diff options
Diffstat (limited to 'rtos/FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c')
| -rw-r--r-- | rtos/FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c | 639 |
1 files changed, 639 insertions, 0 deletions
diff --git a/rtos/FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c b/rtos/FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c new file mode 100644 index 0000000..e78573a --- /dev/null +++ b/rtos/FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c @@ -0,0 +1,639 @@ +/* + FreeRTOS V8.0.0 - Copyright (C) 2014 Real Time Engineers Ltd. + All rights reserved + + VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. + + *************************************************************************** + * * + * FreeRTOS provides completely free yet professionally developed, * + * robust, strictly quality controlled, supported, and cross * + * platform software that has become a de facto standard. * + * * + * Help yourself get started quickly and support the FreeRTOS * + * project by purchasing a FreeRTOS tutorial book, reference * + * manual, or both from: http://www.FreeRTOS.org/Documentation * + * * + * Thank you! * + * * + *************************************************************************** + + 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 + >>! kernel. + + 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. Full license text is available from the following + link: http://www.freertos.org/a00114.html + + 1 tab == 4 spaces! + + *************************************************************************** + * * + * Having a problem? Start by reading the FAQ "My application does * + * not run, what could be wrong?" * + * * + * http://www.FreeRTOS.org/FAQHelp.html * + * * + *************************************************************************** + + http://www.FreeRTOS.org - Documentation, books, training, latest versions, + license and Real Time Engineers Ltd. contact details. + + http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, + including FreeRTOS+Trace - an indispensable productivity tool, a DOS + compatible FAT file system, and our tiny thread aware UDP/IP stack. + + http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High + Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS + licenses offer ticketed support, indemnification and middleware. + + http://www.SafeRTOS.com - 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. + + 1 tab == 4 spaces! +*/ + +/*----------------------------------------------------------- + * Implementation of functions defined in portable.h for the ARM CM4F port. + *----------------------------------------------------------*/ + +/* Compiler includes. */ +#include <intrinsics.h> + +/* Scheduler includes. */ +#include "FreeRTOS.h" +#include "task.h" + +#ifndef __ARMVFP__ + #error This port can only be used when the project options are configured to enable hardware floating point support. +#endif + +#if configMAX_SYSCALL_INTERRUPT_PRIORITY == 0 + #error configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html +#endif + +#ifndef configSYSTICK_CLOCK_HZ + #define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ + /* Ensure the SysTick is clocked at the same frequency as the core. */ + #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) +#else + /* The way the SysTick is clocked is not modified in case it is not the same + as the core. */ + #define portNVIC_SYSTICK_CLK_BIT ( 0 ) +#endif + +/* Constants required to manipulate the core. Registers first... */ +#define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000e010 ) ) +#define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile uint32_t * ) 0xe000e014 ) ) +#define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile uint32_t * ) 0xe000e018 ) ) +#define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t * ) 0xe000ed20 ) ) +/* ...then bits in the registers. */ +#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) +#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) +#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) +#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) +#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) + +#define portNVIC_PENDSV_PRI ( ( ( uint32_t ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL ) +#define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL ) + +/* Constants required to check the validity of an interrupt priority. */ +#define portFIRST_USER_INTERRUPT_NUMBER ( 16 ) +#define portNVIC_IP_REGISTERS_OFFSET_16 ( 0xE000E3F0 ) +#define portAIRCR_REG ( * ( ( volatile uint32_t * ) 0xE000ED0C ) ) +#define portMAX_8_BIT_VALUE ( ( uint8_t ) 0xff ) +#define portTOP_BIT_OF_BYTE ( ( uint8_t ) 0x80 ) +#define portMAX_PRIGROUP_BITS ( ( uint8_t ) 7 ) +#define portPRIORITY_GROUP_MASK ( 0x07UL << 8UL ) +#define portPRIGROUP_SHIFT ( 8UL ) + +/* Constants required to manipulate the VFP. */ +#define portFPCCR ( ( volatile uint32_t * ) 0xe000ef34 ) /* Floating point context control register. */ +#define portASPEN_AND_LSPEN_BITS ( 0x3UL << 30UL ) + +/* Constants required to set up the initial stack. */ +#define portINITIAL_XPSR ( 0x01000000 ) +#define portINITIAL_EXEC_RETURN ( 0xfffffffd ) + +/* The systick is a 24-bit counter. */ +#define portMAX_24_BIT_NUMBER ( 0xffffffUL ) + +/* A fiddle factor to estimate the number of SysTick counts that would have +occurred while the SysTick counter is stopped during tickless idle +calculations. */ +#define portMISSED_COUNTS_FACTOR ( 45UL ) + + +/* Each task maintains its own interrupt status in the critical nesting +variable. */ +static UBaseType_t uxCriticalNesting = 0xaaaaaaaa; + +/* + * Setup the timer to generate the tick interrupts. The implementation in this + * file is weak to allow application writers to change the timer used to + * generate the tick interrupt. + */ +void vPortSetupTimerInterrupt( void ); + +/* + * Exception handlers. + */ +void xPortSysTickHandler( void ); + +/* + * Start first task is a separate function so it can be tested in isolation. + */ +extern void vPortStartFirstTask( void ); + +/* + * Turn the VFP on. + */ +extern void vPortEnableVFP( void ); + +/* + * Used to catch tasks that attempt to return from their implementing function. + */ +static void prvTaskExitError( void ); + +/*-----------------------------------------------------------*/ + +/* + * The number of SysTick increments that make up one tick period. + */ +#if configUSE_TICKLESS_IDLE == 1 + static uint32_t ulTimerCountsForOneTick = 0; +#endif /* configUSE_TICKLESS_IDLE */ + +/* + * The maximum number of tick periods that can be suppressed is limited by the + * 24 bit resolution of the SysTick timer. + */ +#if configUSE_TICKLESS_IDLE == 1 + static uint32_t xMaximumPossibleSuppressedTicks = 0; +#endif /* configUSE_TICKLESS_IDLE */ + +/* + * Compensate for the CPU cycles that pass while the SysTick is stopped (low + * power functionality only. + */ +#if configUSE_TICKLESS_IDLE == 1 + static uint32_t ulStoppedTimerCompensation = 0; +#endif /* configUSE_TICKLESS_IDLE */ + +/* + * Used by the portASSERT_IF_INTERRUPT_PRIORITY_INVALID() macro to ensure + * FreeRTOS API functions are not called from interrupts that have been assigned + * a priority above configMAX_SYSCALL_INTERRUPT_PRIORITY. + */ +#if ( configASSERT_DEFINED == 1 ) + static uint8_t ucMaxSysCallPriority = 0; + static uint32_t ulMaxPRIGROUPValue = 0; + static const volatile uint8_t * const pcInterruptPriorityRegisters = ( const volatile uint8_t * const ) portNVIC_IP_REGISTERS_OFFSET_16; +#endif /* configASSERT_DEFINED */ + +/*-----------------------------------------------------------*/ + +/* + * See header file for description. + */ +StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters ) +{ + /* Simulate the stack frame as it would be created by a context switch + interrupt. */ + + /* Offset added to account for the way the MCU uses the stack on entry/exit + of interrupts, and to ensure alignment. */ + pxTopOfStack--; + + *pxTopOfStack = portINITIAL_XPSR; /* xPSR */ + pxTopOfStack--; + *pxTopOfStack = ( StackType_t ) pxCode; /* PC */ + pxTopOfStack--; + *pxTopOfStack = ( StackType_t ) prvTaskExitError; /* LR */ + + /* Save code space by skipping register initialisation. */ + pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ + *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */ + + /* A save method is being used that requires each task to maintain its + own exec return value. */ + pxTopOfStack--; + *pxTopOfStack = portINITIAL_EXEC_RETURN; + + pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */ + + return pxTopOfStack; +} +/*-----------------------------------------------------------*/ + +static void prvTaskExitError( void ) +{ + /* A function that implements a task must not exit or attempt to return to + its caller as there is nothing to return to. If a task wants to exit it + should instead call vTaskDelete( NULL ). + + Artificially force an assert() to be triggered if configASSERT() is + defined, then stop here so application writers can catch the error. */ + configASSERT( uxCriticalNesting == ~0UL ); + portDISABLE_INTERRUPTS(); + for( ;; ); +} +/*-----------------------------------------------------------*/ + +/* + * See header file for description. + */ +BaseType_t xPortStartScheduler( void ) +{ + #if( configASSERT_DEFINED == 1 ) + { + volatile uint32_t ulOriginalPriority; + volatile uint8_t * const pucFirstUserPriorityRegister = ( volatile uint8_t * const ) ( portNVIC_IP_REGISTERS_OFFSET_16 + portFIRST_USER_INTERRUPT_NUMBER ); + volatile uint8_t ucMaxPriorityValue; + + /* Determine the maximum priority from which ISR safe FreeRTOS API + functions can be called. ISR safe functions are those that end in + "FromISR". FreeRTOS maintains separate thread and ISR API functions to + ensure interrupt entry is as fast and simple as possible. + + Save the interrupt priority value that is about to be clobbered. */ + ulOriginalPriority = *pucFirstUserPriorityRegister; + + /* Determine the number of priority bits available. First write to all + possible bits. */ + *pucFirstUserPriorityRegister = portMAX_8_BIT_VALUE; + + /* Read the value back to see how many bits stuck. */ + ucMaxPriorityValue = *pucFirstUserPriorityRegister; + + /* Use the same mask on the maximum system call priority. */ + ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue; + + /* Calculate the maximum acceptable priority group value for the number + of bits read back. */ + ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS; + while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE ) + { + ulMaxPRIGROUPValue--; + ucMaxPriorityValue <<= ( uint8_t ) 0x01; + } + + /* Shift the priority group value back to its position within the AIRCR + register. */ + ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT; + ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK; + + /* Restore the clobbered interrupt priority register to its original + value. */ + *pucFirstUserPriorityRegister = ulOriginalPriority; + } + #endif /* conifgASSERT_DEFINED */ + + /* Make PendSV and SysTick the lowest priority interrupts. */ + portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; + portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; + + /* Start the timer that generates the tick ISR. Interrupts are disabled + here already. */ + vPortSetupTimerInterrupt(); + + /* Initialise the critical nesting count ready for the first task. */ + uxCriticalNesting = 0; + + /* Ensure the VFP is enabled - it should be anyway. */ + vPortEnableVFP(); + + /* Lazy save always. */ + *( portFPCCR ) |= portASPEN_AND_LSPEN_BITS; + + /* Start the first task. */ + vPortStartFirstTask(); + + /* Should not get here! */ + return 0; +} +/*-----------------------------------------------------------*/ + +void vPortEndScheduler( void ) +{ + /* Not implemented in ports where there is nothing to return to. + Artificially force an assert. */ + configASSERT( uxCriticalNesting == 1000UL ); +} +/*-----------------------------------------------------------*/ + +void vPortYield( void ) +{ + /* Set a PendSV to request a context switch. */ + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; + + /* Barriers are normally not required but do ensure the code is completely + within the specified behaviour for the architecture. */ + __DSB(); + __ISB(); +} +/*-----------------------------------------------------------*/ + +void vPortEnterCritical( void ) +{ + portDISABLE_INTERRUPTS(); + uxCriticalNesting++; + __DSB(); + __ISB(); +} +/*-----------------------------------------------------------*/ + +void vPortExitCritical( void ) +{ + configASSERT( uxCriticalNesting ); + uxCriticalNesting--; + if( uxCriticalNesting == 0 ) + { + portENABLE_INTERRUPTS(); + } +} +/*-----------------------------------------------------------*/ + +void xPortSysTickHandler( void ) +{ + /* The SysTick runs at the lowest interrupt priority, so when this interrupt + executes all interrupts must be unmasked. There is therefore no need to + save and then restore the interrupt mask value as its value is already + known. */ + ( void ) portSET_INTERRUPT_MASK_FROM_ISR(); + { + /* Increment the RTOS tick. */ + if( xTaskIncrementTick() != pdFALSE ) + { + /* A context switch is required. Context switching is performed in + the PendSV interrupt. Pend the PendSV interrupt. */ + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; + } + } + portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 ); +} +/*-----------------------------------------------------------*/ + +#if configUSE_TICKLESS_IDLE == 1 + + __weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ) + { + uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements, ulSysTickCTRL; + TickType_t xModifiableIdleTime; + + /* Make sure the SysTick reload value does not overflow the counter. */ + if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks ) + { + xExpectedIdleTime = xMaximumPossibleSuppressedTicks; + } + + /* Stop the SysTick momentarily. The time the SysTick is stopped for + is accounted for as best it can be, but using the tickless mode will + inevitably result in some tiny drift of the time maintained by the + kernel with respect to calendar time. */ + portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT; + + /* Calculate the reload value required to wait xExpectedIdleTime + tick periods. -1 is used because this code will execute part way + through one of the tick periods. */ + ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) ); + if( ulReloadValue > ulStoppedTimerCompensation ) + { + ulReloadValue -= ulStoppedTimerCompensation; + } + + /* Enter a critical section but don't use the taskENTER_CRITICAL() + method as that will mask interrupts that should exit sleep mode. */ + __disable_interrupt(); + + /* If a context switch is pending or a task is waiting for the scheduler + to be unsuspended then abandon the low power entry. */ + if( eTaskConfirmSleepModeStatus() == eAbortSleep ) + { + /* Restart from whatever is left in the count register to complete + this tick period. */ + portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG; + + /* Restart SysTick. */ + portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; + + /* Reset the reload register to the value required for normal tick + periods. */ + portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL; + + /* Re-enable interrupts - see comments above __disable_interrupt() + call above. */ + __enable_interrupt(); + } + else + { + /* Set the new reload value. */ + portNVIC_SYSTICK_LOAD_REG = ulReloadValue; + + /* Clear the SysTick count flag and set the count value back to + zero. */ + portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; + + /* Restart SysTick. */ + portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; + + /* Sleep until something happens. configPRE_SLEEP_PROCESSING() can + set its parameter to 0 to indicate that its implementation contains + its own wait for interrupt or wait for event instruction, and so wfi + should not be executed again. However, the original expected idle + time variable must remain unmodified, so a copy is taken. */ + xModifiableIdleTime = xExpectedIdleTime; + configPRE_SLEEP_PROCESSING( xModifiableIdleTime ); + if( xModifiableIdleTime > 0 ) + { + __DSB(); + __WFI(); + __ISB(); + } + configPOST_SLEEP_PROCESSING( xExpectedIdleTime ); + + /* Stop SysTick. Again, the time the SysTick is stopped for is + accounted for as best it can be, but using the tickless mode will + inevitably result in some tiny drift of the time maintained by the + kernel with respect to calendar time. */ + ulSysTickCTRL = portNVIC_SYSTICK_CTRL_REG; + portNVIC_SYSTICK_CTRL_REG = ( ulSysTickCTRL & ~portNVIC_SYSTICK_ENABLE_BIT ); + + /* Re-enable interrupts - see comments above __disable_interrupt() + call above. */ + __enable_interrupt(); + + if( ( ulSysTickCTRL & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) + { + uint32_t ulCalculatedLoadValue; + + /* The tick interrupt has already executed, and the SysTick + count reloaded with ulReloadValue. Reset the + portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick + period. */ + ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); + + /* Don't allow a tiny value, or values that have somehow + underflowed because the post sleep hook did something + that took too long. */ + if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) ) + { + ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ); + } + + portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue; + + /* The tick interrupt handler will already have pended the tick + processing in the kernel. As the pending tick will be + processed as soon as this function exits, the tick value + maintained by the tick is stepped forward by one less than