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/*
FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License (version 2) as published by the
Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: http://www.freertos.org/a00114.html and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
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license and Real Time Engineers Ltd. contact details.
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including FreeRTOS+Trace - an indispensable productivity tool, and our new
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http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
*/
#ifndef TIMERS_H
#define TIMERS_H
#ifndef INC_FREERTOS_H
#error "include FreeRTOS.h must appear in source files before include timers.h"
#endif
#include "portable.h"
#include "list.h"
#include "task.h"
#ifdef __cplusplus
extern "C" {
#endif
/* IDs for commands that can be sent/received on the timer queue. These are to
be used solely through the macros that make up the public software timer API,
as defined below. */
#define tmrCOMMAND_START 0
#define tmrCOMMAND_STOP 1
#define tmrCOMMAND_CHANGE_PERIOD 2
#define tmrCOMMAND_DELETE 3
/*-----------------------------------------------------------
* MACROS AND DEFINITIONS
*----------------------------------------------------------*/
/**
* Type by which software timers are referenced. For example, a call to
* xTimerCreate() returns an xTimerHandle variable that can then be used to
* reference the subject timer in calls to other software timer API functions
* (for example, xTimerStart(), xTimerReset(), etc.).
*/
typedef void * xTimerHandle;
/* Define the prototype to which timer callback functions must conform. */
typedef void (*tmrTIMER_CALLBACK)( xTimerHandle xTimer );
/**
* xTimerHandle xTimerCreate( const signed char *pcTimerName,
* portTickType xTimerPeriodInTicks,
* unsigned portBASE_TYPE uxAutoReload,
* void * pvTimerID,
* tmrTIMER_CALLBACK pxCallbackFunction );
*
* Creates a new software timer instance. This allocates the storage required
* by the new timer, initialises the new timers internal state, and returns a
* handle by which the new timer can be referenced.
*
* Timers are created in the dormant state. The xTimerStart(), xTimerReset(),
* xTimerStartFromISR(), xTimerResetFromISR(), xTimerChangePeriod() and
* xTimerChangePeriodFromISR() API functions can all be used to transition a timer into the
* active state.
*
* @param pcTimerName A text name that is assigned to the timer. This is done
* purely to assist debugging. The kernel itself only ever references a timer by
* its handle, and never by its name.
*
* @param xTimerPeriodInTicks The timer period. The time is defined in tick periods so
* the constant portTICK_RATE_MS can be used to convert a time that has been
* specified in milliseconds. For example, if the timer must expire after 100
* ticks, then xTimerPeriodInTicks should be set to 100. Alternatively, if the timer
* must expire after 500ms, then xPeriod can be set to ( 500 / portTICK_RATE_MS )
* provided configTICK_RATE_HZ is less than or equal to 1000.
*
* @param uxAutoReload If uxAutoReload is set to pdTRUE then the timer will
* expire repeatedly with a frequency set by the xTimerPeriodInTicks parameter. If
* uxAutoReload is set to pdFALSE then the timer will be a one-shot timer and
* enter the dormant state after it expires.
*
* @param pvTimerID An identifier that is assigned to the timer being created.
* Typically this would be used in the timer callback function to identify which
* timer expired when the same callback function is assigned to more than one
* timer.
*
* @param pxCallbackFunction The function to call when the timer expires.
* Callback functions must have the prototype defined by tmrTIMER_CALLBACK,
* which is "void vCallbackFunction( xTimerHandle xTimer );".
*
* @return If the timer is successfully create then a handle to the newly
* created timer is returned. If the timer cannot be created (because either
* there is insufficient FreeRTOS heap remaining to allocate the timer
* structures, or the timer period was set to 0) then 0 is returned.
*
* Example usage:
*
* #define NUM_TIMERS 5
*
* // An array to hold handles to the created timers.
* xTimerHandle xTimers[ NUM_TIMERS ];
*
* // An array to hold a count of the number of times each timer expires.
* long lExpireCounters[ NUM_TIMERS ] = { 0 };
*
* // Define a callback function that will be used by multiple timer instances.
* // The callback function does nothing but count the number of times the
* // associated timer expires, and stop the timer once the timer has expired
* // 10 times.
* void vTimerCallback( xTimerHandle pxTimer )
* {
* long lArrayIndex;
* const long xMaxExpiryCountBeforeStopping = 10;
*
* // Optionally do something if the pxTimer parameter is NULL.
* configASSERT( pxTimer );
*
* // Which timer expired?
* lArrayIndex = ( long ) pvTimerGetTimerID( pxTimer );
*
* // Increment the number of times that pxTimer has expired.
