MicroPython

A collection of sample code extracts for commonly used tasks within MicroPython when used on a microprocessor such as the RP2040 (Raspberry Pi Pico), ESP32, or Microbit.

Raspberry Pi Pico pinout diagram

My current recommended IDE for MicroPython is Thonny. It has excellent hardware support for the commonly used devices. Check this connection guide for the Raspberry Pi Pico.

Operate an LED or simple device

import machine, time

# Using GP28
led = machine.Pin(28, machine.Pin.OUT) 
while True:
    print("blink!")
    led.on()
    time.sleep(0.2)
    led.off()
    time.sleep(0.2)

To use the on-board LED of the Pico W,

led = machine.Pin("LED", machine.Pin.OUT)

Detect button press

import machine, time

led = machine.Pin(28, machine.Pin.OUT)
# Using GP27 and 3.3V for button
button = machine.Pin(27, machine.Pin.IN, machine.Pin.PULL_DOWN)
print("Waiting...")
while True:
    if button.value():
        print("Button pressed")
        led.on()
        time.sleep(1)
        led.off()
    time.sleep(0.2)

Note: If you are connecting the button between a GPxx pin and ground, you will need to invert your button.value() check… ie if not button.value(): and set the pin built-in resistor to machine.Pin.PULL_UP.

import machine, time

led = machine.Pin("LED", machine.Pin.OUT)
# Using GP27 and GND for button
button = machine.Pin(27, machine.Pin.IN, machine.Pin.PULL_UP)
print("Waiting...")
while True:
    if not button.value():
        print("Button pressed")
        led.on()
        time.sleep(1)
        led.off()
    time.sleep(0.2)

9g servo

Download the Servo library file and save it to your board as servo.py.

import time
from machine import Pin,PWM
from servo import Servo

sg90_servo = Servo(pin=0) # Update for correct GPxx pin number
button = machine.Pin(2, machine.Pin.IN, Pin.PULL_UP) # Pin 2 and GND
while True:
    if not button.value():   # If button pressed
        print("Button press detected")
        # Servo operation
        sg90_servo.move(35)  # turns the servo to 0°.
        time.sleep(0.9)
        sg90_servo.move(90)  # turns the servo to 90°.
        time.sleep(1)
    time.sleep(0.2)

You will need to experiment with the values supplied to .move() as it varies from device to device.

Neopixels

Download the Neopixel library file and save it to your board as neopixel.py.

Rotating pattern across 8 LEDs

import time
from neopixel import Neopixel

# Number of LEDs, state library (use 0), GPIO pin, color scheme of LEDs
pixels = Neopixel(8, 0, 28, "GRB")

colors = [
    (255, 0, 0),    # Red
    (255, 127, 0),  # Orange
    (255, 255, 0),  # Yellow
    (0, 255, 0),    # Green
    (0, 0, 255),    # Blue
    (127, 0, 255),  # Violet
    (255, 0, 127),  # Pink
    (255, 255, 255) # White
]

while True:
    pixels.clear()
    # Set each LED to a color
    for i in range(len(colors)):
        print(f"Setting LED {i} to {colors[i]}")
        pixels[i] = colors[i]
        pixels.show()
        time.sleep(0.2)
    time.sleep(1)
    # Set each LED to off
    for i in range(len(colors)):
        print(f"Setting LED {i} to off")
        pixels[i] = (0,0,0)
        pixels.show()
        time.sleep(0.2)
    time.sleep(1)

Connect to WiFi

import network
import machine
import time

def connect_to_wifi(SSID, PASSWORD):
    led = machine.Pin("LED", machine.Pin.OUT)
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    led.on()
    if not wlan.isconnected():
        print('connecting to network...')
        wlan.connect(SSID, PASSWORD)
        while not wlan.isconnected():
            print('Waiting for Wi-Fi connection...')
            led.off()
            time.sleep(0.4)
            led.on()
            time.sleep(0.4)
    print('network config:', wlan.ifconfig())
    led.on()
    return wlan.ifconfig()[0]

ip = connect_to_wifi("SSID", "PASSWORD")

Obtain the current time

import time
import machine
import ntptime

# NTP Time Fetching Function
# Assumes WiFi connected device
def set_correct_time():
    while True:
        try:
            # Will set to UTC time
            ntptime.settime()
            break
        except:
            print("Waiting to set time...")
            time.sleep(5)
    # Update for timezone, Hong Kong local time being UTC+8
    rtc = machine.RTC()
    (year, month, day, weekday, hours, minutes, seconds, subseconds) = rtc.datetime()
    hours += 8
    if hours >= 24:
        hours -= 24 # Note: This doesn't change the day!
    # Set the RTC to the local time
    rtc.datetime((year, month, day, weekday, hours, minutes, seconds, subseconds))

set_correct_time()

Request data via HTTP/S

ntfy.sh is a handy little service for obtaining notifications to your mobile device from code. I find it very useful for having MicroProcessor projects use it to advise me of their IP address so I can interact with them.

import json
import machine
import urequests

def send_nfty_message(channel, message, link=None, server="https://ntfy.sh/"):
    print(f"[sending ntfy message] {server+channel} '{message}'")
    if link:
        response = urequests.post(url=server+channel, data=message, headers=[{"action":"view", "label":"Open", "url": link}])
    else:
        response = urequests.post(url=server+channel, data=message)        
    res = response.text
    print(f"[ntfy reply]",response.status_code,res)
    response.close()    
    return res

message = "My IoT device is at @ http://"+ip
send_nfty_message("your-ntfy-channel", message)

Simple web-server

I’ve written a simple web-server for the use of STC students. Download it and save as webserver.py.

There is also an associated stc library to contain commonly needed functions that it uses. Download the stc library and save as stc.py.

import network
import usocket as socket
from machine import Pin
import time
import json
import machine
import ntptime
import webserver # webserver.py
import stc # stc.py

# Constants
SSID = "SSID"  # Adjust as required
PASSWORD = "PASSWORD"  # Adjust as required
LED_PIN = 0  # Adjust as required

# Instantiate the LED pin
led = Pin(LED_PIN, Pin.OUT)

def callback(request):
    print("Received request",request)
    if request == "on":
        led.on()
    if request == "off":
        led.off()
    return

# Main function
def main():
    ip = webserver.connect_to_wifi(SSID, PASSWORD)
    stc.set_correct_time()
    stc.send_nfty_message("your-ntfy-channel", "My IoT lamp @ http://"+ip)
    webserver.start_server("0.0.0.0", 80, "index.html", callback)

# Run the program
if __name__ == '__main__':
    main()