---
title: wakeAtTime(AbsoluteTime)
framework: kernel
role: pseudoSymbol
path: kernel/iotimereventsource/1809684-wakeattime
---

# wakeAtTime(AbsoluteTime)

Setup a callback at this absolute time.

## Declaration

```occ
virtual IOReturn wakeAtTime(
 AbsoluteTimeabstime); 
```

## Parameters

- `abstime`: Absolute Time when to wake up, counted in 'decrementer' units and starts at zero when system boots.

## Return Value

Return Value kIOReturnSuccess if everything is fine, kIOReturnNoResources if action hasn't been declared by init or IOEventSource::setAction (qqv).

## Overview

Overview Starts the timer, which will expire at abstime. After it expires, the timer will call the 'action' registered in the init() function. This timer is not periodic, a further call is needed to reset and restart the timer after it expires.

## See Also

### Miscellaneous

- [cancelTimeout](kernel/iotimereventsource/1809565-canceltimeout.md)
- [disable](kernel/iotimereventsource/1809571-disable.md)
- [enable](kernel/iotimereventsource/1809577-enable.md)
- [free](kernel/iotimereventsource/1809588-free.md)
- [init](kernel/iotimereventsource/1809597-init.md)
- [setTimeout(AbsoluteTime)](kernel/iotimereventsource/1809607-settimeout.md)
- [setTimeout(UInt32, UInt32)](kernel/iotimereventsource/1809617-settimeout.md)
- [setTimeoutFunc](kernel/iotimereventsource/1809624-settimeoutfunc.md)
- [setTimeoutMS](kernel/iotimereventsource/1809629-settimeoutms.md)
- [setTimeoutTicks](kernel/iotimereventsource/1809639-settimeoutticks.md)
- [setTimeoutUS](kernel/iotimereventsource/1809649-settimeoutus.md)
- [timeout](kernel/iotimereventsource/1809663-timeout.md)
- [timerEventSource](kernel/iotimereventsource/1809672-timereventsource.md)
- [wakeAtTime(UInt32, UInt32)](kernel/iotimereventsource/1809694-wakeattime.md)
- [wakeAtTimeMS](kernel/iotimereventsource/1809708-wakeattimems.md)
- [wakeAtTimeTicks](kernel/iotimereventsource/1809720-wakeattimeticks.md)
- [wakeAtTimeUS](kernel/iotimereventsource/1809737-wakeattimeus.md)