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122 lines
4.9 KiB
C
122 lines
4.9 KiB
C
/*
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FreeRTOS.org V5.3.1 - Copyright (C) 2003-2009 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License (version 2) as published
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by the Free Software Foundation and modified by the FreeRTOS exception.
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**NOTE** The exception to the GPL is included to allow you to distribute a
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combined work that includes FreeRTOS.org without being obliged to provide
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the source code for any proprietary components. Alternative commercial
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license and support terms are also available upon request. See the
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licensing section of http://www.FreeRTOS.org for full details.
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FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along
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with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59
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Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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***************************************************************************
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* *
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* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
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* *
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* This is a concise, step by step, 'hands on' guide that describes both *
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* general multitasking concepts and FreeRTOS specifics. It presents and *
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* explains numerous examples that are written using the FreeRTOS API. *
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* Full source code for all the examples is provided in an accompanying *
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* .zip file. *
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* *
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***************************************************************************
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1 tab == 4 spaces!
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Please ensure to read the configuration and relevant port sections of the
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online documentation.
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*
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* This file defines the button push task and ISR as described at the top of
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* main.c. The ISR is called from a wrapper function defined in ButtonISR.s26.
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*/
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/* Kernel includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "semphr.h"
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/* The LED output used by the button push task. */
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#define butLED1 P7_bit.no7
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/* A short delay used for button debouncing. */
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#define butDEBOUNCE_DELAY ( 200 / portTICK_RATE_MS )
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/* The semaphore used to synchronise the button push task with the interrupt. */
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static xSemaphoreHandle xButtonSemaphore;
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/*
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* The definition of the button task itself. See the comments at the top of
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* main.c.
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*/
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void vButtonTask( void *pvParameters )
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{
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/* Ensure the semaphore is created before it gets used. */
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vSemaphoreCreateBinary( xButtonSemaphore );
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for( ;; )
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{
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/* Block on the semaphore to wait for an interrupt event. The semaphore
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is 'given' from vButtonISRHandler() below. Using portMAX_DELAY as the
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block time will cause the task to block indefinitely provided
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INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */
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xSemaphoreTake( xButtonSemaphore, portMAX_DELAY );
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/* The button must have been pushed for this line to be executed.
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Simply toggle the LED. */
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butLED1 = !butLED1;
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/* Wait a short time then clear any pending button pushes as a crude
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method of debouncing the switch. xSemaphoreTake() uses a block time of
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zero this time so it returns immediately rather than waiting for the
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interrupt to occur. */
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vTaskDelay( butDEBOUNCE_DELAY );
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xSemaphoreTake( xButtonSemaphore, 0 );
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}
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}
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/*-----------------------------------------------------------*/
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/*
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* The C portion of the interrupt handler. Interrupts are triggered by pushing
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* the button on the target board. This interrupt can cause a context switch
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* so has an assembly file wrapper defined within ButtonISR.s26.
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*/
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void vButtonISRHandler( void )
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{
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short sHigherPriorityTaskWoken = pdFALSE;
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/* 'Give' the semaphore to unblock the button task. */
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xSemaphoreGiveFromISR( xButtonSemaphore, &sHigherPriorityTaskWoken );
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/* If giving the semaphore unblocked a task, and the unblocked task has a
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priority that is higher than the currently running task, then
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sHigherPriorityTaskWoken will have been set to pdTRUE. Passing a pdTRUE
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value to portYIELD_FROM_ISR() will cause this interrupt to return directly
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to the higher priority unblocked task. */
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portYIELD_FROM_ISR( sHigherPriorityTaskWoken );
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}
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/*-----------------------------------------------------------*/
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