MicroPython

Micro:bit Tinker Kit Components

Getting Started

Pre-coding:

  • Get hold of a Micro:bit Tinker Kit
  • Download the Mu editor
  • Before each project, write “from microbit import * ”

LED

 

Let the LED be connected to pin0

Command Usage
pin0.read_digital() Check if LED is lighted or not
pin0.read_digital() = 0 # means LED is not lighted
pin0.read_digital() = 1 # means LED is lighted
pin0.write_digital(value) Turn LED on or off
pin0.write_digital(1) # lights LED
pin0.write_digital(0) # turns LED off

Example: Blink

Pin Layout

  • LED: Pin0
from microbit import *
import time

# pins 
LED_PIN = pin0

while True:
    LED_PIN.write_digital(1)  # turns on LED
    time.sleep(0.5)  # delays the next line of code for 0.5s 
    LED_PIN.write_digital(0)  # turns off LED
    time.sleep(0.5)  # delays the next line of code for 0.5s

For more about digital signals click here

Mini Servo

 

Additional Library: servo.py
(adapted from https://github.com/microbit-playground/microbit-servo-class)

Using Additional Libraries:

Option 1:

  1. Copy and paste the code in the file above at the top of your code

Option 2 (adapted from https://github.com/microbit-playground/microbit-servo-class):

  1. Download the file in the link above and save it to the /mu_code/ directory in the root of your home directory
  2. Flash your code that is using the servo to mu
  3. An error message will scroll across the screen about the lack of the servo module.
  4. Once it has finished, click the ‘files’ icon in mu and upload the servo.py file to your microbit.
  5. Press reset on your microbit. When the program runs again it will load the module.

To initiate the servo, write: “servo_name = Servo(pin0) # attach servo to pin0”

Command Usage
servo_name.write_angle(angle) Changes the angle position of the servo

Eg.
servo.write_angle(180) # turns the servo to the 180 position

Example: Sweep

Pin Layout

  • Mini Servo: Pin0
from microbit import *
from servo import Servo
import time

# pins
Servo_pin = pin0

# initiate servo 
servo = Servo(Servo_pin) 

servo.write_angle(0)  # restart servo position 

# main code
while True:
    servo.write_angle(180)  # changes servo position to 180
    time.sleep(1)  # delays the next line of code by 1s
    servo.write_angle(0)  # changes servo position back to 0
    time.sleep(1)  # delays the next line of code by 1s

OLED

 

Additional Library: oled.py

Using Additional Libraries: Copy and paste the code in the file above at the top of your code

Initiating the OLED: from oled import *

Command Usage
oled_add_text(x, y, text) Writes a string on the OLED screen
Eg
oled_add_text(0, 0, “Hello”) # prints Hello at the top left corner of the OLED screen
oled_clear_screen() Clears the OLED screen

Example: Hello World!

Pin Layout

  • OLED: i2c
# Adapted from https://github.com/fizban99/microbit_ssd1306

from microbit import i2c, Image

OLED_ADDR = 0x3c
oled_screen = bytearray('b\x40') + bytearray(512)

def oled_initialize():
    for c in ([0xae], [0xa4], [0xd5, 0xf0], [0xa8, 0x3f], [0xd3, 0x00], [0 | 0x0], [0x8d, 0x14], [0x20, 0x00], [0x21, 0, 127], [0x22, 0, 63], [0xa0 | 0x1], [0xc8], [0xda, 0x12], [0x81, 0xcf], [0xd9, 0xf1], [0xdb, 0x40], [0xa6], [0xd6, 1], [0xaf]):
        i2c.write(OLED_ADDR, b'\x00' + bytearray(c))

def oled_set_pos(col=0, page=0):
    i2c.write(OLED_ADDR, b'\x00' + bytearray([0xb0 | page]))
    c1, c2 = col * 2 & 0x0F, col >> 3
    i2c.write(OLED_ADDR, b'\x00' + bytearray([0x00 | c1]))
    i2c.write(OLED_ADDR, b'\x00' + bytearray([0x10 | c2]))

def oled_clear_screen(c=0):
    global oled_screen
    oled_set_pos()
    for i in range(1, 513):
        oled_screen[i] = 0
    oled_draw_screen()

def oled_draw_screen():
    global oled_screen
    oled_set_pos()
    i2c.write(OLED_ADDR, oled_screen)

def oled_add_text(x, y, text):
    global oled_screen
    for i in range(0, min(len(text), 12 - x)):
        for c in range(0, 5):
            col = 0
            for r in range(1, 6):
                p = Image(text[i]).get_pixel(c, r - 1)
                col = col | (1 << r) if (p != 0) else col
            ind = x * 10 + y * 128 + i * 10 + c * 2 + 1
            oled_screen[ind], oled_screen[ind + 1] = col, col
    oled_set_pos(x * 5, y)
    ind0 = x * 10 + y * 128 + 1
    i2c.write(OLED_ADDR, b'\x40' + oled_screen[ind0 : (ind+1)])

oled_initialize()
oled_clear_screen()

oled_add_text(0, 0, "Hello World!")

