2 * FreeRTOS Kernel V10.0.1
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3 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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5 * Permission is hereby granted, free of charge, to any person obtaining a copy of
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6 * this software and associated documentation files (the "Software"), to deal in
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7 * the Software without restriction, including without limitation the rights to
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8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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9 * the Software, and to permit persons to whom the Software is furnished to do so,
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10 * subject to the following conditions:
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12 * The above copyright notice and this permission notice shall be included in all
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13 * copies or substantial portions of the Software.
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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22 * http://www.FreeRTOS.org
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23 * http://aws.amazon.com/freertos
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25 * 1 tab == 4 spaces!
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29 * This file defines the button push task and ISR as described at the top of
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30 * main.c. The ISR is called from a wrapper function defined in ButtonISR.s26.
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33 /* Kernel includes. */
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34 #include "FreeRTOS.h"
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38 /* The LED output used by the button push task. */
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39 #define butLED1 P7_bit.no7
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41 /* A short delay used for button debouncing. */
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42 #define butDEBOUNCE_DELAY ( 200 / portTICK_PERIOD_MS )
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44 /* The semaphore used to synchronise the button push task with the interrupt. */
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45 static SemaphoreHandle_t xButtonSemaphore;
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48 * The definition of the button task itself. See the comments at the top of
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51 void vButtonTask( void *pvParameters )
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53 /* Ensure the semaphore is created before it gets used. */
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54 vSemaphoreCreateBinary( xButtonSemaphore );
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58 /* Block on the semaphore to wait for an interrupt event. The semaphore
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59 is 'given' from vButtonISRHandler() below. Using portMAX_DELAY as the
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60 block time will cause the task to block indefinitely provided
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61 INCLUDE_vTaskSuspend is set to 1 in FreeRTOSConfig.h. */
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62 xSemaphoreTake( xButtonSemaphore, portMAX_DELAY );
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64 /* The button must have been pushed for this line to be executed.
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65 Simply toggle the LED. */
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68 /* Wait a short time then clear any pending button pushes as a crude
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69 method of debouncing the switch. xSemaphoreTake() uses a block time of
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70 zero this time so it returns immediately rather than waiting for the
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71 interrupt to occur. */
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72 vTaskDelay( butDEBOUNCE_DELAY );
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73 xSemaphoreTake( xButtonSemaphore, 0 );
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76 /*-----------------------------------------------------------*/
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79 * The C portion of the interrupt handler. Interrupts are triggered by pushing
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80 * the button on the target board. This interrupt can cause a context switch
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81 * so has an assembly file wrapper defined within ButtonISR.s26.
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83 void vButtonISRHandler( void )
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85 short sHigherPriorityTaskWoken = pdFALSE;
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87 /* 'Give' the semaphore to unblock the button task. */
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88 xSemaphoreGiveFromISR( xButtonSemaphore, &sHigherPriorityTaskWoken );
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90 /* If giving the semaphore unblocked a task, and the unblocked task has a
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91 priority that is higher than the currently running task, then
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92 sHigherPriorityTaskWoken will have been set to pdTRUE. Passing a pdTRUE
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93 value to portYIELD_FROM_ISR() will cause this interrupt to return directly
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94 to the higher priority unblocked task. */
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95 portYIELD_FROM_ISR( sHigherPriorityTaskWoken );
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97 /*-----------------------------------------------------------*/
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