pxt-calliope/docs/projects/step-counter.md

# Step counter

![A @boardname@ attached on a foot](/static/mb/projects/step-counter.png)

This project turns the @boardname@ into a simple step counter. A step counter is also known as a pedometer. Each **shake** event increments a **counter** variable. The step count is displayed on the LEDs.

## ~ hint

If you built a watch in the [make](/projects/watch/make) portion of the of the [Watch](/projects/watch) project, you can use the code from this project with it too.

## ~

## A counter

To build a counter, we'll need a variable to store the number of steps.

```blocks
let step = 0
step = 0
```

## Detecting a step

Assuming you attach the @boardname@ to your foot or ankle, it will get shaken  when you take a step. We can use the ``||input:on shake||`` event to detect a step (it should notice a step most of the time). Let's add the code to increment ``step`` by `1` when the @boardname@ is shaken.

```blocks
let step = 0
input.onGesture(Gesture.Shake, function () {
    step += 1
})
step = 0
```

## How many steps so far?

We want to always see how many steps were counted. In a ``||basic:forever||`` loop, we add a ``||basic:show number||`` block to display the value of ``step``.

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

## Display lag

Did you notice there is a lag, or delay, in the display of steps? This is because the ``step`` value can change **while** the @boardname@ is displaying a number. To remove the lag, add ``||led:stop animation||`` after changing the value of ``step``.

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