Transmitter

class Servo:

    """
    A simple class for controlling hobby servos.
    Args:
        pin (pin0 .. pin3): The pin where servo is connected.
        freq (int): The frequency of the signal, in hertz.
        min_us (int): The minimum signal length supported by the servo.
        max_us (int): The maximum signal length supported by the servo.
        angle (int): The angle between minimum and maximum positions.
    Usage:
        SG90 @ 3.3v servo connected to pin0
        = Servo(pin0).write_angle(90)
    """

    def __init__(self, pin, freq=50, min_us=600, max_us=2400, angle=180):
        self.min_us = min_us
        self.max_us = max_us
        self.us = 0
        self.freq = freq
        self.angle = angle
        self.analog_period = 0
        self.pin = pin
        analog_period = round((1/self.freq) * 1000)  # hertz to miliseconds
        self.pin.set_analog_period(analog_period)

    def write_us(self, us):
        us = min(self.max_us, max(self.min_us, us))
        duty = round(us * 1024 * self.freq // 1000000)
        self.pin.write_analog(duty)
        self.pin.write_digital(0)  # turn the pin off

    def write_angle(self, degrees=None):
        degrees = degrees % 360
        total_range = self.max_us - self.min_us
        us = self.min_us + total_range * degrees // self.angle
        self.write_us(us)

from microbit import *

MORSE_CODE =  {'A': '.-',     'B': '-...',   'C': '-.-.',
    'D': '-..',    'E': '.',      'F': '..-.',
    'G': '--.',    'H': '....',   'I': '..',
    'J': '.---',   'K': '-.-',    'L': '.-..',
    'M': '--',     'N': '-.',     'O': '---',
    'P': '.--.',   'Q': '--.-',   'R': '.-.',
    'S': '...',    'T': '-',      'U': '..-',
    'V': '...-',   'W': '.--',    'X': '-..-',
    'Y': '-.--',   'Z': '--..',
    '0': '-----',  '1': '.----',  '2': '..---',
    '3': '...--',  '4': '....-',  '5': '.....',
    '6': '-....',  '7': '--...',  '8': '---..',
    '9': '----.' }

message_to_send = "HELLO WORLD" #insert your own message here
encoded_message = "".join([MORSE_CODE[letter] + ' ' for letter in message_to_send])

press_angle = 150
release_angle = 60

Servo(pin0).write_angle(release_angle)

for char in encoded_message: #repeat for each character in the encoded message
    display.show(char, wait=False)
    if char == '.':
        Servo(pin0).write_angle(press_angle) #tug on the string for 0.6s
        sleep(600)
    elif char == '-':
        Servo(pin0).write_angle(press_angle)
        sleep(1200)
    else:
        Servo(pin0).write_angle(press_angle)
        sleep(2000)
    Servo(pin0).write_angle(release_angle) #release the string for 1s
    sleep(1000)