path: root/FreeRTOS/Demo/CORTEX_M4F_STM32F407ZG-SK/main.c

/*
 * FreeRTOS V202107.00
 * 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
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 * 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 1: <<<<<<
 *
 * main() can be configured to create either a very simple LED flasher demo, or
 * a more comprehensive test/demo application.
 *
 * To create a very simple LED flasher example, set the
 * mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY constant (defined below) to 1.  When
 * this is done, only the standard demo flash tasks are created.  The standard
 * demo flash example creates three tasks, each of which toggle an LED at a
 * fixed but different frequency.
 *
 * To create a more comprehensive test and demo application, set
 * mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY to 0.
 *
 * >>>>>> NOTE 2: <<<<<<
 *
 * In addition to the normal set of standard demo tasks, the comprehensive test
 * makes heavy use of the floating point unit, and forces floating point
 * instructions to be used from interrupts that nest three deep.  The nesting
 * starts from the tick hook function, resulting is an abnormally long context
 * switch time.  This is done purely to stress test the FPU context switching
 * implementation, and that part of the test can be removed by setting
 * configUSE_TICK_HOOK to 0 in FreeRTOSConfig.h.
 ******************************************************************************
 *
 * main() creates all the demo application tasks and software timers, then starts
 * the scheduler.  The web documentation provides more details of the standard
 * demo application tasks, which provide no particular functionality, but do
 * provide a good example of how to use the FreeRTOS API.
 *
 * In addition to the standard demo tasks, the following tasks and tests are
 * defined and/or created within this file:
 *
 * "Reg test" tasks - These fill both the core and floating point registers with
 * known values, then check that each register maintains its expected value for
 * the lifetime of the task.  Each task uses a different set of values.  The reg
 * test tasks execute with a very low priority, so get preempted very
 * frequently.  A register containing an unexpected value is indicative of an
 * error in the context switching mechanism.
 *
 * "Check" timer - The check software timer period is initially set to three
 * seconds.  The callback function associated with the check software timer
 * checks that all the standard demo tasks, and the register check tasks, are
 * not only still executing, but are executing without reporting any errors.  If
 * the check software timer discovers that a task has either stalled, or
 * reported an error, then it changes its own execution period from the initial
 * three seconds, to just 200ms.  The check software timer callback function
 * also toggles an LED each time it is called.  This provides a visual
 * indication of the system status:  If the LED toggles every three seconds,
 * then no issues have been discovered.  If the LED toggles every 200ms, then
 * an issue has been discovered with at least one task.
 *
 * Tick hook - The application tick hook is called from the schedulers tick
 * interrupt service routine when configUSE_TICK_HOOK is set to 1 in
 * FreeRTOSConfig.h.  In this example, the tick hook is used to test the kernels
 * handling of the floating point units (FPU) context, both at the task level
 * and when nesting interrupts access the floating point unit registers.  The
 * tick hook function first fills the FPU registers with a known value, it
 * then triggers a medium priority interrupt.  The medium priority interrupt
 * fills the FPU registers with a different value, and triggers a high priority
 * interrupt.  The high priority interrupt once again fills the the FPU
 * registers with a known value before returning to the medium priority
 * interrupt.  The medium priority interrupt checks that the FPU registers
 * contain the values that it wrote to them, then returns to the tick hook
 * function.  Finally, the tick hook function checks that the FPU registers
 * contain the values that it wrote to them, before it too returns.
 *
 * Button interrupt - The button marked "USER" on the starter kit is used to
 * demonstrate how to write an interrupt service routine, and how to synchronise
 * a task with an interrupt.  A task is created that blocks on a test semaphore.
 * When the USER button is pressed, the button interrupt handler gives the
 * semaphore, causing the task to unblock.  When the task unblocks, it simply
 * increments an execution count variable, then returns to block on the
 * semaphore again.
 */

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

/* Demo application includes. */
#include "partest.h"
#include "flash.h"
#include "flop.h"
#include "integer.h"
#include "PollQ.h"
#include "semtest.h"
#include "dynamic.h"
#include "BlockQ.h"
#include "blocktim.h"
#include "countsem.h"
#include "GenQTest.h"
#include "recmutex.h"
#include "death.h"

/* Hardware and starter kit includes. */
#include "arm_comm.h"
#include "iar_stm32f407zg_sk.h"
#include "stm32f4xx.h"
#include "stm32f4xx_conf.h"

/* Priorities for the demo application tasks. */
#define mainFLASH_TASK_PRIORITY				( tskIDLE_PRIORITY + 1UL )
#define mainQUEUE_POLL_PRIORITY				( tskIDLE_PRIORITY + 2UL )
#define mainSEM_TEST_PRIORITY				( tskIDLE_PRIORITY + 1UL )
#define mainBLOCK_Q_PRIORITY				( tskIDLE_PRIORITY + 2UL )
#define mainCREATOR_TASK_PRIORITY			( tskIDLE_PRIORITY + 3UL )
#define mainFLOP_TASK_PRIORITY				( tskIDLE_PRIORITY )

/* The LED used by the check timer. */
#define mainCHECK_LED 						( 3UL )

/* A block time of zero simply means "don't block". */
#define mainDONT_BLOCK						( 0UL )

/* The period after which the check timer will expire, in ms, provided no errors
have been reported by any of the standard demo tasks.  ms are converted to the
equivalent in ticks using the portTICK_PERIOD_MS constant. */
#define mainCHECK_TIMER_PERIOD_MS			( 3000UL / portTICK_PERIOD_MS )

/* The period at which the check timer will expire, in ms, if an error has been
reported in one of the standard demo tasks.  ms are converted to the equivalent
in ticks using the portTICK_PERIOD_MS constant. */
#define mainERROR_CHECK_TIMER_PERIOD_MS 	( 200UL / portTICK_PERIOD_MS )

/* Set mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY to 1 to create a simple demo.
Set mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY to 0 to create a much more
comprehensive test application.  See the comments at the top of this file, and
the documentation page on the http://www.FreeRTOS.org web site for more
information. */
#define mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY		0

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

/*
 * Set up the hardware ready to run this demo.
 */
static void prvSetupHardware( void );

/*
 * The check timer callback function, as described at the top of this file.
 */
static void prvCheckTimerCallback( TimerHandle_t xTimer );

/*
 * Configure the interrupts used to test the interrupt nesting depth as
 * described at the top of this file.
 */
static void prvSetupNestedFPUInterruptsTest( void );

/*
 * Register check tasks, and the tasks used to write over and check the contents
 * of the FPU registers, as described at the top of this file.  The nature of
 * these files necessitates that they are written in an assembly file.
 */
extern void vRegTest1Task( void *pvParameters );
extern void vRegTest2Task( void *pvParameters );
extern void vRegTestClearFlopRegistersToParameterValue( unsigned long ulValue );
extern unsigned long ulRegTestCheckFlopRegistersContainParameterValue( unsigned long ulValue );

/*
 * The task that is synchronised with the button interrupt.  This is done just
 * to demonstrate how to write interrupt service routines, and how to
 * synchronise a task with an interrupt.
 */
static void prvButtonTestTask( void *pvParameters );

/*
 * This file can be used to create either a simple LED flasher example, or a
 * comprehensive test/demo application - depending on the setting of the
 * mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY constant defined above.  If
 * mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY is set to 1, then the following
 * function will create a lot of additional tasks and a software timer.  If
 * mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY is set to 0, then the following
 * function will do nothing.
 */
static void prvOptionallyCreateComprehensveTestApplication( void );

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

/* The following two variables are used to communicate the status of the
register check tasks to the check software timer.  If the variables keep
incrementing, then the register check tasks have not discovered any errors.  If
a variable stops incrementing, then an error has been found. */
volatile unsigned long ulRegTest1LoopCounter = 0UL, ulRegTest2LoopCounter = 0UL;

/* The following variables are used to verify that the interrupt nesting depth
is as intended.  ulFPUInterruptNesting is incremented on entry to an interrupt
that uses the FPU, and decremented on exit of the same interrupt.
ulMaxFPUInterruptNesting latches the highest value reached by
ulFPUInterruptNesting.  These variables have no other purpose. */
volatile unsigned long ulFPUInterruptNesting = 0UL, ulMaxFPUInterruptNesting = 0UL;

/* The semaphore used to demonstrate a task being synchronised with an
interrupt. */
static SemaphoreHandle_t xTestSemaphore = NULL;

/* The variable that is incremented by the task synchronised with the button
interrupt. */
volatile unsigned long ulButtonPressCounts = 0UL;

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

int main(void)
{
	/* Configure the hardware ready to run the test. */
	prvSetupHardware();

	/* Start standard demo/test application flash tasks.  See the comments at
	the top of this file.  The LED flash tasks are always created.  The other
	tasks are only created if mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY is set to
	0 (at the top of this file).  See the comments at the top of this file for
	more information. */
	vStartLEDFlashTasks( mainFLASH_TASK_PRIORITY );

