FreeRTOS/Demo/CORTEX_EFM32_Giant_Gecko_Simplicity_Studio/Low_Power_Demo/main_low_power.c

/*
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    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.

    ***************************************************************************
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    >>!   outside of the FreeRTOS kernel.                                   !<<
    ***************************************************************************

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    ***************************************************************************
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*/

/******************************************************************************
 * NOTE 1:  This project provides two demo applications.  A simple blinky demo
 * that demonstrates tickless low power operation, and a more comprehensive
 * test and demo application.  The configCREATE_LOW_POWER_DEMO setting in
 * FreeRTOSConfig.h is used to select between the two, and to select the clock
 * used when tickless low power operation is demonstrated.  See the notes on
 * using configCREATE_LOW_POWER_DEMO in main.c.  This file implements the low
 * power version.
 *
 * NOTE 2:  This file only contains the source code that is specific to the
 * low power demo.  Generic functions, such FreeRTOS hook functions, and
 * functions required to configure the hardware are defined in main.c.
 ******************************************************************************
 *
 * main_low_power() creates one queue, 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 sends the value 100 to the queue every second.
 *
 * The Queue Receive Task:
 * The queue receive task is implemented by the prvQueueReceiveTask() function
 * in this file.  prvQueueReceiveTask() blocks on the queue, blipping (quickly
 * turn on then off again) the LED each time it received the value 100 from the
 * queue send task.  The queue send task writes to the queue every second, so
 * the LED will blip once a second.
 *
 * The RTOS tick is turned off when the queue send task and queue receive task
 * are both in the Blocked state.
 *
 */


/* Kernel includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "semphr.h"

/* SiLabs includes. */
#include "bsp.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 200ms value is converted
to ticks using the portTICK_PERIOD_MS constant. */
#define mainQUEUE_SEND_FREQUENCY_MS			pdMS_TO_TICKS( 1000 )

/* The number of items the queue can hold.  This is 1 as the receive task
will remove items as they are added, meaning the send task should always find
the queue empty. */
#define mainQUEUE_LENGTH					( 1 )

/* The LED toggled by the Rx task. */
#define mainTASK_LED						( 0 )

/*-----------------------------------------------------------*/

/*
 * Called by main when mainCREATE_LOW_POWER_DEMO is set to 1 in
 * main.c.
 */
void main_low_power( void );

/*
 * The tasks as described in the comments at the top of this file.
 */
static void prvQueueReceiveTask( void *pvParameters );
static void prvQueueSendTask( void *pvParameters );

/*-----------------------------------------------------------*/

/* The queue used by both tasks. */
static QueueHandle_t xQueue = NULL;

/*-----------------------------------------------------------*/

void main_low_power( void )
{
	/* 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 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 );

		/* 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 on the FreeRTOS heap
	http://www.freertos.org/a00111.html. */
	for( ;; );
}
/*-----------------------------------------------------------*/

static void prvQueueSendTask( void *pvParameters )
{
TickType_t xNextWakeTime;
const uint32_t ulValueToSend = 100UL;

	/* Remove compiler warning about 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. */
		vTaskDelayUntil( &xNextWakeTime, mainQUEUE_SEND_FREQUENCY_MS );

		/* Send to the queue - causing the queue receive task to unblock and
		toggle the LED.  0 is used as the block time so the sending operation
		will not block - it shouldn't need to block as the queue should always
		be empty at this point in the code. */
		xQueueSend( xQueue, &ulValueToSend, 0U );
	}
}
/*-----------------------------------------------------------*/

static void prvQueueReceiveTask( void *pvParameters )
{
uint32_t ulReceivedValue;
const uint32_t ulExpectedValue = 100UL;
const TickType_t xShortDelay = pdMS_TO_TICKS( 10 );

	/* Remove compiler warning about 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. */
		xQueueReceive( xQueue, &ulReceivedValue, portMAX_DELAY );

		/*  To get here something must have been received from the queue, but
		is it the expected value?  If it is, toggle the LED. */
		if( ulReceivedValue == ulExpectedValue )
		{
			/* Turn the LED on for a brief time only so it doens't distort the
			energy reading. */
			BSP_LedSet( mainTASK_LED );
			vTaskDelay( xShortDelay );
			BSP_LedClear( mainTASK_LED );
			ulReceivedValue = 0U;
		}
	}
}
/*-----------------------------------------------------------*/