from microbit import *

import music

# A lookup table of morse codes and associated characters.

MORSE_CODE_LOOKUP = {

}

def decode(buffer):

# Attempts to get the buffer of Morse code data from the lookup table. If

# it's not there, just return a full stop.

return MORSE_CODE_LOOKUP.get(buffer, '.')

# How to display a single dot.

DOT = Image("00000:"

"00000:")

# How to display a single dash.

DASH = Image("00000:"

"00000:")

# To create a DOT you need to hold the button for less than 250ms.

DOT_THRESHOLD = 250

# To create a DASH you need to hold the button for less than 500ms.

DASH_THRESHOLD = 500

# Holds the incoming Morse characters.

buffer = ''

# Holds the translated Morse as normal text.

message = ''

# The time from which the device has been waiting for the next keypress.

started_to_wait = running_time()

# Put the device in a loop to wait for and react to key presses.

while True:

# Work out how long the device has been waiting for a keypress.

waiting = running_time() - started_to_wait

# Reset the timestamp for the key_down_time.

key_down_time = None

# If button_a is held down, then...

while button_a.is_pressed():

# Play a beep - this is Morse code y'know ;-)

music.pitch(880, 10)

# ...and if there's not a key_down_time then set it to now!

if not key_down_time:

key_down_time = running_time()

# Get the current time and call it key_up_time.

key_up_time = running_time()

# If there's a key_down_time (created when button_a was first pressed

# down).

if key_down_time:

# ... then work out for how long it was pressed.

duration = key_up_time - key_down_time

# If the duration is less than the max length for a "dot" press...

if duration < DOT_THRESHOLD:

# ... then add a dot to the BUFFER containing incoming Morse codes

# and display a dot on the display.

buffer += '.'

display.show(DOT)

# Else, if the duration is less than the max length for a "dash"

# press... (but longer than that for a DOT ~ handled above)

elif duration < DASH_THRESHOLD:

# ... then add a dash to the BUFFER and display a dash.

buffer += '-'

display.show(DASH)

# Otherwise, any other sort of keypress duration is ignored (this isn't

# needed, but added for "understandability").

else:

pass

# The button press has been handled, so reset the time from which the

# device is starting to wait for a button press.

started_to_wait = running_time()

# Otherwise, there hasn't been a button_a press during this cycle of the

# loop, so # check there's not been a pause to indicate an end of the

# incoming Morse code character. The pause must be longer than a DASH

# code's duration.

elif len(buffer) > 0 and waiting > DASH_THRESHOLD:

# There is a buffer and it's reached the end of a code so...

display.clear()

# Decode the incoming buffer.

character = decode(buffer)

# Reset the buffer to empty.

buffer = ''

# Show the decoded character.

display.show(character)

# Add the character to the message.

message += character

# Finally, if button_b was pressed while all the above was going on...

if button_b.was_pressed():

# ... display the message,

display.scroll(message)

# then reset it to empty (ready for a new message).

message = ''