	/* The following function will only create more tasks and timers if
	mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY is set to 0 (at the top of this
	file).  See the comments at the top of this file for more information. */
	prvOptionallyCreateComprehensveTestApplication();

	/* Start the scheduler. */
	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 prvCheckTimerCallback( TimerHandle_t xTimer )
{
static long lChangedTimerPeriodAlready = pdFALSE;
static unsigned long ulLastRegTest1Value = 0, ulLastRegTest2Value = 0;
long lErrorFound = pdFALSE;

	/* Check all the demo tasks (other than the flash tasks) to ensure
	that they are all still running, and that none have detected an error. */

	if( xAreMathsTaskStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xAreIntegerMathsTaskStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xAreDynamicPriorityTasksStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xAreBlockingQueuesStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if ( xAreBlockTimeTestTasksStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if ( xAreGenericQueueTasksStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if ( xAreRecursiveMutexTasksStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xIsCreateTaskStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xArePollingQueuesStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	if( xAreSemaphoreTasksStillRunning() != pdTRUE )
	{
		lErrorFound = pdTRUE;
	}

	/* Check that the register test 1 task is still running. */
	if( ulLastRegTest1Value == ulRegTest1LoopCounter )
	{
		lErrorFound = pdTRUE;
	}
	ulLastRegTest1Value = ulRegTest1LoopCounter;

	/* Check that the register test 2 task is still running. */
	if( ulLastRegTest2Value == ulRegTest2LoopCounter )
	{
		lErrorFound = pdTRUE;
	}
	ulLastRegTest2Value = ulRegTest2LoopCounter;

	/* Toggle the check LED to give an indication of the system status.  If
	the LED toggles every mainCHECK_TIMER_PERIOD_MS milliseconds then
	everything is ok.  A faster toggle indicates an error. */
	vParTestToggleLED( mainCHECK_LED );

	/* Have any errors been latch in lErrorFound?  If so, shorten the
	period of the check timer to mainERROR_CHECK_TIMER_PERIOD_MS milliseconds.
	This will result in an increase in the rate at which mainCHECK_LED
	toggles. */
	if( lErrorFound != pdFALSE )
	{
		if( lChangedTimerPeriodAlready == pdFALSE )
		{
			lChangedTimerPeriodAlready = pdTRUE;

			/* This call to xTimerChangePeriod() uses a zero block time.
			Functions called from inside of a timer callback function must
			*never* attempt	to block. */
			xTimerChangePeriod( xTimer, ( mainERROR_CHECK_TIMER_PERIOD_MS ), mainDONT_BLOCK );
		}
	}
}
/*-----------------------------------------------------------*/

static void prvButtonTestTask( void *pvParameters )
{
	configASSERT( xTestSemaphore );

	/* This is the task used as an example of how to synchronise a task with
	an interrupt.  Each time the button interrupt gives the semaphore, this task
	will unblock, increment its execution counter, then return to block
	again. */

	/* Take the semaphore before started to ensure it is in the correct
	state. */
	xSemaphoreTake( xTestSemaphore, mainDONT_BLOCK );

	for( ;; )
	{
		xSemaphoreTake( xTestSemaphore, portMAX_DELAY );
		ulButtonPressCounts++;
	}
}
/*-----------------------------------------------------------*/

static void prvSetupHardware( void )
{
	/* Setup STM32 system (clock, PLL and Flash configuration) */
	SystemInit();

	/* Ensure all priority bits are assigned as preemption priority bits. */
	NVIC_PriorityGroupConfig( NVIC_PriorityGroup_4 );

	/* Setup the LED outputs. */
	vParTestInitialise();

	/* Configure the button input.  This configures the interrupt to use the
	lowest interrupt priority, so it is ok to use the ISR safe FreeRTOS API
	from the button interrupt handler. */
	STM_EVAL_PBInit( BUTTON_USER, BUTTON_MODE_EXTI );
}
/*-----------------------------------------------------------*/

void vApplicationTickHook( void )
{
	#if ( mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY == 0 )
	{
		/* Just to verify that the interrupt nesting behaves as expected,
		increment ulFPUInterruptNesting on entry, and decrement it on exit. */
		ulFPUInterruptNesting++;

		/* Fill the FPU registers with 0. */
		vRegTestClearFlopRegistersToParameterValue( 0UL );

		/* Trigger a timer 2 interrupt, which will fill the registers with a
		different value and itself trigger a timer 3 interrupt.  Note that the
		timers are not actually used.  The timer 2 and 3 interrupt vectors are
		just used for convenience. */
		NVIC_SetPendingIRQ( TIM2_IRQn );

