ECE 40862 Lab 1 – Introduction to Python and – Digital Input and Output using GPIOs solution


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1. Overview
This assignment will familiarize you with the Python programming language and the Thonny
Python IDE editor, which we will use throughout the semester. Python is an easy-to-learn but
powerful programming language and is one of the fastest growing programming languages for
embedded systems. In this course, we will use MicroPython to program the ESP32 board.
MicroPython is a lean and efficient implementation of the Python3 programming language.
Before working with MicroPython on your board, you should acquaint yourself with Python.
2. Getting started with Python and MicroPython
The following sections describe various software installation procedures.
2.1. Install Thonny IDE on your own PC
Thonny is a Python IDE meant for learning programming. You can find more details about this
IDE and download it at Install the latest version (4.0.1). Installation
instructions for Windows, Linux, and Mac OS are provided on the above webpage. By default,
Thonny comes with Python 3.10 built in, so a separate installation of Python is not needed.
2.2. Install USB-Serial Driver on your host PC (Windows and Mac only)
Follow the guide available at to install the drivers for the USB to serial converter chip that the board uses to
communicate with your host PC. There are drivers for Windows and Mac computers available.
If you’re on Linux, the drivers are built in.
2.3. Flashing MicroPython on ESP32 (using Thonny)
The latest version of Thonny (4.0.1) comes preinstalled with the package ‘esptool’, which is a
Python-based, open source, platform independent, utility to communicate with the ROM
bootloader in ESP32. Esptool can be used to load MicroPython on your ESP32 board.
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2.3.1. Acquiring MicroPython Firmware
Download latest ESP32 firmware from As of today, the
latest available firmware is ‘esp32spiram-20220618-v1.19.1.bin’ (you can click this link
directly to download the firmware).
2.3.2. Thonny Setup and Flashing
• Plug in your ESP32 board to your computer using a USB-C cable, launch Thonny and
navigate to “Run > Configure Interpreter”.
• Under the “Which interpreter or device should Thonny use for running your code?”
label, select “MicroPython (ESP32)”.
• Select the COM port to which your ESP32 is connected under “Port” (see Figure 1).
Figure 1. Set the interpreter and port
• After setting the interpreter and the port, click on the link at the bottom: “Install or
Update MicroPython”. Select your device’s port again and browse for the MicroPython
firmware that you downloaded earlier for the “Firmware” field. If you are flashing
MicroPython on your board for the first time, then make sure that “Erase flash before
installing” is checked, then click “Install”, as shown in Figure 2.
Figure 2. Select the port and downloaded MicroPython firmware
Thonny will now erase any existing firmware, and then flash the new MicroPython
firmware on your ESP32, as you can see in Figure 3 and 4. This may take a few minutes.
After the firmware has finished installing, you may close all the open dialogs.
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Figure 3. Flashing progress
Figure 4. Thonny has completed flashing the firmware on the microcontroller.
• At the bottom of the Thonny window in the tab labeled “Shell”, you should see text that
resembles Figure 5.
Figure 5. MicroPython REPL ready for input
Your ESP32 board is now ready for programming.
3. Python warm up programming exercises
You DO NOT need to use ESP32 for this part. You can use the default python interpreter.
3.1. Character Input (Upload as
Write a program that asks the user to enter name and age. Print out a message that tells the year
the user will turn 100 years old.
Hint: Use input command to get user input
>>> python
What is your name? Xavier
How old are you? 25
Xavier will be 100 years old in the year 2094
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3.2. Lists and Conditional Statements (Upload as
Write a program to initiate a list of 10 numbers, print the list, and ask the user for a number
and return a list that contains only elements from the original list that are smaller than the
number given by the user.
>>> python
a = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
Enter number: 25
The new list is [1, 1, 2, 3, 5, 8, 13, 21]
3.3. Loops
3.3.1. While loop: (Upload as
Write a program to get the Fibonacci series between 0 to a user input number using a while
>>> python
How many Fibonacci numbers would you like to generate? 10
The Fibonacci Sequence is: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55
3.3.2. For loop: (Upload as
Write a program that generates a random number (0-10) and asks the user to guess it within
three chances. If user guesses correctly, print ‘You win!’, otherwise print ‘You lose!’
>>> python
Enter your guess:3
Enter your guess:2
Enter your guess:10
You win!
3.4. Dictionary (Upload as
Write a program to create a dictionary of 5 names and birthdays. Upon execution, it should ask
the user to enter a name, and return the birthday of that person back to them.
>>> python
Welcome to the birthday dictionary. We know the birthdays of:
Albert Einstein
Benjamin Franklin
Ada Lovelace
Whose birthday do you want to look up?
Benjamin Franklin
Benjamin Franklin’s birthday is 01/17/1706.
3.5. Class and Functions (Upload as
Write a program to create a Python class to find a pair of elements (indices of the two numbers)
from a given list of numbers whose sum equals a specific target number.
Use this list in your program: [10, 20, 10, 40, 50, 60, 70]
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Hint: You might create dictionaries of array index as keys and array item as values as you scan
through the array. Use conditional statements, loops, etc.
>>> python
What is your target number? 60
index1=1, index2=3
4. Digital input/output using GPIOs
This section explains how to get started with the Adafruit HUZZAH32 – ESP32 V2 Feather
board and how to program the board using MicroPython and Thonny IDE. The goal of this
experiment is to walk you through the embedded software development flow for the ESP32,
where you will learn how to use microcontroller I/O, the inputs and outputs, to sense and
actuate devices in the world outside the board.
