67 lines
2.1 KiB
Markdown
67 lines
2.1 KiB
Markdown
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# wait For Event
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Stop running the current code and wait for an event.
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```sig
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control.waitForEvent(0, 0)
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```
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You might want your code to stop for a while until some event you're expecting happens.
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If you want your code to pause until a known event happens, use a ``||control:wait for event||`` block.
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A known event is something you identify that happens on the board or in your program.
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An event has both a source and a cause. The source is where the event comes from, like a sensor or
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some condition in your program. The cause is what made the event happen at the source.
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You assign numbers for your event sources and causes. These numbers are used by [``||control:raise event||``](/reference/control/raise-event) to announce to your program that an event just happened.
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As an example, you could make a timer that always causes an event every 100 milliseconds. The source
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number for the timer is `6` and the cause value is `1`. The program could wait for one of the time
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events like this:
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```blocks
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const myTimer = 6;
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const timerTimeout = 1;
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control.runInParallel(function() {
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while (true) {
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control.waitMicros(100000)
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control.raiseEvent(myTimer, timerTimeout)
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}
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})
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control.waitForEvent(myTimer, timerTimeout)
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```
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## Parameters
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* **id**: the identification [number](/types/number) (the source) of this event, such as: `10`.
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* **value**: a [number](/types/number) tells what the cause of the event is, like: `4`.
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## Example #example
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Make a timeout timer to signal every 2 seconds. Wait two times and write to the
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console each time.
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```blocks
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const myTimer = 6;
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const timerTimeout = 1;
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control.runInParallel(function() {
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while (true) {
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pause(2000)
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control.raiseEvent(myTimer, timerTimeout)
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}
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})
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control.waitForEvent(myTimer, timerTimeout)
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console.log("Timer timeout")
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control.waitForEvent(myTimer, timerTimeout)
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console.log("Timer timeout")
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```
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**This is an advanced API.** For more information, see the
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[@boardname@ runtime messageBus documentation](https://lancaster-university.github.io/microbit-docs/ubit/messageBus/).
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## See also #seealso
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[raise event](/reference/control/raise-event), [on event](/reference/control/on-event)
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