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/*
* FreeRTOS Kernel V10.4.0
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/******************************************************************************
* NOTE: This file only contains the source code that is specific to the
* basic demo. Generic functions, such FreeRTOS hook functions, are defined
* in main.c.
******************************************************************************
*
* main_blinky() creates one queue, one software timer, and two tasks. It then
* starts the scheduler.
*
* The Queue Send Task:
* The queue send task is implemented by the prvQueueSendTask() function in
* this file. It uses vTaskDelayUntil() to create a periodic task that sends
* the value 100 to the queue every 200 milliseconds.
*
* The Queue Send Software Timer:
* The timer is an auto-reload timer with a period of two seconds. The timer's
* callback function writes the value 200 to the queue. The callback function
* is implemented by prvQueueSendTimerCallback() within this file.
*
* The Queue Receive Task:
* The queue receive task is implemented by the prvQueueReceiveTask() function
* in this file. prvQueueReceiveTask() waits for data to arrive on the queue.
* When data is received, the task checks the value of the data, then outputs a
* message to indicate if the data came from the queue send task or the queue
* send software timer.
*
* Expected Behavior:
* - The queue send task writes to the queue every 200ms, so every 200ms the
* queue receive task will output a message indicating that data was received
* on the queue from the queue send task.
* - The queue send software timer has a period of two seconds, so every two
* seconds the queue receive task will output a message indicating that data
* was received on the queue from the queue send software timer.
*/
/* Standard includes. */
#include <stdio.h>
/* Kernel includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "timers.h"
#include "semphr.h"
/**
* Priorities at which the tasks are created.
*/
#define mainQUEUE_RECEIVE_TASK_PRIORITY ( tskIDLE_PRIORITY + 2 )
#define mainQUEUE_SEND_TASK_PRIORITY ( tskIDLE_PRIORITY + 1 )
/**
* The rate at which data is sent to the queue. The times are converted from
* milliseconds to ticks using the pdMS_TO_TICKS() macro.
*/
#define mainTASK_SEND_FREQUENCY_MS pdMS_TO_TICKS( 200UL )
#define mainTIMER_SEND_FREQUENCY_MS pdMS_TO_TICKS( 2000UL )
/**
* The number of items the queue can hold at once.
*/
#define mainQUEUE_LENGTH ( 2 )
/**
* The values sent to the queue receive task from the queue send task and the
* queue send software timer respectively.
*/
#define mainVALUE_SENT_FROM_TASK ( 100UL )
#define mainVALUE_SENT_FROM_TIMER ( 200UL )
/*-----------------------------------------------------------*/
/**
* The tasks as described in the comments at the top of this file.
*/
static void prvQueueReceiveTask( void *pvParameters );
static void prvQueueSendTask( void *pvParameters );
/**
* The callback function executed when the software timer expires.
*/
static void prvQueueSendTimerCallback( TimerHandle_t xTimerHandle );
/*-----------------------------------------------------------*/
/**
* The queue used by both tasks.
*/
static QueueHandle_t xQueue = NULL;
/**
* A software timer that is started from the tick hook.
