Python on Microcontrollers: A Comprehensive Guide to Writing Embedded Software with MicroPython

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Python on Microcontrollers: A Comprehensive Guide to Writing Embedded Software with MicroPython

MicroPython brings Python to microcontrollers, enabling rapid prototyping and easy hardware control. It supports various boards, offers interactive REPL, and simplifies tasks like I2C communication and web servers. Perfect for IoT and robotics projects.

Feb 27, 2023

Python on Microcontrollers: A Comprehensive Guide to Writing Embedded Software with MicroPython

Python on microcontrollers? It’s not just a buzzword anymore! As a tech enthusiast, I’ve been fascinated by the potential of running Python on tiny devices. Let me share what I’ve learned about this exciting world of embedded programming.

First things first, what’s MicroPython? It’s a lean and efficient implementation of Python 3, specifically designed for microcontrollers and embedded systems. Imagine having the simplicity and power of Python in your pocket-sized projects!

Why should you care? Well, if you’re already familiar with Python, you’ll feel right at home. No need to learn a new language or wrestle with complex C code. Plus, it’s perfect for rapid prototyping and getting your ideas up and running quickly.

Let’s dive into some of the cool features of MicroPython. It comes with a interactive REPL (Read-Eval-Print Loop), which means you can type commands and see results instantly. This is super helpful for debugging and experimenting on the fly.

MicroPython also includes a subset of the Python standard library, so you can use many familiar modules like math, random, and even time. But it doesn’t stop there – it also provides hardware-specific modules for controlling pins, sensors, and other peripherals.

Now, you might be wondering which boards support MicroPython. The good news is that there are plenty of options! Some popular choices include the PyBoard, ESP8266, and ESP32. I personally love tinkering with the ESP32 – it’s affordable, powerful, and has built-in Wi-Fi and Bluetooth.

Let’s get our hands dirty with some code. Here’s a simple example to blink an LED using MicroPython on an ESP32:

from machine import Pin
import time

led = Pin(2, Pin.OUT)

while True:
    led.on()
    time.sleep(0.5)
    led.off()
    time.sleep(0.5)

Pretty straightforward, right? This code creates a Pin object for the onboard LED (usually connected to GPIO 2), then toggles it on and off every half second.

But MicroPython isn’t just about blinking LEDs. You can do some seriously cool stuff with it. For instance, let’s create a web server that displays sensor data:

import network
import socket
from machine import Pin, ADC
import time

# Connect to Wi-Fi
ssid = 'YourWiFiName'
password = 'YourWiFiPassword'
station = network.WLAN(network.STA_IF)
station.active(True)
station.connect(ssid, password)

while not station.isconnected():
    pass

print('Connected to Wi-Fi')

# Set up temperature sensor
adc = ADC(Pin(34))
adc.atten(ADC.ATTN_11DB)

# Create a socket server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('', 80))
s.listen(5)

while True:
    conn, addr = s.accept()
    print('Got a connection from %s' % str(addr))
    request = conn.recv(1024)
    
    # Read temperature
    temp = adc.read() * 0.1 - 50  # Convert ADC value to Celsius
    
    # Create HTML response
    response = """HTTP/1.1 200 OK
Content-Type: text/html

<html>
    <body>
        <h1>ESP32 Temperature Sensor</h1>
        <p>Temperature: {:.1f} C</p>
    </body>
</html>
""".format(temp)

    conn.send(response)
    conn.close()

This script sets up a simple web server that reads data from a temperature sensor and displays it on a webpage. Pretty neat, huh?

One of the things I love about MicroPython is how it simplifies working with hardware. Take I2C communication, for example. Here’s how you’d read data from an I2C device:

from machine import I2C, Pin

i2c = I2C(scl=Pin(22), sda=Pin(21))
devices = i2c.scan()

if devices:
    print("I2C device found at address: 0x{:02x}".format(devices[0]))
    data = i2c.readfrom(devices[0], 4)  # Read 4 bytes from the device
    print("Data:", data)
else:
    print("No I2C device found")

This script scans for I2C devices, and if it finds one, it reads some data from it. It’s that simple!

But MicroPython isn’t just about hardware control. You can also use it for more complex tasks, like machine learning! Yes, you heard that right. With libraries like ulab (a NumPy-like library for MicroPython), you can perform numerical computations and even implement simple ML algorithms on your microcontroller.

Here’s a basic example of using ulab to perform matrix multiplication:

import ulab as np

# Create two matrices
a = np.array([[1, 2], [3, 4]])
b = np.array([[5, 6], [7, 8]])

# Multiply matrices
result = np.dot(a, b)

print("Result:")
print(result)

This is just scratching the surface of what’s possible with MicroPython. You can build IoT devices, robotics projects, home automation systems, and so much more.

Of course, MicroPython isn’t without its challenges. Memory management can be tricky on resource-constrained devices, and you might need to optimize your code more than you would for a desktop Python application. But the trade-off in ease of use and rapid development is often worth it.

One tip I’ve learned the hard way: always use with statements when working with files on a microcontroller. It ensures that files are properly closed, even if an exception occurs. Here’s an example:

with open('data.txt', 'w') as f:
    f.write('Hello, MicroPython!')

This might seem trivial, but on a microcontroller, leaving files open can lead to corruption of your filesystem. Trust me, you don’t want to debug that issue in the field!

Another cool feature of MicroPython is its ability to run multiple “threads” using _thread module. While it’s not true multithreading (Python’s GIL still applies), it can be useful for certain tasks. Here’s a simple example:

import _thread
import time

def second_thread():
    while True:
        print("I'm running in parallel!")
        time.sleep(1)

_thread.start_new_thread(second_thread, ())

# Main thread
while True:
    print("Main thread still running")
    time.sleep(2)

This script creates a second “thread” that runs alongside the main one. It’s great for tasks that need to run continuously without blocking the main program flow.

As you dive deeper into MicroPython, you’ll discover a whole ecosystem of libraries and tools. There’s upip, MicroPython’s version of pip, which lets you install packages directly on your device. And don’t forget about tools like ampy and rshell, which make it easier to transfer files to your microcontroller.

In conclusion, MicroPython opens up a world of possibilities for embedded development. It combines the simplicity of Python with the power of microcontrollers, making it accessible to beginners while still being powerful enough for complex projects. Whether you’re building a simple IoT sensor or a complex robotics system, MicroPython has got you covered. So grab a board, fire up that REPL, and start creating!