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diff --git a/libraries/FreeRTOS/utility/timers.h b/libraries/FreeRTOS/utility/timers.h new file mode 100755 index 0000000..f1bcb0d --- /dev/null +++ b/libraries/FreeRTOS/utility/timers.h @@ -0,0 +1,936 @@ +/* + FreeRTOS V7.0.1 - Copyright (C) 2011 Real Time Engineers Ltd. + + + FreeRTOS supports many tools and architectures. V7.0.0 is sponsored by: + Atollic AB - Atollic provides professional embedded systems development + tools for C/C++ development, code analysis and test automation. + See http://www.atollic.com + + + *************************************************************************** + * * + * 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 + distribute a combined work that includes FreeRTOS without being obliged to + provide the source code for proprietary components outside of the FreeRTOS + kernel. FreeRTOS is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY + or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + more details. You should have received a copy of the GNU General Public + License 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 Richard Barry, contact details for whom are available on the + FreeRTOS WEB site. + + 1 tab == 4 spaces! + + http://www.FreeRTOS.org - Documentation, latest information, license and + contact details. + + http://www.SafeRTOS.com - A version that is certified for use in safety + critical systems. + + http://www.OpenRTOS.com - Commercial support, development, porting, + licensing and training services. +*/ + + +#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" + +#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 xTimerPeriod, + * 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 xTimerPeriod 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 xTimerPeriod 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 xTimerPeriod 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( xTIMER *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( xTIMER *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 *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; + +/** + * 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( xTIMER *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( xTIMER *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( xTIMER *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, portBASE_TYPE *pxHigherPriorityTaskWoken, portTickType xBlockTime ) PRIVILEGED_FUNCTION; + +#ifdef __cplusplus +} +#endif +#endif /* TIMERS_H */ + + + |