		/* Ensure that, after returning from the nested interrupts, all the FPU
		registers contain the value to which they were set by the tick hook
		function. */
		configASSERT( ulRegTestCheckFlopRegistersContainParameterValue( 0UL ) );

		ulFPUInterruptNesting--;
	}
	#endif
}
/*-----------------------------------------------------------*/

static void prvSetupNestedFPUInterruptsTest( void )
{
NVIC_InitTypeDef NVIC_InitStructure;

	/* Enable the TIM2 interrupt in the NVIC.  The timer itself is not used,
	just its interrupt vector to force nesting from software.  TIM2 must have
	a lower priority than TIM3, and both must have priorities above
	configMAX_SYSCALL_INTERRUPT_PRIORITY. */
	NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY - 1;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init( &NVIC_InitStructure );

	/* Enable the TIM3 interrupt in the NVIC.  The timer itself is not used,
	just its interrupt vector to force nesting from software.  TIM2 must have
	a lower priority than TIM3, and both must have priorities above
	configMAX_SYSCALL_INTERRUPT_PRIORITY. */
	NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY - 2;
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_Init( &NVIC_InitStructure );
}
/*-----------------------------------------------------------*/

void TIM3_IRQHandler( void )
{
	/* Just to verify that the interrupt nesting behaves as expected, increment
	ulFPUInterruptNesting on entry, and decrement it on exit. */
	ulFPUInterruptNesting++;

	/* This is the highest priority interrupt in the chain of forced nesting
	interrupts, so latch the maximum value reached by ulFPUInterruptNesting.
	This is done purely to allow verification that the nesting depth reaches
	that intended. */
	if( ulFPUInterruptNesting > ulMaxFPUInterruptNesting )
	{
		ulMaxFPUInterruptNesting = ulFPUInterruptNesting;
	}

	/* Fill the FPU registers with 99 to overwrite the values written by
	TIM2_IRQHandler(). */
	vRegTestClearFlopRegistersToParameterValue( 99UL );

	ulFPUInterruptNesting--;
}
/*-----------------------------------------------------------*/

void TIM2_IRQHandler( void )
{
	/* Just to verify that the interrupt nesting behaves as expected, increment
	ulFPUInterruptNesting on entry, and decrement it on exit. */
	ulFPUInterruptNesting++;

	/* Fill the FPU registers with 1. */
	vRegTestClearFlopRegistersToParameterValue( 1UL );

	/* Trigger a timer 3 interrupt, which will fill the registers with a
	different value. */
	NVIC_SetPendingIRQ( TIM3_IRQn );

	/* Ensure that, after returning from the nesting interrupt, all the FPU
	registers contain the value to which they were set by this interrupt
	function. */
	configASSERT( ulRegTestCheckFlopRegistersContainParameterValue( 1UL ) );

	ulFPUInterruptNesting--;
}
/*-----------------------------------------------------------*/

static void prvOptionallyCreateComprehensveTestApplication( void )
{
	#if ( mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY == 0 )
	{
	TimerHandle_t xCheckTimer = NULL;

		/* Configure the interrupts used to test FPU registers being used from
		nested interrupts. */
		prvSetupNestedFPUInterruptsTest();

		/* Start all the other standard demo/test tasks. */
		vStartIntegerMathTasks( tskIDLE_PRIORITY );
		vStartDynamicPriorityTasks();
		vStartBlockingQueueTasks( mainBLOCK_Q_PRIORITY );
		vCreateBlockTimeTasks();
		vStartCountingSemaphoreTasks();
		vStartGenericQueueTasks( tskIDLE_PRIORITY );
		vStartRecursiveMutexTasks();
		vStartPolledQueueTasks( mainQUEUE_POLL_PRIORITY );
		vStartSemaphoreTasks( mainSEM_TEST_PRIORITY );

		/* Most importantly, start the tasks that use the FPU. */
		vStartMathTasks( mainFLOP_TASK_PRIORITY );

		/* Create the register check tasks, as described at the top of this
		file */
		xTaskCreate( vRegTest1Task, "Reg1", configMINIMAL_STACK_SIZE, ( void * ) NULL, tskIDLE_PRIORITY, NULL );
		xTaskCreate( vRegTest2Task, "Reg2", configMINIMAL_STACK_SIZE, ( void * ) NULL, tskIDLE_PRIORITY, NULL );

		/* Create the semaphore that is used to demonstrate a task being
		synchronised with an interrupt. */
		vSemaphoreCreateBinary( xTestSemaphore );

