Event Scheduling
EmberZNet Stack API Reference

Macros

#define emberEventControlSetInactive (control)   do { (control).status = EMBER_EVENT_INACTIVE ; } while (0)
Sets this EmberEventControl as inactive (no pending event).
#define emberEventControlGetActive (control)   ((control).status != EMBER_EVENT_INACTIVE )
Returns true if the event is active, false otherwise.
#define emberEventControlSetActive (control)   do { emEventControlSetActive (&(control)); } while (0)
Sets this EmberEventControl to run at the next available opportunity.
#define EMBER_MAX_EVENT_CONTROL_DELAY_MS ( HALF_MAX_INT32U_VALUE - 1)
The maximum delay that may be passed to emberEventControlSetDelayMS .
#define emberEventControlSetDelayMS (control, delay)   do { emEventControlSetDelayMS (&(control), (delay)); } while (0)
Sets this EmberEventControl to run "delay" milliseconds in the future. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MS .
#define EMBER_MAX_EVENT_CONTROL_DELAY_QS ( EMBER_MAX_EVENT_CONTROL_DELAY_MS >> 8)
The maximum delay that may be passed to emberEventControlSetDelayQS .
#define emberEventControlSetDelayQS (control, delay)   do { emEventControlSetDelayMS (&(control), (delay) << 8); } while (0)
Sets this EmberEventControl to run "delay" quarter seconds in the future. The 'quarter seconds' are actually 256 milliseconds long. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_QS .
#define EMBER_MAX_EVENT_CONTROL_DELAY_MINUTES ( EMBER_MAX_EVENT_CONTROL_DELAY_MS >> 16)
The maximum delay that may be passed to emberEventControlSetDelayMinutes .
#define emberEventControlSetDelayMinutes (control, delay)   do { emEventControlSetDelayMS (&(control), (delay) << 16); } while (0)
Sets this EmberEventControl to run "delay" minutes in the future. The 'minutes' are actually 65536 (0x10000) milliseconds long. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MINUTES .
#define emberEventControlGetRemainingMS (control)   ( emEventControlGetRemainingMS (&(control)))
Returns The amount of milliseconds remaining before the event is scheduled to run. If the event is inactive, MAX_INT32U_VALUE is returned.
#define emberTaskEnableIdling (allow)   do { emTaskEnableIdling ((allow)); } while (0)
Call this to indicate that an application supports processor idling.
#define emberMarkTaskActive (taskid)   do { emMarkTaskActive ((taskid)); } while (0)
Indicates that a task has something to do, so the CPU should not be idled until emberMarkTaskIdle is next called on this task.

Functions

void emEventControlSetActive ( EmberEventControl *event)
Sets this EmberEventControl to run at the next available opportunity.
void emEventControlSetDelayMS ( EmberEventControl *event, uint32_t delay)
Sets this EmberEventControl to run "delay" milliseconds in the future. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MS .
uint32_t emEventControlGetRemainingMS ( EmberEventControl *event)
Returns The amount of milliseconds remaining before the event is scheduled to run. If the event is inactive, MAX_INT32U_VALUE is returned.
void emberRunEvents ( EmberEventData *events)
An application typically creates an array of events along with their handlers.
void emberRunTask ( EmberTaskId taskid)
If an application has initialized a task via emberTaskInit, it should call emberRunTask() instead of emberRunEvents() to run the events associated with that task.
uint32_t emberMsToNextEvent ( EmberEventData *events, uint32_t maxMs)
Returns the number of milliseconds before the next event is scheduled to expire, or maxMs if no event is scheduled to expire within that time. NOTE: If any events are modified within an interrupt, it must be called with interrupts disabled or from within an ATOMIC() block in order to guarantee the accuracy of this API.
uint32_t emberMsToNextEventExtended ( EmberEventData *events, uint32_t maxMs, uint8_t *returnIndex)
This function does the same as emberMsToNextEvent() with the following addition. If the returnIndex is non-NULL, it will set the value pointed to by the pointer to be equal to the index of the event that is ready to fire next. If no events are active, then it returns 0xFF.
uint32_t emberMsToNextStackEvent (void)
Returns the number of milliseconds before the next stack event is scheduled to expire.
EmberTaskId emberTaskInit ( EmberEventData *events)
Initializes a task to be used for managing events and processor idling state. Returns the EmberTaskId , which represents the newly created task.
bool emberMarkTaskIdle ( EmberTaskId taskid)
Indicates that a task has nothing to do (unless any events are pending) and that it would be safe to idle the CPU if all other tasks also have nothing to do. This API should always be called with interrupts disabled. It will forcibly re-enable interrupts before returning. Returns true if the processor was idled, false if idling was not permitted because some other task has something to do.
void emTaskEnableIdling (bool allow)
void emMarkTaskActive ( EmberTaskId taskid)

Detailed Description

These macros implement an event abstraction that allows the application to schedule code to run after some specified time interval. An event consists of a procedure to be called at some point in the future and a control object that determines when the procedure should be called. Events are also useful for when an ISR needs to initiate an action that should run outside of ISR context.

See event.h for source code.

Note that while not required, it is recommended that the event-handling procedure explicitly defines the recurrence of the next event, either by rescheduling it via some kind of emberEventControlSetDelayXX() call or by deactivating it via a call to emberEventControlSetInactive() . In cases where the handler does not explicitly reschedule or cancel the event, the default behavior of the event control system is to keep the event immediately active as if the handler function had called emberEventControlSetActive(someEvent) or emberEventControlSetDelayMS(someEvent, 0)

The base time units for events are ticks. Each tick is approximately equal to a millisecond, but the true duration depends on the platform. The duration of a tick is 1000 / ::MILLISECOND_TICKS_PER_SECOND, where 1000 is the number of milliseconds per second and ::MILLISECOND_TICKS_PER_SECOND is the platform-specific number of ticks per second. For example, ::MILLISECOND_TICKS_PER_SECOND on the EM357 SoC is 1024, so each tick is therefore 1000 / 1024 = ~0.98 milliseconds. Calling emberEventControlSetDelayMS(someEvent, 100) on the EM357 SoC will schedule the event for 100 ticks * (1000 milliseconds / 1024 ticks) = ~97.7 milliseconds. Note however that the accuracy of the base tick depends on the timer source. Further, the scheduled delay is the minimum delay. If emberRunEvents or emberRunTask are not called frequently enough, the actual delay may be longer than the scheduled delay.

Additionally, the APIs for quarter second and minute delays ( emberEventControlSetDelayQS and emberEventControlSetDelayMinutes ) use "binary" units. One quarter second is 256 ticks and one minute is 65536 ticks. Calling emberEventControlSetDelayMinutes(someEvent, 3) on the EM357 SoC will schedule the event for 3 minutes * (65536 ticks / minute) * (1000 milliseconds / 1024 ticks) = ~3.2 minutes. It is possible to avoid these binary units by using emberEventControlSetDelayMS and the various MILLISECOND_TICKS_PER_XXX multipliers. For example, calling emberEventControlSetDelayMS(someEvent, 3 * MILLISECOND_TICKS_PER_MINUTE) will delay for 3 minutes on any platform. Be aware of EMBER_MAX_EVENT_CONTROL_DELAY_MS when using this approach.

Following are some brief usage examples.

EmberEventControl delayEvent;
EmberEventControl signalEvent;
EmberEventControl periodicEvent;
void delayEventHandler( void )
{
&frasl;&frasl; Disable this event until its next use.
emberEventControlSetInactive (delayEvent);
}
void signalEventHandler( void )
{
&frasl;&frasl; Disable this event until its next use.
emberEventControlSetInactive (signalEvent);
&frasl;&frasl; Sometimes we need to do something 100 ms later.
if (somethingIsExpected)
emberEventControlSetDelayMS (delayEvent, 100);
}
void periodicEventHandler( void )
{
emberEventControlSetDelayQS (periodicEvent, 4);
}
void someIsr( void )
{
&frasl;&frasl; Set the signal event to run at the first opportunity.
emberEventControlSetActive (signalEvent);
}
&frasl;&frasl; Put the controls and handlers in an array to run in
&frasl;&frasl; this order.
EmberEventData events[] =
{
{ &delayEvent, delayEventHandler },
{ &signalEvent, signalEentHandler },
{ &periodicEvent, periodicEventHandler },
{ NULL , NULL } &frasl;&frasl; terminator
};
void main( void )
{
&frasl;&frasl; Cause the periodic event to occur once a second.
emberEventControlSetDelayQS (periodicEvent, 4);
while ( true ) {
emberRunEvents (events);
}
}

Macro Definition Documentation

#define EMBER_MAX_EVENT_CONTROL_DELAY_MINUTES   ( EMBER_MAX_EVENT_CONTROL_DELAY_MS >> 16)

The maximum delay that may be passed to emberEventControlSetDelayMinutes .

#define EMBER_MAX_EVENT_CONTROL_DELAY_MS   ( HALF_MAX_INT32U_VALUE - 1)

The maximum delay that may be passed to emberEventControlSetDelayMS .

#define EMBER_MAX_EVENT_CONTROL_DELAY_QS   ( EMBER_MAX_EVENT_CONTROL_DELAY_MS >> 8)

The maximum delay that may be passed to emberEventControlSetDelayQS .

#define emberEventControlGetActive ( control ) ((control).status != EMBER_EVENT_INACTIVE )

Returns true if the event is active, false otherwise.

#define emberEventControlGetRemainingMS ( control ) ( emEventControlGetRemainingMS (&(control)))

Returns The amount of milliseconds remaining before the event is scheduled to run. If the event is inactive, MAX_INT32U_VALUE is returned.

#define emberEventControlSetActive ( control ) do { emEventControlSetActive (&(control)); } while (0)

Sets this EmberEventControl to run at the next available opportunity.

#define emberEventControlSetDelayMinutes ( control,
delay
) do { emEventControlSetDelayMS (&(control), (delay) << 16); } while (0)

Sets this EmberEventControl to run "delay" minutes in the future. The 'minutes' are actually 65536 (0x10000) milliseconds long. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MINUTES .

#define emberEventControlSetDelayMS ( control,
delay
) do { emEventControlSetDelayMS (&(control), (delay)); } while (0)

Sets this EmberEventControl to run "delay" milliseconds in the future. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MS .

#define emberEventControlSetDelayQS ( control,
delay
) do { emEventControlSetDelayMS (&(control), (delay) << 8); } while (0)

Sets this EmberEventControl to run "delay" quarter seconds in the future. The 'quarter seconds' are actually 256 milliseconds long. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_QS .

#define emberEventControlSetInactive ( control ) do { (control).status = EMBER_EVENT_INACTIVE ; } while (0)

Sets this EmberEventControl as inactive (no pending event).

#define emberMarkTaskActive ( taskid ) do { emMarkTaskActive ((taskid)); } while (0)

Indicates that a task has something to do, so the CPU should not be idled until emberMarkTaskIdle is next called on this task.

#define emberTaskEnableIdling ( allow ) do { emTaskEnableIdling ((allow)); } while (0)

Call this to indicate that an application supports processor idling.

Function Documentation

bool emberMarkTaskIdle ( EmberTaskId taskid )

Indicates that a task has nothing to do (unless any events are pending) and that it would be safe to idle the CPU if all other tasks also have nothing to do. This API should always be called with interrupts disabled. It will forcibly re-enable interrupts before returning. Returns true if the processor was idled, false if idling was not permitted because some other task has something to do.

uint32_t emberMsToNextEvent ( EmberEventData * events,
uint32_t maxMs
)

Returns the number of milliseconds before the next event is scheduled to expire, or maxMs if no event is scheduled to expire within that time. NOTE: If any events are modified within an interrupt, it must be called with interrupts disabled or from within an ATOMIC() block in order to guarantee the accuracy of this API.

uint32_t emberMsToNextEventExtended ( EmberEventData * events,
uint32_t maxMs,
uint8_t * returnIndex
)

This function does the same as emberMsToNextEvent() with the following addition. If the returnIndex is non-NULL, it will set the value pointed to by the pointer to be equal to the index of the event that is ready to fire next. If no events are active, then it returns 0xFF.

uint32_t emberMsToNextStackEvent ( void )

Returns the number of milliseconds before the next stack event is scheduled to expire.

void emberRunEvents ( EmberEventData * events )

An application typically creates an array of events along with their handlers.

The main loop passes the array to emberRunEvents() in order to call the handlers of any events whose time has arrived.

void emberRunTask ( EmberTaskId taskid )

If an application has initialized a task via emberTaskInit, it should call emberRunTask() instead of emberRunEvents() to run the events associated with that task.

EmberTaskId emberTaskInit ( EmberEventData * events )

Initializes a task to be used for managing events and processor idling state. Returns the EmberTaskId , which represents the newly created task.

uint32_t emEventControlGetRemainingMS ( EmberEventControl * event )

Returns The amount of milliseconds remaining before the event is scheduled to run. If the event is inactive, MAX_INT32U_VALUE is returned.

void emEventControlSetActive ( EmberEventControl * event )

Sets this EmberEventControl to run at the next available opportunity.

void emEventControlSetDelayMS ( EmberEventControl * event,
uint32_t delay
)

Sets this EmberEventControl to run "delay" milliseconds in the future. NOTE: To avoid rollover errors in event calculation, the delay must be less than EMBER_MAX_EVENT_CONTROL_DELAY_MS .

void emMarkTaskActive ( EmberTaskId taskid )
void emTaskEnableIdling ( bool allow )