* lExpireCounters[ lArrayIndex ] += 1;
*
* // If the timer has expired 10 times then stop it from running.
* if( lExpireCounters[ lArrayIndex ] == xMaxExpiryCountBeforeStopping )
* {
* // Do not use a block time if calling a timer API function from a
* // timer callback function, as doing so could cause a deadlock!
* xTimerStop( pxTimer, 0 );
* }
* }
*
* void main( void )
* {
* long x;
*
* // Create then start some timers. Starting the timers before the scheduler
* // has been started means the timers will start running immediately that
* // the scheduler starts.
* for( x = 0; x < NUM_TIMERS; x++ )
* {
* xTimers[ x ] = xTimerCreate( "Timer", // Just a text name, not used by the kernel.
* ( 100 * x ), // The timer period in ticks.
* pdTRUE, // The timers will auto-reload themselves when they expire.
* ( void * ) x, // Assign each timer a unique id equal to its array index.
* vTimerCallback // Each timer calls the same callback when it expires.
* );
*
* if( xTimers[ x ] == NULL )
* {
* // The timer was not created.
* }
* else
* {
* // Start the timer. No block time is specified, and even if one was
* // it would be ignored because the scheduler has not yet been
* // started.
* if( xTimerStart( xTimers[ x ], 0 ) != pdPASS )
* {
* // The timer could not be set into the Active state.
* }
* }
* }
*
* // ...
* // Create tasks here.
* // ...
*
* // Starting the scheduler will start the timers running as they have already
* // been set into the active state.
* xTaskStartScheduler();
*
* // Should not reach here.
* for( ;; );
* }
*/
xTimerHandle xTimerCreate( const signed char * const pcTimerName, portTickType xTimerPeriodInTicks, unsigned portBASE_TYPE uxAutoReload, void * pvTimerID, tmrTIMER_CALLBACK pxCallbackFunction ) PRIVILEGED_FUNCTION;
/**
* void *pvTimerGetTimerID( xTimerHandle xTimer );
*
* Returns the ID assigned to the timer.
*
* IDs are assigned to timers using the pvTimerID parameter of the call to
* xTimerCreated() that was used to create the timer.
*
* If the same callback function is assigned to multiple timers then the timer
* ID can be used within the callback function to identify which timer actually
* expired.
*
* @param xTimer The timer being queried.
*
* @return The ID assigned to the timer being queried.
*
* Example usage:
*
* See the xTimerCreate() API function example usage scenario.
*/
void *pvTimerGetTimerID( xTimerHandle xTimer ) PRIVILEGED_FUNCTION;
/**
* portBASE_TYPE xTimerIsTimerActive( xTimerHandle xTimer );
*
* Queries a timer to see if it is active or dormant.
*
* A timer will be dormant if:
* 1) It has been created but not started, or
* 2) It is an expired on-shot timer that has not been restarted.
*
* Timers are created in the dormant state. The xTimerStart(), xTimerReset(),
* xTimerStartFromISR(), xTimerResetFromISR(), xTimerChangePeriod() and
* xTimerChangePeriodFromISR() API functions can all be used to transition a timer into the
* active state.
*
* @param xTimer The timer being queried.
*
* @return pdFALSE will be returned if the timer is dormant. A value other than
* pdFALSE will be returned if the timer is active.
*
* Example usage:
*
* // This function assumes xTimer has already been created.
* void vAFunction( xTimerHandle xTimer )
* {
* if( xTimerIsTimerActive( xTimer ) != pdFALSE ) // or more simply and equivalently "if( xTimerIsTimerActive( xTimer ) )"
* {
* // xTimer is active, do something.
* }
* else
* {
* // xTimer is not active, do something else.
* }
* }
*/
portBASE_TYPE xTimerIsTimerActive( xTimerHandle xTimer ) PRIVILEGED_FUNCTION;
/**
* xTimerGetTimerDaemonTaskHandle() is only available if
* INCLUDE_xTimerGetTimerDaemonTaskHandle is set to 1 in FreeRTOSConfig.h.
*
* Simply returns the handle of the timer service/daemon task. It it not valid
* to call xTimerGetTimerDaemonTaskHandle() before the scheduler has been started.
*/
xTaskHandle xTimerGetTimerDaemonTaskHandle( void );
/**
* portBASE_TYPE xTimerStart( xTimerHandle xTimer, portTickType xBlockTime );
*
* Timer functionality is provided by a timer service/daemon task. Many of the
* public FreeRTOS timer API functions send commands to the timer service task
* though a queue called the timer command queue. The timer command queue is
* private to the kernel itself and is not directly accessible to application
* code. The length of the timer command queue is set by the
* configTIMER_QUEUE_LENGTH configuration constant.
*
* xTimerStart() starts a timer that was previously created using the
* xTimerCreate() API function. If the timer had already been started and was
* already in the active state, then xTimerStart() has equivalent functionality
* to the xTimerReset() API function.
*
* Starting a timer ensures the timer is in the active state. If the timer
* is not stopped, deleted, or reset in the mean time, the callback function
* associated with the timer will get called 'n' ticks after xTimerStart() was
* called, where 'n' is the timers defined period.
*
* It is valid to call xTimerStart() before the scheduler has been started, but
* when this is done the timer will not actually start until the scheduler is
* started, and the timers expiry time will be relative to when the scheduler is
* started, not relative to when xTimerStart() was called.
*
* The configUSE_TIMERS configuration constant must be set to 1 for xTimerStart()
* to be available.
*
* @param xTimer The handle of the timer being started/restarted.
*
* @param xBlockTime Specifies the time, in ticks, that the calling task should
* be held in the Blocked state to wait for the start command to be successfully
* sent to the timer command queue, should the queue already be full when
* xTimerStart() was called. xBlockTime is ignored if xTimerStart() is called
* before the scheduler is started.
*
* @return pdFAIL will be returned if the start command could not be sent to
* the timer command queue even after xBlockTime ticks had passed. pdPASS will
* be returned if the command was successfully sent to the timer command queue.
* When the command is actually processed will depend on the priority of the
* timer service/daemon task relative to other tasks in the system, although the
* timers expiry time is relative to when xTimerStart() is actually called. The
* timer service/daemon task priority is set by the configTIMER_TASK_PRIORITY
* configuration constant.
*
* Example usage:
*
* See the xTimerCreate() API function example usage scenario.
*
*/
#define xTimerStart( xTimer, xBlockTime ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_START, ( xTaskGetTickCount() ), NULL, ( xBlockTime ) )
/**
* portBASE_TYPE xTimerStop( xTimerHandle xTimer, portTickType xBlockTime );
*
* Timer functionality is provided by a timer service/daemon task. Many of the
* public FreeRTOS timer API functions send commands to the timer service task
* though a queue called the timer command queue. The timer command queue is
* private to the kernel itself and is not directly accessible to application
* code. The length of the timer command queue is set by the
* configTIMER_QUEUE_LENGTH configuration constant.
*
* xTimerStop() stops a timer that was previously started using either of the
* The xTimerStart(), xTimerReset(), xTimerStartFromISR(), xTimerResetFromISR(),
* xTimerChangePeriod() or xTimerChangePeriodFromISR() API functions.
*
* Stopping a timer ensures the timer is not in the active state.
*
* The configUSE_TIMERS configuration constant must be set to 1 for xTimerStop()
* to be available.
*
* @param xTimer The handle of the timer being stopped.
*
* @param xBlockTime Specifies the time, in ticks, that the calling task should
* be held in the Blocked state to wait for the stop command to be successfully
* sent to the timer command queue, should the queue already be full when
* xTimerStop() was called. xBlockTime is ignored if xTimerStop() is called
* before the scheduler is started.
*
* @return pdFAIL will be returned if the stop command could not be sent to
* the timer command queue even after xBlockTime ticks had passed. pdPASS will
* be returned if the command was successfully sent to the timer command queue.
* When the command is actually processed will depend on the priority of the
* timer service/daemon task relative to other tasks in the system. The timer
* service/daemon task priority is set by the configTIMER_TASK_PRIORITY
* configuration constant.
*
* Example usage:
*
* See the xTimerCreate() API function example usage scenario.
*
*/
#define xTimerStop( xTimer, xBlockTime ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_STOP, 0U, NULL, ( xBlockTime ) )
/**
* portBASE_TYPE xTimerChangePeriod( xTimerHandle xTimer,
* portTickType xNewPeriod,
* portTickType xBlockTime );
*
* Timer functionality is provided by a timer service/daemon task. Many of the
* public FreeRTOS timer API functions send commands to the timer service task
* though a queue called the timer command queue. The timer command queue is
* private to the kernel itself and is not directly accessible to application
* code. The length of the timer command queue is set by the
* configTIMER_QUEUE_LENGTH configuration constant.
*
* xTimerChangePeriod() changes the period of a timer that was previously
* created using the xTimerCreate() API function.
*
* xTimerChangePeriod() can be called to change the period of an active or
* dormant state timer.
*
* The configUSE_TIMERS configuration constant must be set to 1 for
* xTimerChangePeriod() to be available.
*
* @param xTimer The handle of the timer that is having its period changed.
*
* @param xNewPeriod The new period for xTimer. Timer periods are specified in
* tick periods, so the constant portTICK_RATE_MS can be used to convert a time
* that has been specified in milliseconds. For example, if the timer must
* expire after 100 ticks, then xNewPeriod should be set to 100. Alternatively,
* if the timer must expire after 500ms, then xNewPeriod can be set to
* ( 500 / portTICK_RATE_MS ) provided configTICK_RATE_HZ is less than
* or equal to 1000.
*
* @param xBlockTime Specifies the time, in ticks, that the calling task should
* be held in the Blocked state to wait for the change period command to be
* successfully sent to the timer command queue, should the queue already be
* full when xTimerChangePeriod() was called. xBlockTime is ignored if
* xTimerChangePeriod() is called before the scheduler is started.
*
* @return pdFAIL will be returned if the change period command could not be
* sent to the timer command queue even after xBlockTime ticks had passed.
* pdPASS will be returned if the command was successfully sent to the timer
* command queue. When the command is actually processed will depend on the
* priority of the timer service/daemon task relative to other tasks in the
* system. The timer service/daemon task priority is set by the
* configTIMER_TASK_PRIORITY configuration constant.
*
* Example usage:
*
* // This function assumes xTimer has already been created. If the timer
* // referenced by xTimer is already active when it is called, then the timer
* // is deleted. If the timer referenced by xTimer is not active when it is
* // called, then the period of the timer is set to 500ms and the timer is
* // started.
* void vAFunction( xTimerHandle xTimer )
* {
* if( xTimerIsTimerActive( xTimer ) != pdFALSE ) // or more simply and equivalently "if( xTimerIsTimerActive( xTimer ) )"
* {
* // xTimer is already active - delete it.
* xTimerDelete( xTimer );
* }
* else
* {
* // xTimer is not active, change its period to 500ms. This will also
* // cause the timer to start. Block for a maximum of 100 ticks if the
* // change period command cannot immediately be sent to the timer
* // command queue.
* if( xTimerChangePeriod( xTimer, 500 / portTICK_RATE_MS, 100 ) == pdPASS )
* {
* // The command was successfully sent.
* }
* else
* {
* // The command could not be sent, even after waiting for 100 ticks
* // to pass. Take appropriate action here.
* }
* }
* }
*/
#define xTimerChangePeriod( xTimer, xNewPeriod, xBlockTime ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_CHANGE_PERIOD, ( xNewPeriod ), NULL, ( xBlockTime ) )
/**
* portBASE_TYPE xTimerDelete( xTimerHandle xTimer, portTickType xBlockTime );
*
* Timer functionality is provided by a timer service/daemon task. Many of the
* public FreeRTOS timer API functions send commands to the timer service task
* though a queue called the timer command queue. The timer command queue is
* private to the kernel itself and is not directly accessible to application
* code. The length of the timer command queue is set by the
* configTIMER_QUEUE_LENGTH configuration constant.
*
* xTimerDelete() deletes a timer that was previously created using the
* xTimerCreate() API function.
*
* The configUSE_TIMERS configuration constant must be set to 1 for
* xTimerDelete() to be available.
*
* @param xTimer The handle of the timer being deleted.
*
* @param xBlockTime Specifies the time, in ticks, that the calling task should
* be held in the Blocked state to wait for the delete command to be
* successfully sent to the timer command queue, should the queue already be
* full when xTimerDelete() was called. xBlockTime is ignored if xTimerDelete()
* is called before the scheduler is started.
*
* @return pdFAIL will be returned if the delete command could not be sent to
* the timer command queue even after xBlockTime ticks had passed. pdPASS will
* be returned if the command was successfully sent to the timer command queue.
* When the command is actually processed will depend on the priority of the
* timer service/daemon task relative to other tasks in the system. The timer
* service/daemon task priority is set by the configTIMER_TASK_PRIORITY
* configuration constant.
*
* Example usage:
*
* See the xTimerChangePeriod() API function example usage scenario.
*/
#define xTimerDelete( xTimer, xBlockTime ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_DELETE, 0U, NULL, ( xBlockTime ) )
/**
* portBASE_TYPE xTimerReset( xTimerHandle xTimer, portTickType xBlockTime );
*
* Timer functionality is provided by a timer service/daemon task. Many of the
* public FreeRTOS timer API functions send commands to the timer service task
* though a queue called the timer command queue. The timer command queue is
* private to the kernel itself and is not directly accessible to application
* code. The length of the timer command queue is set by the
* configTIMER_QUEUE_LENGTH configuration constant.
*
* xTimerReset() re-starts a timer that was previously created using the
* xTimerCreate() API function. If the timer had already been started and was
* already in the active state, then xTimerReset() will cause the timer to
* re-evaluate its expiry time so that it is relative to when xTimerReset() was
* called. If the timer was in the dormant state then xTimerReset() has
* equivalent functionality to the xTimerStart() API function.
*
* Resetting a timer ensures the timer is in the active state. If the timer
* is not stopped, deleted, or reset in the mean time, the callback function
* associated with the timer will get called 'n' ticks after xTimerReset() was
* called, where 'n' is the timers defined period.
*
* It is valid to call xTimerReset() before the scheduler has been started, but
* when this is done the timer will not actually start until the scheduler is
* started, and the timers expiry time will be relative to when the scheduler is
* started, not relative to when xTimerReset() was called.
*
* The configUSE_TIMERS configuration constant must be set to 1 for xTimerReset()
* to be available.
*
* @param xTimer The handle of the timer being reset/started/restarted.
*
* @param xBlockTime Specifies the time, in ticks, that the calling task should
* be held in the Blocked state to wait for the reset command to be successfully
* sent to the timer command queue, should the queue already be full when
* xTimerReset() was called. xBlockTime is ignored if xTimerReset() is called
* before the scheduler is started.
*
* @return pdFAIL will be returned if the reset command could not be sent to
* the timer command queue even after xBlockTime ticks had passed. pdPASS will
* be returned if the command was successfully sent to the timer command queue.
* When the command is actually processed will depend on the priority of the
* timer service/daemon task relative to other tasks in the system, although the
* timers expiry time is relative to when xTimerStart() is actually called. The
* timer service/daemon task priority is set by the configTIMER_TASK_PRIORITY
* configuration constant.
*
* Example usage:
*
* // When a key is pressed, an LCD back-light is switched on. If 5 seconds pass
* // without a key being pressed, then the LCD back-light is switched off. In
* // this case, the timer is a one-shot timer.
*
* xTimerHandle xBacklightTimer = NULL;
*
* // The callback function assigned to the one-shot timer. In this case the
* // parameter is not used.
* void vBacklightTimerCallback( xTimerHandle pxTimer )
* {
* // The timer expired, therefore 5 seconds must have passed since a key
* // was pressed. Switch off the LCD back-light.
* vSetBacklightState( BACKLIGHT_OFF );
* }
*
* // The key press event handler.
* void vKeyPressEventHandler( char cKey )
* {
* // Ensure the LCD back-light is on, then reset the timer that is
* // responsible for turning the back-light off after 5 seconds of
* // key inactivity. Wait 10 ticks for the command to be successfully sent
* // if it cannot be sent immediately.
* vSetBacklightState( BACKLIGHT_ON );
* if( xTimerReset( xBacklightTimer, 100 ) != pdPASS )
* {
* // The reset command was not executed successfully. Take appropriate
* // action here.
* }
*
* // Perform the rest of the key processing here.
* }
*
* void main( void )
* {
* long x;
*
* // Create then start the one-shot timer that is responsible for turning
* // the back-light off if no keys are pressed within a 5 second period.
* xBacklightTimer = xTimerCreate( "BacklightTimer", // Just a text name, not used by the kernel.
* ( 5000 / portTICK_RATE_MS), // The timer period in ticks.
* pdFALSE, // The timer is a one-shot timer.
* 0, // The id is not used by the callback so can take any value.
* vBacklightTimerCallback // The callback function that switches the LCD back-light off.
* );
*
* if( xBacklightTimer == NULL )
* {
* // The timer was not created.
* }
* else
* {
* // Start the timer. No block time is specified, and even if one was
* // it would be ignored because the scheduler has not yet been
* // started.
* if( xTimerStart( xBacklightTimer, 0 ) != pdPASS )
* {
* // The timer could not be set into the Active state.
* }
* }
*
* // ...
* // Create tasks here.
* // ...
*
* // Starting the scheduler will start the timer running as it has already
* // been set into the active state.
* xTaskStartScheduler();
*
* // Should not reach here.
* for( ;; );
* }
*/
#define xTimerReset( xTimer, xBlockTime ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_START, ( xTaskGetTickCount() ), NULL, ( xBlockTime ) )
/**
* portBASE_TYPE xTimerStartFromISR( xTimerHandle xTimer,
* portBASE_TYPE *pxHigherPriorityTaskWoken );
*
* A version of xTimerStart() that can be called from an interrupt service
* routine.
*
* @param xTimer The handle of the timer being started/restarted.
*
* @param pxHigherPriorityTaskWoken The timer service/daemon task spends most
* of its time in the Blocked state, waiting for messages to arrive on the timer
* command queue. Calling xTimerStartFromISR() writes a message to the timer
* command queue, so has the potential to transition the timer service/daemon
* task out of the Blocked state. If calling xTimerStartFromISR() causes the
* timer service/daemon task to leave the Blocked state, and the timer service/
* daemon task has a priority equal to or greater than the currently executing
* task (the task that was interrupted), then *pxHigherPriorityTaskWoken will
* get set to pdTRUE internally within the xTimerStartFromISR() function. If
* xTimerStartFromISR() sets this value to pdTRUE then a context switch should
* be performed before the interrupt exits.
*
* @return pdFAIL will be returned if the start command could not be sent to
* the timer command queue. pdPASS will be returned if the command was
* successfully sent to the timer command queue. When the command is actually
* processed will depend on the priority of the timer service/daemon task
* relative to other tasks in the system, although the timers expiry time is
* relative to when xTimerStartFromISR() is actually called. The timer service/daemon
* task priority is set by the configTIMER_TASK_PRIORITY configuration constant.
*
* Example usage:
*
* // This scenario assumes xBacklightTimer has already been created. When a
* // key is pressed, an LCD back-light is switched on. If 5 seconds pass
* // without a key being pressed, then the LCD back-light is switched off. In
* // this case, the timer is a one-shot timer, and unlike the example given for
* // the xTimerReset() function, the key press event handler is an interrupt
* // service routine.
*
* // The callback function assigned to the one-shot timer. In this case the
* // parameter is not used.
* void vBacklightTimerCallback( xTimerHandle pxTimer )
* {
* // The timer expired, therefore 5 seconds must have passed since a key
* // was pressed. Switch off the LCD back-light.
* vSetBacklightState( BACKLIGHT_OFF );
* }
*
* // The key press interrupt service routine.
* void vKeyPressEventInterruptHandler( void )
* {
* portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
*
* // Ensure the LCD back-light is on, then restart the timer that is
* // responsible for turning the back-light off after 5 seconds of
* // key inactivity. This is an interrupt service routine so can only
* // call FreeRTOS API functions that end in "FromISR".
* vSetBacklightState( BACKLIGHT_ON );
*
* // xTimerStartFromISR() or xTimerResetFromISR() could be called here
* // as both cause the timer to re-calculate its expiry time.
* // xHigherPriorityTaskWoken was initialised to pdFALSE when it was
* // declared (in this function).
* if( xTimerStartFromISR( xBacklightTimer, &xHigherPriorityTaskWoken ) != pdPASS )
* {
* // The start command was not executed successfully. Take appropriate
* // action here.
* }
*
* // Perform the rest of the key processing here.
*
* // If xHigherPriorityTaskWoken equals pdTRUE, then a context switch
* // should be performed. The syntax required to perform a context switch
* // from inside an ISR varies from port to port, and from compiler to
* // compiler. Inspect the demos for the port you are using to find the
* // actual syntax required.
* if( xHigherPriorityTaskWoken != pdFALSE )
* {
* // Call the interrupt safe yield function here (actual function
* // depends on the FreeRTOS port being used.
* }
* }
*/
#define xTimerStartFromISR( xTimer, pxHigherPriorityTaskWoken ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_START, ( xTaskGetTickCountFromISR() ), ( pxHigherPriorityTaskWoken ), 0U )
/**
* portBASE_TYPE xTimerStopFromISR( xTimerHandle xTimer,
* portBASE_TYPE *pxHigherPriorityTaskWoken );
*
* A version of xTimerStop() that can be called from an interrupt service
* routine.
*
* @param xTimer The handle of the timer being stopped.
*
* @param pxHigherPriorityTaskWoken The timer service/daemon task spends most
* of its time in the Blocked state, waiting for messages to arrive on the timer
* command queue. Calling xTimerStopFromISR() writes a message to the timer
* command queue, so has the potential to transition the timer service/daemon
* task out of the Blocked state. If calling xTimerStopFromISR() causes the
* timer service/daemon task to leave the Blocked state, and the timer service/
* daemon task has a priority equal to or greater than the currently executing
* task (the task that was interrupted), then *pxHigherPriorityTaskWoken will
* get set to pdTRUE internally within the xTimerStopFromISR() function. If
* xTimerStopFromISR() sets this value to pdTRUE then a context switch should
* be performed before the interrupt exits.
*
* @return pdFAIL will be returned if the stop command could not be sent to
* the timer command queue. pdPASS will be returned if the command was
* successfully sent to the timer command queue. When the command is actually
* processed will depend on the priority of the timer service/daemon task
* relative to other tasks in the system. The timer service/daemon task
* priority is set by the configTIMER_TASK_PRIORITY configuration constant.
*
* Example usage:
*
* // This scenario assumes xTimer has already been created and started. When
* // an interrupt occurs, the timer should be simply stopped.
*
* // The interrupt service routine that stops the timer.
* void vAnExampleInterruptServiceRoutine( void )
* {
* portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
*
* // The interrupt has occurred - simply stop the timer.
* // xHigherPriorityTaskWoken was set to pdFALSE where it was defined
* // (within this function). As this is an interrupt service routine, only
* // FreeRTOS API functions that end in "FromISR" can be used.
* if( xTimerStopFromISR( xTimer, &xHigherPriorityTaskWoken ) != pdPASS )
* {
* // The stop command was not executed successfully. Take appropriate
* // action here.
* }
*
* // If xHigherPriorityTaskWoken equals pdTRUE, then a context switch
* // should be performed. The syntax required to perform a context switch
* // from inside an ISR varies from port to port, and from compiler to
* // compiler. Inspect the demos for the port you are using to find the
* // actual syntax required.
* if( xHigherPriorityTaskWoken != pdFALSE )
* {
* // Call the interrupt safe yield function here (actual function
* // depends on the FreeRTOS port being used.
* }
* }
*/
#define xTimerStopFromISR( xTimer, pxHigherPriorityTaskWoken ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_STOP, 0, ( pxHigherPriorityTaskWoken ), 0U )
/**
* portBASE_TYPE xTimerChangePeriodFromISR( xTimerHandle xTimer,
* portTickType xNewPeriod,
* portBASE_TYPE *pxHigherPriorityTaskWoken );
*
* A version of xTimerChangePeriod() that can be called from an interrupt
* service routine.
*
* @param xTimer The handle of the timer that is having its period changed.
*
* @param xNewPeriod The new period for xTimer. Timer periods are specified in
* tick periods, so the constant portTICK_RATE_MS can be used to convert a time
* that has been specified in milliseconds. For example, if the timer must
* expire after 100 ticks, then xNewPeriod should be set to 100. Alternatively,
* if the timer must expire after 500ms, then xNewPeriod can be set to
* ( 500 / portTICK_RATE_MS ) provided configTICK_RATE_HZ is less than
* or equal to 1000.
*
* @param pxHigherPriorityTaskWoken The timer service/daemon task spends most
* of its time in the Blocked state, waiting for messages to arrive on the timer
* command queue. Calling xTimerChangePeriodFromISR() writes a message to the
* timer command queue, so has the potential to transition the timer service/
* daemon task out of the Blocked state. If calling xTimerChangePeriodFromISR()
* causes the timer service/daemon task to leave the Blocked state, and the
* timer service/daemon task has a priority equal to or greater than the
* currently executing task (the task that was interrupted), then
* *pxHigherPriorityTaskWoken will get set to pdTRUE internally within the
* xTimerChangePeriodFromISR() function. If xTimerChangePeriodFromISR() sets
* this value to pdTRUE then a context switch should be performed before the
* interrupt exits.
*
* @return pdFAIL will be returned if the command to change the timers period
* could not be sent to the timer command queue. pdPASS will be returned if the
* command was successfully sent to the timer command queue. When the command
* is actually processed will depend on the priority of the timer service/daemon
* task relative to other tasks in the system. The timer service/daemon task
* priority is set by the configTIMER_TASK_PRIORITY configuration constant.
*
* Example usage:
*
* // This scenario assumes xTimer has already been created and started. When
* // an interrupt occurs, the period of xTimer should be changed to 500ms.
*
* // The interrupt service routine that changes the period of xTimer.
* void vAnExampleInterruptServiceRoutine( void )
* {
* portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
*
* // The interrupt has occurred - change the period of xTimer to 500ms.
* // xHigherPriorityTaskWoken was set to pdFALSE where it was defined
* // (within this function). As this is an interrupt service routine, only
* // FreeRTOS API functions that end in "FromISR" can be used.
* if( xTimerChangePeriodFromISR( xTimer, &xHigherPriorityTaskWoken ) != pdPASS )
* {
* // The command to change the timers period was not executed
* // successfully. Take appropriate action here.
* }
*
* // If xHigherPriorityTaskWoken equals pdTRUE, then a context switch
* // should be performed. The syntax required to perform a context switch
* // from inside an ISR varies from port to port, and from compiler to
* // compiler. Inspect the demos for the port you are using to find the
* // actual syntax required.
* if( xHigherPriorityTaskWoken != pdFALSE )
* {
* // Call the interrupt safe yield function here (actual function
* // depends on the FreeRTOS port being used.
* }
* }
*/
#define xTimerChangePeriodFromISR( xTimer, xNewPeriod, pxHigherPriorityTaskWoken ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_CHANGE_PERIOD, ( xNewPeriod ), ( pxHigherPriorityTaskWoken ), 0U )
/**
* portBASE_TYPE xTimerResetFromISR( xTimerHandle xTimer,
* portBASE_TYPE *pxHigherPriorityTaskWoken );
*
* A version of xTimerReset() that can be called from an interrupt service
* routine.
*
* @param xTimer The handle of the timer that is to be started, reset, or
* restarted.
*
* @param pxHigherPriorityTaskWoken The timer service/daemon task spends most
* of its time in the Blocked state, waiting for messages to arrive on the timer
* command queue. Calling xTimerResetFromISR() writes a message to the timer
* command queue, so has the potential to transition the timer service/daemon
* task out of the Blocked state. If calling xTimerResetFromISR() causes the
* timer service/daemon task to leave the Blocked state, and the timer service/
* daemon task has a priority equal to or greater than the currently executing
* task (the task that was interrupted), then *pxHigherPriorityTaskWoken will
* get set to pdTRUE internally within the xTimerResetFromISR() function. If
* xTimerResetFromISR() sets this value to pdTRUE then a context switch should
* be performed before the interrupt exits.
*
* @return pdFAIL will be returned if the reset command could not be sent to
* the timer command queue. pdPASS will be returned if the command was
* successfully sent to the timer command queue. When the command is actually
* processed will depend on the priority of the timer service/daemon task
* relative to other tasks in the system, although the timers expiry time is
* relative to when xTimerResetFromISR() is actually called. The timer service/daemon
* task priority is set by the configTIMER_TASK_PRIORITY configuration constant.
*
* Example usage:
*
* // This scenario assumes xBacklightTimer has already been created. When a
* // key is pressed, an LCD back-light is switched on. If 5 seconds pass
* // without a key being pressed, then the LCD back-light is switched off. In
* // this case, the timer is a one-shot timer, and unlike the example given for
* // the xTimerReset() function, the key press event handler is an interrupt
* // service routine.
*
* // The callback function assigned to the one-shot timer. In this case the
* // parameter is not used.
* void vBacklightTimerCallback( xTimerHandle pxTimer )
* {
* // The timer expired, therefore 5 seconds must have passed since a key
* // was pressed. Switch off the LCD back-light.
* vSetBacklightState( BACKLIGHT_OFF );
* }
*
* // The key press interrupt service routine.
* void vKeyPressEventInterruptHandler( void )
* {
* portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
*
* // Ensure the LCD back-light is on, then reset the timer that is
* // responsible for turning the back-light off after 5 seconds of
* // key inactivity. This is an interrupt service routine so can only
* // call FreeRTOS API functions that end in "FromISR".
* vSetBacklightState( BACKLIGHT_ON );
*
* // xTimerStartFromISR() or xTimerResetFromISR() could be called here
* // as both cause the timer to re-calculate its expiry time.
* // xHigherPriorityTaskWoken was initialised to pdFALSE when it was
* // declared (in this function).
* if( xTimerResetFromISR( xBacklightTimer, &xHigherPriorityTaskWoken ) != pdPASS )
* {
* // The reset command was not executed successfully. Take appropriate
* // action here.
* }
*
* // Perform the rest of the key processing here.
*
* // If xHigherPriorityTaskWoken equals pdTRUE, then a context switch
* // should be performed. The syntax required to perform a context switch
* // from inside an ISR varies from port to port, and from compiler to
* // compiler. Inspect the demos for the port you are using to find the
* // actual syntax required.
* if( xHigherPriorityTaskWoken != pdFALSE )
* {
* // Call the interrupt safe yield function here (actual function
* // depends on the FreeRTOS port being used.
* }
* }
*/
#define xTimerResetFromISR( xTimer, pxHigherPriorityTaskWoken ) xTimerGenericCommand( ( xTimer ), tmrCOMMAND_START, ( xTaskGetTickCountFromISR() ), ( pxHigherPriorityTaskWoken ), 0U )
/*
* Functions beyond this part are not part of the public API and are intended
* for use by the kernel only.
*/
portBASE_TYPE xTimerCreateTimerTask( void ) PRIVILEGED_FUNCTION;
portBASE_TYPE xTimerGenericCommand( xTimerHandle xTimer, portBASE_TYPE xCommandID, portTickType xOptionalValue, signed portBASE_TYPE *pxHigherPriorityTaskWoken, portTickType xBlockTime ) PRIVILEGED_FUNCTION;
#ifdef __cplusplus
}
#endif
#endif /* TIMERS_H */