Variables and Logic Blocks

Variables

• What is a variable?
  • A variable is used to store information inside a computer program.
  • These variables have descriptive names and can later be referenced within the program to retrieve the information they store.
• What are some examples of variables?
  • Weather = sunny
  • Light = red
  • The variable names weather and light reference the stored values.
• What are variables in daily life?
  • Something that changes like the weather, the time, someone is standing or sitting?
  • Volume on headphones

Example (live intro by instructor)

https://makecode.com/_Jj17e3CiEetw

Variables Example

• This is an example of how to create a variable called “exampleVariable”
• Click on the variables tab and select “Make a variable”
• After that you can select to “set” the variable to a value.
• Drag the exampleVariable onto the “set pixel color” function.

Variables Exercise #1

• For this exercise attempt to make the led light at position “0” blink red continuously.
• Use a forever loop to make the light blink forever.
• Create a variable called “led” and set it to the value of “0”.
• Make the pixel color of “led” red
• Make the program pause.
• Next, make the pixel color of “led” black
• Make the program pause again.

Variables Exercise #1 - Solution

Variables Exercise #2

• In the previous exercise, we made LED light 0 blink.
• For this exercise perform the following:
• Use a forever loop to make all of the activity below happen forever
• Attempt to make led light 0 blink red
• Make a sound play on the CPX chip
• Pause for 500 ms
• Next make led light 1 blink
• Pause for 500 ms
• Make a sound play on the CPX chip

Variables Exercise #2 - Solution

Logic Blocks

• What are logic blocks?
  • Logic blocks are essentially a block of code. The commands inside that block of code will only run under certain conditions.
• What are examples of logic blocks?
  • An example of a logic block would be an “If…then” statement.
  • “If the weather is below 50 degrees then put on a jacket”
• What are logic in daily life?
  • Something that requires making decisions.
  • IF the traffic light is GREEN, then go
  • ELSE IF the traffic light is YELLOW then slow down
  • ELSE stop

Logic Block Example

• This is an example of a logic block.
• In the example on the left the code inside the “else” statement will run because the condition of “does exampleVariable = 1” is not met.
• In the example on the right the code inside of the “if” statement is run because the value of “exampleVariable” does equal 1.

Logic Block Exercise #1

• For this exercise we will set a value to a variable and then perform different actions in an “if…else” statement depending on the value of that variable.
  • Create a variable named ” lightonoff “.
  • Set the ” lightonoff ” variable to the value “0”
  • Create an “if……else” statement
  • For the “If……else” statement set the criteria so that if the value of ” lightonoff ” is equal to “0” then the pixel color at “0” will be black.
  • If the value of ” lightonoff ” does not equal “0” then make the led light 0 blink red and white.
  • In order to make the led light number 0 blink red/white you will need to set the pixel color to red, then pause, and then set it to white, and then pause.
• Questions:
  • Why does the program do nothing when we set the value of ” lightonoff ” to “0”?
  • What happens if you change the value of ” lightonoff ” to “1”?

Logic Blocks Exercise #1 - Solution

Logic Block Exercise #2

• In the previous exercise, we had to change the value of the “lightonoff” variable to turn on or turn off the light. Extend the example to do the following:
  • On click of Button A, turn on the light.
  • On click of Button B, turn off the light.
  • By doing this, you not have to change the value of the variable manually.
  • Also, you will implement a functionality resembling a light switch in your home.
• Button A and Button B can be located on the CPX device as highlighted below: