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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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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.
>>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
distribute a combined work that includes FreeRTOS without being obliged to
provide the source code for proprietary components outside of the FreeRTOS
FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details. You should have received a copy of the GNU General Public License
and the FreeRTOS license exception along with FreeRTOS; if not it can be
viewed here: and also obtained by
writing to Real Time Engineers Ltd., contact details for whom are available
on the FreeRTOS WEB site.
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*************************************************************************** - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details. - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, and our new
fully thread aware and reentrant UDP/IP stack. - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems, who sell the code with commercial support,
indemnification and middleware, under the OpenRTOS brand. - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
* This project provides two demo applications. A simple blinky style project,
* and a more comprehensive test and demo application. The
* mainCREATE_SIMPLE_BLINKY_DEMO_ONLY setting (defined in this file) is used to
* select between the two. The simply blinky demo is implemented and described
* in main_blinky.c. The more comprehensive test and demo application is
* implemented and described in main_full.c.
* This file implements the code that is not demo specific, including the
* hardware setup and FreeRTOS hook functions. It also contains a dummy
* interrupt service routine called Dummy_IRQHandler() that is provided as an
* example of how to use interrupt safe FreeRTOS API functions (those that end
* in "FromISR").
/* Standard includes. */
#include "string.h"
/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Hardware specific includes. */
#include "lpc11xx.h"
/* Set mainCREATE_SIMPLE_BLINKY_DEMO_ONLY to one to run the simple blinky demo,
or 0 to run the more comprehensive test and demo application. */
/* The bit on port 0 to which the LED is wired. */
#define mainLED_BIT ( 1UL << 7UL )
/* The configCHECK_FOR_STACK_OVERFLOW setting in FreeRTOSConifg can be used to
check task stacks for overflows. It does not however check the stack used by
interrupts. This demo has a simple addition that will also check the stack used
by interrupts if mainCHECK_INTERRUPT_STACK is set to 1. Note that this check is
only performed from the tick hook function (which runs in an interrupt context).
It is a good debugging aid - but won't catch interrupt stack problems until the
tick interrupt next executes. */
const unsigned char ucExpectedInterruptStackValues[] = { 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC };
* Perform any application specific hardware configuration. The clocks,
* memory, etc. are configured before main() is called.
static void prvSetupHardware( void );
* The hardware only has a single LED. Simply toggle it.
void vMainToggleLED( void );
/* main_blinky() is used when mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 1.
main_full() is used when mainCREATE_SIMPLE_BLINKY_DEMO_ONLY is set to 0. */
void main_blinky( void );
void main_full( void );
/* The GPIO port to which the LED is attached. */
static LPC_GPIO_TypeDef * const xGPIO0 = LPC_GPIO0;
int main( void )
/* Prepare the hardware to run this demo. */
/* The mainCREATE_SIMPLE_BLINKY_DEMO_ONLY setting is described at the top
of this file. */
return 0;
void vMainToggleLED( void )
static unsigned long ulLEDState = 0UL;
if( ulLEDState == 0UL )
ulLEDState = !ulLEDState;
static void prvSetupHardware( void )
extern unsigned long _vStackTop[], _pvHeapStart[];
unsigned long ulInterruptStackSize;
/* Enable AHB clock for GPIO. */
/* Configure GPIO for LED output. */
xGPIO0->DIR |= mainLED_BIT;
/* The size of the stack used by main and interrupts is not defined in
the linker, but just uses whatever RAM is left. Calculate the amount of
RAM available for the main/interrupt/system stack, and check it against
a reasonable number. If this assert is hit then it is likely you don't
have enough stack to start the kernel, or to allow interrupts to nest.
Note - this is separate to the stacks that are used by tasks. The stacks
that are used by tasks are automatically checked if
configCHECK_FOR_STACK_OVERFLOW is not 0 in FreeRTOSConfig.h - but the stack
used by interrupts is not. Reducing the conifgTOTAL_HEAP_SIZE setting will
increase the stack available to main() and interrupts. */
ulInterruptStackSize = ( ( unsigned long ) _vStackTop ) - ( ( unsigned long ) _pvHeapStart );
configASSERT( ulInterruptStackSize > 350UL );
/* Fill the stack used by main() and interrupts to a known value, so its
use can be manually checked. */
memcpy( ( void * ) _pvHeapStart, ucExpectedInterruptStackValues, sizeof( ucExpectedInterruptStackValues ) );
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). */
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( xTaskHandle pxTask, signed 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. */
for( ;; );
void vApplicationTickHook( void )
extern unsigned long _pvHeapStart[];
/* This function will be called by each tick interrupt if
configUSE_TICK_HOOK is set to 1 in FreeRTOSConfig.h. User code can be
added here, but the tick hook is called from an interrupt context, so
code must not attempt to block, and only the interrupt safe FreeRTOS API
functions can be used (those that end in FromISR()). */
/* Manually check the last few bytes of the interrupt stack to check they
have not been overwritten. Note - the task stacks are automatically
checked for overflow if configCHECK_FOR_STACK_OVERFLOW is set to 1 or 2
in FreeRTOSConifg.h, but the interrupt stack is not. */
configASSERT( memcmp( ( void * ) _pvHeapStart, ucExpectedInterruptStackValues, sizeof( ucExpectedInterruptStackValues ) ) == 0U );
#endif /* mainCHECK_INTERRUPT_STACK */
void Dummy_IRQHandler(void)
long lHigherPriorityTaskWoken = pdFALSE;
/* Clear the interrupt if necessary. */
/* This interrupt does nothing more than demonstrate how to synchronise a
task with an interrupt. A semaphore is used for this purpose. Note
lHigherPriorityTaskWoken is initialised to zero. Only FreeRTOS API functions
that end in "FromISR" can be called from an ISR. */
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 current Running state task (the task that this interrupt
interrupted), then lHigherPriorityTaskWoken will have been set to pdTRUE
internally within xSemaphoreGiveFromISR(). Passing pdTRUE into the
portEND_SWITCHING_ISR() macro will result in a context switch being pended to
ensure this interrupt returns directly to the unblocked, higher priority,
task. Passing pdFALSE into portEND_SWITCHING_ISR() has no effect. */
portEND_SWITCHING_ISR( lHigherPriorityTaskWoken );
#endif /* JUST_AN_EXAMPLE_ISR */