		/* Create the task that is unblocked by the demonstration interrupt. */
		xTaskCreate( prvButtonTestTask, "BtnTest", configMINIMAL_STACK_SIZE, ( void * ) NULL, tskIDLE_PRIORITY, NULL );

		/* Create the software timer that performs the 'check' functionality,
		as described at the top of this file. */
		xCheckTimer = xTimerCreate( "CheckTimer",					/* A text name, purely to help debugging. */
									( mainCHECK_TIMER_PERIOD_MS ),	/* The timer period, in this case 3000ms (3s). */
									pdTRUE,							/* This is an auto-reload timer, so xAutoReload is set to pdTRUE. */
									( void * ) 0,					/* The ID is not used, so can be set to anything. */
									prvCheckTimerCallback			/* The callback function that inspects the status of all the other tasks. */
								  );

		if( xCheckTimer != NULL )
		{
			xTimerStart( xCheckTimer, mainDONT_BLOCK );
		}

		/* This task has to be created last as it keeps account of the number of
		tasks it expects to see running. */
		vCreateSuicidalTasks( mainCREATOR_TASK_PRIORITY );
	}
	#else /* mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY */
	{
		/* Just to prevent compiler warnings when the configuration options are
		set such that these static functions are not used. */
		( void ) vRegTest1Task;
		( void ) vRegTest2Task;
		( void ) prvCheckTimerCallback;
		( void ) prvSetupNestedFPUInterruptsTest;
	}
	#endif /* mainCREATE_SIMPLE_LED_FLASHER_DEMO_ONLY */
}
/*-----------------------------------------------------------*/

void EXTI9_5_IRQHandler(void)
{
long lHigherPriorityTaskWoken = pdFALSE;

	/* Only line 6 is enabled, so there is no need to test which line generated
	the interrupt. */
	EXTI_ClearITPendingBit( EXTI_Line6 );

	/* This interrupt does nothing more than demonstrate how to synchronise a
	task with an interrupt.  First the handler releases a semaphore.
	lHigherPriorityTaskWoken has been initialised to zero. */
	xSemaphoreGiveFromISR( xTestSemaphore, &lHigherPriorityTaskWoken );

	/* If there was a task that was blocked on the semaphore, and giving the
	semaphore caused the task to unblock, and the unblocked task has a priority
	higher than the currently executing task (the task that this interrupt
	interrupted), then lHigherPriorityTaskWoken will have been set to pdTRUE.
	Passing pdTRUE into the following macro call will cause this interrupt to
	return directly to the unblocked, higher priority, task. */
	portEND_SWITCHING_ISR( lHigherPriorityTaskWoken );
}
/*-----------------------------------------------------------*/

void vApplicationMallocFailedHook( void )
{
	/* vApplicationMallocFailedHook() will only be called if
	configUSE_MALLOC_FAILED_HOOK is set to 1 in FreeRTOSConfig.h.  It is a hook
	function that will get called if a call to pvPortMalloc() fails.
	pvPortMalloc() is called internally by the kernel whenever a task, queue,
	timer or semaphore is created.  It is also called by various parts of the
	demo application.  If heap_1.c or heap_2.c are used, then the size of the
	heap available to pvPortMalloc() is defined by configTOTAL_HEAP_SIZE in
	FreeRTOSConfig.h, and the xPortGetFreeHeapSize() API function can be used
	to query the size of free heap space that remains (although it does not
	provide information on how the remaining heap might be fragmented). */
	taskDISABLE_INTERRUPTS();
	for( ;; );
}
/*-----------------------------------------------------------*/

void vApplicationIdleHook( void )
{
	/* vApplicationIdleHook() will only be called if configUSE_IDLE_HOOK is set
	to 1 in FreeRTOSConfig.h.  It will be called on each iteration of the idle
	task.  It is essential that code added to this hook function never attempts
	to block in any way (for example, call xQueueReceive() with a block time
	specified, or call vTaskDelay()).  If the application makes use of the
	vTaskDelete() API function (as this demo application does) then it is also
	important that vApplicationIdleHook() is permitted to return to its calling
	function, because it is the responsibility of the idle task to clean up
	memory allocated by the kernel to any task that has since been deleted. */
}
/*-----------------------------------------------------------*/

void vApplicationStackOverflowHook( TaskHandle_t pxTask, char *pcTaskName )
{
	( void ) pcTaskName;
	( void ) pxTask;

	/* Run time stack overflow checking is performed if
	configCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2.  This hook
	function is called if a stack overflow is detected. */
	taskDISABLE_INTERRUPTS();
	for( ;; );
}
/*-----------------------------------------------------------*/