Micropython CheatSheet

Micropython is a lightweight implementation of Python 3 optimized to run on microcontrollers and embedded systems with limited resources.

Introduction

Install Micropython on a device

Flash the Micropython firmware onto a device (like the ESP32 or ESP8266) using tools like esptool.py:

esptool.py --chip esp32 --port /dev/ttyUSB0 write_flash -z 0x1000 firmware.bin

Verify the installation

Connect the microcontroller to your PC and use a serial terminal like PuTTY or Minicom to verify the installation.

screen /dev/ttyUSB0 115200

Read the version

To check the installed version of MicroPython.

import sys
print(sys.version)

Basic commands in REPL

Start REPL

Once connected, start the interactive REPL (Read Eval Print Loop) terminal with the following line:

screen /dev/ttyUSB0 115200

Exit REPL

To exit the REPL, press Ctrl+A, followed by Ctrl+D.

Execute a command

You can run commands directly:

>>> print("Hello, Micropython")

Run a script

To run a script in MicroPython, you first need to upload it to the device, and then use the following command in the REPL (Read-Eval-Print Loop).

import main

File management

List files in the system

View the files stored on the microcontroller.

import os
os.listdir()

Upload a file to Micropython

You can use ampy to upload files from your computer.

ampy --port /dev/ttyUSB0 put my_script.py

Create a file

Create a file and write content to it.

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

Read a file

Read the content of a file.

with open('file.txt', 'r') as f:
    print(f.read())

Delete a file

Delete a specific file:

os.remove('my_script.py')

Hardware control

GPIO (Input/Output)

Digital outputs

To configure an output pin, such as turning on an LED on pin 2:

from machine import Pin
led = Pin(2, Pin.OUT)
led.value(1)  # Turn on
led.value(0)  # Turn off

Digital inputs

Configure a pin as input, for example, to read the state of a button.

button = Pin(4, Pin.IN, Pin.PULL_UP)
button_state = button.value()  # Read button value

Generate a PWM signal

Use PWM (Pulse Width Modulation) to control devices like motors or the brightness of an LED.

from machine import Pin, PWM
pwm = PWM(Pin(15))
pwm.freq(500)  # Frequency of 500Hz
pwm.duty(512)  # 50% duty cycle

Peripherals

UART (Serial communication)

Initialize UART communication

Set up a UART port for serial communication.

from machine import UART
uart = UART(1, baudrate=9600, tx=17, rx=16)
uart.write('Hello, UART!')

Read data from UART

data = uart.read(10)  # Read up to 10 bytes

I2C

Initialize I2C communication

Set up I2C pins and communicate with sensors or displays.

from machine import I2C, Pin
i2c = I2C(scl=Pin(22), sda=Pin(21))
devices = i2c.scan()  # Search for connected devices

Read and write to an I2C device

Read from an I2C device:

data = i2c.readfrom(0x3C, 2)  # Read 2 bytes from the device with address 0x3C

Write data:

i2c.writeto(0x3C, b'\x01\x02')  # Send 2 bytes

Data manipulation

Type conversion

You can convert between data types, such as integers and strings.

number = int("123")  # String to integer
text = str(123)      # Integer to string

String formatting

Use Python’s string formatting to print data in a custom way.

age = 21
print("I am {} years old".format(age))

Working with lists

Micropython supports list operations, just like in Python.

my_list = [1, 2, 3]
my_list.append(4)  # Add an element
my_list.remove(2)  # Remove an element

Internet connection

Connect to Wi-Fi

Connect to a Wi-Fi network.

import network

ssid = 'your_ssid'
password = 'your_password'
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(ssid, password)

while not wlan.isconnected():
    pass

print('Connected to', ssid)
print('IP Address:', wlan.ifconfig()[0])

Send data to an HTTP server

Send a GET request to a server.

import urequests

response = urequests.get('http://your-api.com/data')
print(response.text)

Debugging

Print to console

Use print to debug and see values at runtime.

print("The value of the LED is:", led.value())

Exception handling

Basic exception handling.

try:
    # Code that may raise an exception
    value = 10 / 0
except ZeroDivisionError:
    print("Error: Division by zero")

Check available memory

Use gc to check available memory and clean up accumulated garbage.

import gc
gc.collect()  # Force garbage collection
free_memory = gc.mem_free()  # Check available memory