S.O.S. Blinking LED

Now that you can make an LED blink simply, try this challenge. (modified from this tutorial)

Morse Code

Morse code is a system for sending messages as a sequence of ON and OFF signals with predefined spaces in between.

A key for international Morse code Attribution: Rhey T. Snodgrass & Victor F. Camp, 1922, Public domain, via Wikimedia Commons

Characters in Morse code are represented by a series of dots and dashes, which we will use to determine the length of time our LED turns on for.

• 1 dot = turning the LED on for 1 unit of time, then off again
• 1 dash = turning the LED on for 3 units of time, then off again
• Between letters, we wait for 3 units.
• Between words, we wait for 7 units.

Your Challenge

Write code inside your “while True” loop to blink the message SOS. We need to make our LED:

1. blink 3 dots (S)
2. wait for 3 units (between letters)
3. blink 3 dashes (O)
4. wait for 3 units (between letters)
5. blink 3 dots (S)
6. wait for 7 units (between words)

tips:

• Unit time: As long as your units are consistent, the code is the same. For example:

Option #1

UNIT = 1.0
# unit time of 1s each. This is a LONG processing code
UNIT = 0.2
# unit time of 0.1s each. This is a MUCH FASTER processing code.

#Dot
led.value = True # turn on
time.sleep(UNIT) # sleep 3 "units"
led.value = False # turn off
time.sleep(UNIT)

#Dash
led.value = True # turn on
time.sleep(UNIT*3) # sleep 3 "units"
led.value = False # turn off
time.sleep(UNIT)

Extension

Now that you can S.0.S, try out other words to send!

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