Passive Buzzer

 

Addition library: type: “import music” at the top of your code

Musical notations:

Adapted from https://microbit-micropython.readthedocs.io/en/latest/music.html

Structure (case insensitive): NOTE[octave][:duration]

Eg.

a4:1 # note A in octave 4 that lasts for 1 tick (an arbitrary duration set by a tempo setting function)

R:2 # R signifies a rest (ie silence) which in this case lasts for 2 ticks

Accidentals (sharps and flats):

Sharp – #

Flat – b (lower case)

Eg. a#4:1 # note A sharp in octave 4 that lasts for 1 tick

Note:

  • Octave and duration parameters carry over to the next note until re-specified.
  • The default octave = 4 and the default duration = 4

The octave definitions follow the table of note frequencies in the following link

Let the buzzer be connected to pin0

Command Usage
music.set_tempo(ticks=4, bpm=120) Sets the tempo, where ticks and bpm (beats per min) are integers.

The indicated number of ticks lasts for 1 beat and each beat is played at a certain frequency per minute (expressed in BPM)

Eg.
music.set_tempo() # resets the tempo to the default ticks=4 and bpm = 120
music.set_tempo(ticks=2) # sets the no. of ticks per beat to 2, bpm = 120
music.set_tempo(bpm=180) # changes the tempo with 4 ticks per beat
music.get_tempo() Obtain the current tempo as a tuple of integers – (ticks,bpm)
music.play(music, pin=microbit.pin0, wait=True, loop=False)

 Plays a tune.

The duration and octave values are reset to their defaults before the music is played.

music can be a string: must be a single note eg “a1:4”
music can be list of notes as well

You can overwrite the default music pin at pin0

If wait = True, the music will play to the end before the next line of code is executed

If loop = True, the music repeats until music.stop() is called or the blocking call is interrupted

The music module also contains built in melodies that can be played using the following structure:

Eg music.play(music.ODE)

More built in melodies can be found in the following link under Built in Melodies

music.pitch(frequency, duration=-1, pin=microbit.pin0, wait=True) Plays the pitch at the integer frequency in ms.

Only one pitch can be played at a time.

If wait = True, the pitch will play to the end before the next line of code is executed

If duration is negative, the pitch will play continuously until the blocking call is interrupted, a new frequency is set or music.stop() is called

music.stop(pin=microbit.pin0) Stops all the music playing on a given pin (default at pin0)
music.reset() Resets the following values

  • ticks = 4
  • bpm = 120
  • duration = 4
  • octave = 4

Example: Doorbell

Pin Layout

  • Passive buzzer : pin0
  • Crash sensor: pin1
from microbit import *
import music

# pins
Buzzer_pin = pin0
CrashSensor_pin = pin1

# set up crash sensor
CrashSensor_pin.set_pull(CrashSensor_pin.PULL_UP)

while True:
    # if crash sensor is pressed, play a note, if not stop the music 
    if CrashSensor_pin.read_digital() == 1:
        music.stop()
    else:
        music.play("c5:4")

PIR Sensor

Essentially a motion detector

 

Let the PIR sensor be connected to pin0

Command Usage
pin0.read_digital() Check if PIR sensor detects motion or not
pin0.read_digital = 0 # means no motion detected
pin0.read_digital = 1 # means motion detected

Example: Motion Alarm

Pin Layout

  • Passive buzzer: Pin0
  • PIR sensor: pin1
from microbit import *
import music 

# pins 
buzzer_pin= pin0
PIRSensor_pin = pin1

while True:
    # if motion is detected play a sound, if not stop the music 
    if PIRSensor_pin.read_digital() == 0:
        music.stop()
    else:
        music.play("c5:4", wait=False)

For more about digital signals click here

Crash Sensor

 

Note: always set the pull of the pin connected to the crash sensor to PULL_UP by writing:

“pin0.set_pull(pin0.PULL_UP) # connect the crash sensor to pin0”

To learn more about pull-up resistors, click here

Let the crash sensor be connected to pin0

Command Usage
pin0.read_digital() Check if crash sensor is pressed or not
pin0.read_digital = 0 #means crash sensor is pressed
pin0.read_digital = 1 #means crash sensor is not pressed

Example: LED switch

Pin Layout

  • Crash sensor: Pin0
  • LED: pin1
from microbit import *

# pins
CrashSensor_pin = pin0
LED_pin = pin1
 
# set up crash sensor
CrashSensor_pin.set_pull(CrashSensor_pin.PULL_UP)

# main code
while True:
    # if crash sensor is pressed, LED lights up 
    if CrashSensor_pin.read_digital() == 0: 
        LED_pin.write_digital(1)
    
    # if crash sensor is not pressed, LED does not light up
    else: 
        LED_pin.write_digital(0)

For more about digital signals click here

Soil Moisture Sensor

 

Let the soil moisture sensor be connected to pin0

Command Usage
pin0.read_analog() Gets the moisture level of the surroundings on a scale from 0 to 1023 (3.3V)

Example: Display soil moisture

Pin Layout

  • Soil Moisture Sensor: pin0 
from microbit import *
import time

# pins
soilMoistureSensor_pin = pin0

while True:
    soil_moisture = soilMoistureSensor_pin.read_analog()
    display.scroll(soil_moisture)
    time.sleep(1)

For more about analog signals click here

ADKeypad

 

About the ADKeypad:

The ADKeypad has 5 buttons labeled from A to E. When each button is pressed, they give unique analog signals.

By experimenting on our side, the buttons give the following range of signals.

  • A – 0 to 10
  • B – 45 to 55
  • C – 90 to 100
  • D – 135 to 140
  • E – 535 to 545

*disclaimer: your ADKeyboard might produce different results, do try to find out the values for yours

Let the ADKeypad be connected to pin0

Command Usage
pin0.read_analog() Gets the signal from the ADKeyboard ranging from 0 to 1023 (3.3V)

Example: Image Pop-up

Pin Layout

  • ADKeypad: pin0 
from microbit import *

# pins
ADKeypad_pin = pin0

while True:
    # buttonA
    if ADKeypad_pin.read_analog() > 0 and ADKeypad_pin.read_analog() < 10:
        display.show(Image.SILLY)

    # buttonB
    if ADKeypad_pin.read_analog() > 45 and ADKeypad_pin.read_analog() < 55:
        display.show(Image.HAPPY)

    # buttonC
    if ADKeypad_pin.read_analog() > 90 and ADKeypad_pin.read_analog() < 100:
        display.show(Image.SKULL)

    # buttonD
    if ADKeypad_pin.read_analog() > 135 and ADKeypad_pin.read_analog() < 140:
        display.show(Image.PITCHFORK)

    # buttonE
    if ADKeypad_pin.read_analog() > 535 and ADKeypad_pin.read_analog() < 545:
        display.show(Image.DUCK)

For more about analog signals click here

Potentiometer

 

Let the potentiometer be connected to pin0

Command Usage
pin0.read_analog() Get an indication of how much the knob is turned by, on a scale from 0 to 1023 (3.3V)

Example: Light Switch

Pin Layout

  • Potentiometer: pin0
  • Red LED : pin1
  • Green LED: pin2
  • Blue LED: pin8
from microbit import *

# pins
p_pin = pin0  # potentiometer_pin
redLED_pin = pin1
greenLED_pin = pin2
blueLED_pin = pin8

while True:
    # turn on red led only
    if p_pin.read_analog() > 0 and p_pin.read_analog() <= 341:
        redLED_pin.write_digital(1)
        greenLED_pin.write_digital(0)
        blueLED_pin.write_digital(0)

    # turn on green led only
    if p_pin.read_analog() > 341 and p_pin.read_analog() <= 682:
        redLED_pin.write_digital(0)
        greenLED_pin.write_digital(1)
        blueLED_pin.write_digital(0)

    # turn on blue led only
    if p_pin.read_analog() > 682 and p_pin.read_analog() <= 1023:
        redLED_pin.write_digital(0)
        greenLED_pin.write_digital(0)
        blueLED_pin.write_digital(1)

For more about analog signals click here

Find out more

For a more comprehensive explanation of MicroPython, visit the official documentation here!

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