pxt-calliope/docs/reference/input/compass-heading.md
Juri Wolf 5f7a8e5301
Updates for V4 (#197)
* update yotta defaults for 16kb devices

* refactor deprecated blocks

* updates for button events

* update button events

* update refference

* update docs

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2022-08-10 09:36:19 -07:00

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# Compass Heading
Find which direction on a compass the @boardname@ is facing.
The @boardname@ measures the **compass heading** from `0` to `359`
degrees with its **magnetometer** chip. Different numbers mean north,
east, south, and west.
```sig
input.compassHeading();
```
## Returns
* a [number](/types/number) from `0` to `359` degrees, which means the compass heading. If the compass isn't ready, it returns `-1003`.
## Example
This program finds the compass heading and stores it in the
`degrees` variable.
```blocks
let degrees = input.compassHeading()
```
## ~hint
When you run a program that uses this function in a browser, click and drag
the compass needle on the screen to change the compass heading.
## ~
## Example: compass
This program finds the compass heading and then shows a letter
that means whether the @boardname@ is facing north (N), south (S),
east (E), or west (W).
```blocks
let degrees = 0
basic.forever(() => {
degrees = input.compassHeading()
if (degrees < 45) {
basic.showIcon(IconNames.ArrowNorth)
} else if (degrees < 135) {
basic.showIcon(IconNames.ArrowEast)
} else if (degrees < 225) {
basic.showIcon(IconNames.ArrowSouth)
} else if (degrees < 315) {
basic.showIcon(IconNames.ArrowWest)
} else {
basic.showIcon(IconNames.ArrowNorth)
}
})
```
## Calibration
Every time you start to use the compass (for example, if you have just turned the @boardname@ on),
the @boardname@ will start a [calibrate compass](/reference/input/calibrate-compass)
(adjust itself).
The [calibration step](https://support.microbit.org/support/solutions/articles/19000008874-calibrating-the-micro-bit-compass)
will ask you to draw a fill pattern on the screen by tilting the @boardname@.
If you are calibrating or using the compass near metal, it might
confuse the @boardname@.
## ~ hint
Keep the calibration handy by running it when the user pressed **A+B**.
```block
input.onButtonEvent(Button.AB, input.buttonEventClick(), () => {
input.calibrateCompass();
})
```
## ~
## See also
[acceleration](/reference/input/acceleration), [calibrate compass](/reference/input/calibrate-compass)