as an object of a class is instantiated. The constructor method is also known as __init__ method.  Using the __init__ method, thePerson() class looks as follows:

class Person():  def __init__(self, name, age, country):    self.name = name    self.age = age    self.country = country  def description(self):    print("%s is %d years old and he is from %s." %(self.name, self.age, self.country))

Then, to instantiate aPerson object with the same attributes we’ve defined earlier, we just need to do the following:

>>> person1 = Person("Rui", 25, "Portugal")

If you call thedescription() on theperson1 object, you’ll get the same result:

>>>person1.description()Rui is 25 years old and he is from Portugal.

Modules

A module is a file that contains a set of classes and functions you can use in your code – you can also call it library. To access the classes and functions inside that code, you just need to import that module into your code.

You can create your own modules, or use already created modules from the standard Python library. When it comes to MicroPython, it only comes with a small subset of the standard Python library, but it does come with a set of modules to control GPIOs, make networks connections and much more.

Importing modules/libraries is as simple as using:

import module_name

For example, to import themachine library that contains classes to control GPIOs, type the following:

import machine

In most programs you won’t need all the classes from one module. You may just want to import a single class. For example, to import only thePin class from themachine module:

from machine import Pin

Wrapping Up

In this tutorial we’ve just scratched the surface of Python basics that also apply to MicroPython. If you are used to program electronics using the Arduino IDE, you’ll find that MicroPython has a much simpler and user-friendly syntax. Let’s just summarize some of the main differences between your Arduino sketches and programs in MicroPython:

• You don’t use semicolon; at the end of a statement
• After Boolean expressions in conditional statements and loops, you use a colon:
• To define code blocks use indentation instead of curly brackets {}
• When creating a variable, you don’t need to define which data type it is – you don’t need to declare a variable
• Indentation in MicroPython is 2 spaces

Recommend reading:MicroPython Programming with ESP32 and ESP8266 eBook

We hope you’ve found this article about the MicroPython basics syntax useful. We’ll be adding tutorials about programming the ESP32 and ESP8266 using MicroPython very soon. So, stay tuned andsubscribe the RNT blog!

Thanks for reading.

18 thoughts on “MicroPython Programming Basics with ESP32 and ESP8266”

1. Nice work

   Reply

   • Thanks 🙂

     Reply

2. Hi,

   Can we install Tensorflow in in ESP32 or esp8266 ?

   Would be interested if you can make any tutorial when you get a chance…

   Thx

   Reply

   • Hi Raj.
     We’re not planning adding any tutorials about Tensorflow in a near future.
     Regards,
     Sara 🙂

     Reply

3. Wonderfully written, easy to understand step by step introduction of the basics.

   What I would of liked to have seen is an example of actually creating a small module (Library).

   Reply

   • Hi.
     Thank you for your support.
     This is just a quick getting started guide, so we just included the most basic and essential stuff.
     Creating a module is indeed something really interesting. Maybe we’ll add a new tutorial about that in a near future.
     Regards,
     Sara 🙂

     Reply

4. Perfektne, praktické, jednoduché.
   MicroPython ma svoju budúcnosť a aj ESP32.
   Dakujem.
   ps: pošlem na cafe.

   Reply

   • Hi Dusan.
     You are right!
     Thank you so much for supporting our work.
     (Ďakujeme vám za podporu našej práce) (used Google translator).
     Regards,
     Sara

     Reply

5. Thanks for the article. I have been doing Arduino C++ on a NodeMcu 8266 and it is somewhat limiting. I am quite comfortable with Python and I want to give it a try.

   Does MicroPython support LIsts, Tuples and Dictionaries? If so, I’m in.
   Thanks

   Reply

   • Hi Henry.
     Yes, it does.
     In the following link you can see in more detail the differences between Python and MicroPython:http://docs.micropython.org/en/latest/genrst/builtin_types.html#
     Regards,
     Sara 🙂

     Reply

6. Hi. I really appreciate your work. I’m starting with uPython and your explanation was very helpful.
   Is there any simple GUI to control mi esp32 board ?

   Reply

7. Hi,
   I enjoy your tutorials. Thank you!
   I can get ESP32 programs to run in micro python on my Wroom board using uPycraft. However I do not understand how to permanently upload the equivalent of an hex file (as with AVR or Pic processors) so that the program runs by itself. Have I missed something or is this not possible? When I shutdown uPycraft the program stops working.

   regards,

   Colin

   Reply

   • Hi.
     Make sure that you are uploading the code to the board and not just running the code.
     Here’s a tutorial about upycraft:https://randomnerdtutorials.com/getting-started-micropython-esp32-esp8266/
     Regards,
     Sara

     Reply

     • Thank you Sara for your quick response!
       I did follow the tutorial but still cannot get the program to run by itself after re-setting. I renamed it ” main.py “and there is a boot.py in the device list. However boot.py is empty (?)
       Contents of boot.py:

       This file is executed on every boot (including wake-boot from deepsleep)

       #import esp
       #esp.osdebug(None)
       #import webrepl
       #webrepl.start()

       Surely it should contain some instructions?
       I am puzzled!

       regards and thanks for your patience,

       Colin

       Reply

       • Hi.
         It doesn’t necessarily need to have something on it. It can be empty without any problem.
         You need to make sure that the main.py file is on the device folder. Otherwise, it won’t run by itself.
         At the side bar, check that you have a main.py file on the device folder.

         It might also be an issue with your IDE, I’m not sure… You may want to try another IDE and see how it goes.
         We have a tutorial for Thonny IDE, and VS Code with the PyMakr extension:
         https://randomnerdtutorials.com/getting-started-thonny-micropython-python-ide-esp32-esp8266/
         https://randomnerdtutorials.com/micropython-esp32-esp8266-vs-code-pymakr/

         Regards,
         Sara

         Reply

         • Hi Sara,
           Thanks again for your reply.
           I have tried Thonny and this seems to work very well as it allows me to load the code onto the board. I now have an ESP32 reading from a DS18b20, displaying the result on an oled display, sending output to uart and also a flashing light. What more could I ask for?
           Many thanks for your help.

           best wishes,

           Colin

         • Great!
           I’m glad the issue was solved.
           Regards,
           Sara

8. I want to use a ESP32 to connect with a UHF readers, I want to use uPython for that, how I can call or import .h files from my main.py?

   Reply