The assignment is subdivided into two sections. In the first section, you will learn to implement
a simple LED blink program that will give you a high-level idea of how you can accomplish
the remaining labs. In the second section, you will interface two LEDs (Red and Green) and 2
Push Button Switches with the board and implement a simple pattern function using them.
The ESP32-PICO-MINI-02 module on the V2 Feather Board has 53 pins, many of which are
GPIO (general-purpose input/output) pins. However, the feather board has only 28 pins and
has its own ad-hoc pin numbering (marked e.g., A0, A1…) with many peripheral pins (like TX,
RX, SCL, SDA…) indicated on the board itself. You need to explore the ESP32-PICO-MINI02 datasheet and ESP32 Feather V2 board manuals and the board’s Pinouts to figure out the
mapping between physical chip pins and board logical pins.
4.1. Programming ESP32 using Thonny IDE
Before proceeding further, you should have completed installing any necessary software
(explained in Section 2) and flashed MicroPython on the ESP32 board. The implementation
procedure explained in this section demonstrates a typical procedure to run any program on the
4.2. Connect the Board to PC
Connect the board to your PC using the USB-C cable (just plug into the jack) and the Feather
will regulate the 5V USB down to 3.3V which will power the board. You can get more
information on starting MicroPython on your ESP32 board on this webpage:
4.3. Testing Thonny IDE Installation
Important: Before testing the installation, your ESP32 board needs to be flashed with
MicroPython firmware. Connect the board to your PC and open Thonny IDE. To test the
installation, you need to tell Thonny that you want to run MicroPython Interpreter and select
the board you are using.
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1. Go to Tools > Options and select the Interpreter tab. Select MicroPython (ESP32).
2. Select the device serial port
Figure 6. Thonny Interpreter and Port selection
Thonny IDE should now be connected to your board. The board will start and run the files
‘’ and ‘’ (if any) automatically and provide you a MicroPython REPL shell. A
read–eval–print-loop (REPL), also termed interactive top-level or language shell, is a simple,
interactive computer programming environment that takes single user inputs (i.e., single
expressions), evaluates (executes) them, and returns the result to the user, shown in Figure 8.
Figure 7. MicroPython startup on ESP32 in Thonny IDE
4.4. Using the REPL
Once you have a prompt, you can start experimenting! Anything you type at the prompt will
be executed after you press the Enter key. MicroPython will run the code on the board that you
enter and print the result (if there is one). If there is an error with the text that you enter, then
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an error message is printed. You can find more information on REPL at (MicroPython execution is
similar in ESP8266 and ESP32).
Figure 8. Experimenting with REPL
Type the command help() in the Shell and see if it responds back. If it responded back,
everything is working fine.
Figure 9. Testing the REPL
4.5. First Program on the ESP32
In the EDITOR of the Thonny IDE, write your first ‘Hello World’ program and save it on the
board as The IDE asks for location to save the file, Select MicroPython device to
save the file on the flash memory on the board, as shown in Figure 11. Pressing Ctrl+D or
selecting Run > Send EOF/Soft Reboot in Thonny will perform a soft reboot of the board and
as mentioned earlier, it will run and you will see the output on the MicroPython shell.
You can also run the program from the shell by calling the following command, which
will run the code inside and give you output on the shell, both of which are shown in
Figure 12. Similarly, any code you write for your labs, you can save them on the board and
import your program module in MicroPython shell to run the code.
import main
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Figure 10. Saving file on ESP32 board
Figure 11. Reboot and Running
4.6. The internal filesystem
Since ESP32 Feather has 8MB flash memory, a default filesystem will be generated upon first
boot, which uses the FAT format and is stored in the flash after the MicroPython firmware.
You can open any file already stored inside the board using Thonny IDE, modify it and save it
back on the board. More details on working with the internal filesystem are available at this
5. ESP32 Programming Exercises
5.1. Simple Blink Program (
The example source code below blinks the Red LED on the ESP32 V2 Feather board 5 times
with the interval of roughly 0.5 seconds. Use this source code and save as file on your
board and perform a soft reboot. Use the Feather V2 board Pinouts to figure out the pin X
connected to the red LED on the board.
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5.2. NeoPixel Color Changes based on Switch Presses (
Now that you have gone through the warm-up program above, you can finally get to the actual
problem statement for Lab 1. You will use the onboard user push button and the onboard
NeoPixel LED for this lab. The switch is considered to be ON when it is pushed down and OFF
when it is released. Start your program by lighting up the NeoPixel to red. When the switch is
ON (pressed), the NeoPixel should turn green. When the switch is OFF (released), the NeoPixel
should go back to being red.
In addition, you must determine the number of times the switch is pressed from the start of
the program. If the switch is pressed 5 times, when it is released, the NeoPixel should turn
OFF and your program should exit with a message on the MicroPython shell ‘You have
successfully implemented LAB1!’ and exit to the shell.
6. Submission
Make sure you follow these instructions precisely. Points will be deducted for any deviations.
You need to turn in your code on Brightspace. Please create a directory named username_lab1,
where username is your CAREER account login ID. Inside this directory, create two more
directories, part1 and part2.
• Put all the files created in section 3 (Python programming exercise) in part1.
• Put all the files created in section 5 in part2.
NOTE: These directories should contain only the source code files, i.e., no executables, no
temporary files, etc.
• Zip the parent directory (i.e., username_lab1) and name it as and
upload the .zip file to Brightspace.
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[1] Getting started with MicroPython on the ESP32
[2] ESP32 PICO MINI 02 Datasheet
[3] ESP32 Technical Reference Manual
[4] Adafruit HUZZAH32 – ESP32 V2 Feather Online Manual
[5] Adafruit ESP32 Feather Pinouts:
[6] MicroPython GitHub
[7] REPL
[8] Thonny IDE