tutorial4.md

let step = 0
input.onGesture(Gesture.Shake, function () {
    step += 1
})
basic.forever(function () {
    basic.showNumber(step)
})

ProjectSMART Pedometer Tutorial -- Level 4

Learning about Control Flow

Step 1

What you created in the previous tutorial is shown on the screen. In this tutorial, we will give it on/off buttons.

Our new program will have two variables. So, first, create a second variable (you can name it on) that we will use to tell the program if the pedometer should be counting steps or not.

To create a variable, click on the icon with 4 red stripes, then press Make a Variable.

Step 2

We want button A to be the on button, and button B to be the off button. This way, we can turn on the pedometer by pressing button A. Then we can press button B to turn it off.

Drag two ||input:on button A pressed|| blocks to your workspace, and change one of the to ||input:on button B pressed||.

input.onButtonPressed(Button.A, function () {
})
input.onButtonPressed(Button.B, function () {
})

Step 3

To make button A the on button and button B the off button, we need to do the following:

1. When button A is pressed, set the ||variables:on|| variable to ||logic:true||.
2. When button B is pressed, set the ||variables:on|| variable to ||logic:false||.

Can you figure out how to do that?

Hint: ||logic:true|| and ||logic:false|| are both values that you can find in the ||logic:Logic|| drawer. You can set the value of ||variables:on|| by using ||variables:set on to||.

input.onButtonPressed(Button.A, function () {
    on = true
})
input.onButtonPressed(Button.B, function () {
    on = false
})

Step 4

Now, we can change the ||variables:on|| variable by pressing buttons A and B.

But they still aren't working as on/off buttons yet! You can test it by pressing button B and then pressing the white dot next to SHAKE. The number still increases!

That's because we didn't create a condition that uses the value of the ||variables:on|| variable. We'll do that next.

Step 5

Look in the logic drawer, and drag the ||logic:if true then|| block onto the screen and into the ||input:on shake|| block.

The ||variables:change step by 1|| should be inside the mouth of the if block. If it is not, move it there.

input.onGesture(Gesture.Shake, function () {
    if (true) {
        step += 1
    }
})

Step 6

Recall that the pointy thing between if and then is called a condition. The ||logic:if true then|| block executes the instructions in the mouth if the condition is true. Right now, because the condition is ||logic:true||, ||variables:change step by 1|| will always execute no matter what.

Step 7

You can create your own condition, and replace the ||logic:true|| in the ||logic:if true then|| block with condition. A condition can be any statement or variable that has value ||logic:true|| or ||logic:false||.

This way, ||variables:step|| will increase only when the condition is true, and ||variables:step|| will stay the same when the condition is false.

Can you figure out how to create the condition with your ||variables:on|| variable? Hint: Look in the ||logic:Logic|| for useful blocks.

input.onGesture(Gesture.Shake, function () {
    if (on==true) {
        step += 1
    }
})

Step 8

Look at the @boardname@ and try "shaking" it. Does the number increase? Press button A, and shake it again. Press button B, and shake it. Do you know what the program is doing?

Step 9

The @boardname@ is now a pedometer that you can turn on and off! You can now flash your code into your real @boardname@.

Press the |Download| on the bottom left of your screen. You should see the lights on your real @boardname@ flashing.

Remember to head back to the tutorial webpage, and complete the rest of the activity.