*/
static TimerHandle_t xTimer = NULL;
/*-----------------------------------------------------------*/
void main_blinky( void )
{
const TickType_t xTimerPeriod = mainTIMER_SEND_FREQUENCY_MS;
/* Create the queue. */
xQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( uint32_t ) );
if( xQueue != NULL )
{
/* Start the two tasks as described in the comments at the top of this
* file. */
xTaskCreate( prvQueueReceiveTask, /* The function that implements the task. */
"Rx", /* The text name assigned to the task - for debug only as it is not used by the kernel. */
configMINIMAL_STACK_SIZE, /* The size of the stack to allocate to the task. */
NULL, /* The parameter passed to the task - not used in this simple case. */
mainQUEUE_RECEIVE_TASK_PRIORITY,/* The priority assigned to the task. */
NULL ); /* The task handle is not required, so NULL is passed. */
xTaskCreate( prvQueueSendTask, "TX", configMINIMAL_STACK_SIZE, NULL, mainQUEUE_SEND_TASK_PRIORITY, NULL );
/* Create the software timer, but don't start it yet. */
xTimer = xTimerCreate( "Timer", /* The text name assigned to the software timer - for debug only as it is not used by the kernel. */
xTimerPeriod, /* The period of the software timer in ticks. */
pdTRUE, /* xAutoReload is set to pdTRUE. */
NULL, /* The timer's ID is not used. */
prvQueueSendTimerCallback );/* The function executed when the timer expires. */
if( xTimer != NULL )
{
xTimerStart( xTimer, 0 );
}
/* Start the tasks and timer running. */
vTaskStartScheduler();
}
/* If all is well, the scheduler will now be running, and the following
* line will never be reached. If the following line does execute, then
* there was insufficient FreeRTOS heap memory available for the idle and/or
* timer tasks to be created. See the memory management section on the
* FreeRTOS web site for more details. */
for( ;; );
}
/*-----------------------------------------------------------*/
static void prvQueueSendTask( void *pvParameters )
{
TickType_t xNextWakeTime;
const TickType_t xBlockTime = mainTASK_SEND_FREQUENCY_MS;
const uint32_t ulValueToSend = mainVALUE_SENT_FROM_TASK;
/* Prevent the compiler warning about the unused parameter. */
( void ) pvParameters;
/* Initialise xNextWakeTime - this only needs to be done once. */
xNextWakeTime = xTaskGetTickCount();
for( ;; )
{
/* Place this task in the blocked state until it is time to run again.
* The block time is specified in ticks, pdMS_TO_TICKS() was used to
* convert a time specified in milliseconds into a time specified in ticks.
* While in the Blocked state this task will not consume any CPU time. */
vTaskDelayUntil( &xNextWakeTime, xBlockTime );
/* Send to the queue - causing the queue receive task to unblock and
* write to the console. 0 is used as the block time so the send operation
* will not block - it shouldn't need to block as the queue should always
* have at least one space at this point in the code. */
xQueueSend( xQueue, &ulValueToSend, 0U );
}
}
/*-----------------------------------------------------------*/
static void prvQueueSendTimerCallback( TimerHandle_t xTimerHandle )
{
const uint32_t ulValueToSend = mainVALUE_SENT_FROM_TIMER;
/* This is the software timer callback function. The software timer has a
* period of two seconds and is reset each time a key is pressed. This
* callback function will execute if the timer expires, which will only happen
* if a key is not pressed for two seconds. */
/* Avoid compiler warnings resulting from the unused parameter. */
( void ) xTimerHandle;
/* Send to the queue - causing the queue receive task to unblock and
* write out a message. This function is called from the timer/daemon task,
* so must not block. Hence the block time is set to 0. */
xQueueSend( xQueue, &ulValueToSend, 0U );
}
/*-----------------------------------------------------------*/
static void prvQueueReceiveTask( void *pvParameters )
{
uint32_t ulReceivedValue;
/* Prevent the compiler warning about the unused parameter. */
( void ) pvParameters;
for( ;; )
{
/* Wait until something arrives in the queue - this task will block
* indefinitely provided INCLUDE_vTaskSuspend is set to 1 in
* FreeRTOSConfig.h. It will not use any CPU time while it is in the
* Blocked state. */
xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );
/* To get here something must have been received from the queue, but
* is it an expected value? This is the only task that uses stdout so its
* ok to call printf() directly. Do not call printf from any other task. */
if( ulReceivedValue == mainVALUE_SENT_FROM_TASK )
{
printf( "Message received from task\r\n" );
}
else if( ulReceivedValue == mainVALUE_SENT_FROM_TIMER )
{
printf( "Message received from software timer\r\n" );
}
else
{
printf( "Unexpected message\r\n" );
}
fflush( stdout );
}
}
/*-----------------------------------------------------------*/
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