Explore More - LED BLINK - AGTECH

1. Change the Blink code so that the LED blinks so fast that you cannot see it blinking. At what delay value does the LED change from visible blinking to not visible (to the human eye) blinking?  Remember, as long as you leave the structure of the code the same, you will be causing the light to turn on and off, with delays between the commands.
    
2. Change the Blink code so that the LED blinks “SOS” in Morse code. SOS is the international symbol for help. The SOS pattern is three short blinks (S) followed by three longer blinks (O) followed by three short blinks (S).

At the Thinkabit Lab, we engage students in a challenge that allows them to explore how the rate of blinking changes based on the delay value that is used, as follows:

Teacher says:  “Ladies and gentlemen, did you know that all of the lights in the room are blinking?  The lights in the ceiling, on the TV screens, on your computer screens, they’re all blinking.  

1. Explain: The challenge is for you to change the delays in your code so that your LED blinks so fast that you can no longer see it blink. However, I want you to find the threshold value because there are several values that will work.
    
2. Define the term threshold: The threshold is the largest delay value that you can use in both delays where you cannot see the light blink.
    
3. Explain: Let’s say the threshold value was 50. At a delay of 50, the light would look solid, but at 51 it would flutter a lit bit and you would be able to tell that it is blinking.
   • If you upload your code and you can see the light blinking, you need to choose a smaller value.
   • If you cannot see it blinking, then try a larger value to test if you’ve found the largest possible value.  
   • The answer is greater than 1 and less than 30 and it is the same number in both the delays and it’s a whole number. 
   • We encourage students not say their answer out loud, so that everyone has a chance to find the threshold value on their own.
4. The correct answer is typically a delay of 10, however sometimes 11 and 12 look solid as well.

If you are using the Thinkabit Lab Notebook:
 

Have students write their answer on page 14 for the question: “At what delay value could you no longer see the light blinking?”

“error compiling”

1. Click ‘upload’ again.

“problem uploading to board”

1. Be sure the port is connected to the right COM#
2. Unplug and re-plug the USB cable (possibly using a different USB port if another one is available).
3. Disconnect all wires from the Arduino board, unplug and re- plug the USB cable, close all Arduino windows and open the Blink code again, then try uploading again.

“expected ‘ ) ‘ before ‘;’ token”

1. Notice that it highlights the area that has a problem.
2. Here, it identifies that you’re missing a parenthesis somewhere. make sure every parenthesis has its match.

“expected ‘;’ before ‘delay’ ”

1. Notice it highlights the area the problem is in.
2. You’re missing a ‘;’ after a line of code. Check each line has a ‘;’ after it.