the + time spent waiting. */ + ulCompleteTickPeriods = xExpectedIdleTime - 1UL; + } + else + { + /* Something other than the tick interrupt ended the sleep. + Work out how long the sleep lasted rounded to complete tick + periods (not the ulReload value which accounted for part + ticks). */ + ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; + + /* How many complete tick periods passed while the processor + was waiting? */ + ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick; + + /* The reload value is set to whatever fraction of a single tick + period remains. */ + portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements; + } + + /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG + again, then set portNVIC_SYSTICK_LOAD_REG back to its standard + value. The critical section is used to ensure the tick interrupt + can only execute once in the case that the reload register is near + zero. */ + portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; + portENTER_CRITICAL(); + { + portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; + vTaskStepTick( ulCompleteTickPeriods ); + portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL; + } + portEXIT_CRITICAL(); + } + } + +#endif /* #if configUSE_TICKLESS_IDLE */ +/*-----------------------------------------------------------*/ + +/* + * Setup the systick timer to generate the tick interrupts at the required + * frequency. + */ +__weak void vPortSetupTimerInterrupt( void ) +{ + /* Calculate the constants required to configure the tick interrupt. */ + #if configUSE_TICKLESS_IDLE == 1 + { + ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ); + xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick; + ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); + } + #endif /* configUSE_TICKLESS_IDLE */ + + /* Configure SysTick to interrupt at the requested rate. */ + portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; + portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT ); +} +/*-----------------------------------------------------------*/ + +#if( configASSERT_DEFINED == 1 ) + + void vPortValidateInterruptPriority( void ) + { + uint32_t ulCurrentInterrupt; + uint8_t ucCurrentPriority; + + /* Obtain the number of the currently executing interrupt. */ + __asm volatile( "mrs %0, ipsr" : "=r"( ulCurrentInterrupt ) ); + + /* Is the interrupt number a user defined interrupt? */ + if( ulCurrentInterrupt >= portFIRST_USER_INTERRUPT_NUMBER ) + { + /* Look up the interrupt's priority. */ + ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ]; + + /* The following assertion will fail if a service routine (ISR) for + an interrupt that has been assigned a priority above + configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API + function. ISR safe FreeRTOS API functions must *only* be called + from interrupts that have been assigned a priority at or below + configMAX_SYSCALL_INTERRUPT_PRIORITY. + + Numerically low interrupt priority numbers represent logically high + interrupt priorities, therefore the priority of the interrupt must + be set to a value equal to or numerically *higher* than + configMAX_SYSCALL_INTERRUPT_PRIORITY. + + Interrupts that use the FreeRTOS API must not be left at their + default priority of zero as that is the highest possible priority, + which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY, + and therefore also guaranteed to be invalid. + + FreeRTOS maintains separate thread and ISR API functions to ensure + interrupt entry is as fast and simple as possible. + + The following links provide detailed information: + http://www.freertos.org/RTOS-Cortex-M3-M4.html + http://www.freertos.org/FAQHelp.html */ + configASSERT( ucCurrentPriority >= ucMaxSysCallPriority ); + } + + /* Priority grouping: The interrupt controller (NVIC) allows the bits + that define each interrupt's priority to be split between bits that + define the interrupt's pre-emption priority bits and bits that define + the interrupt's sub-priority. For simplicity all bits must be defined + to be pre-emption priority bits. The following assertion will fail if + this is not the case (if some bits represent a sub-priority). + + If the application only uses CMSIS libraries for interrupt + configuration then the correct setting can be achieved on all Cortex-M + devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the + scheduler. Note however that some vendor specific peripheral libraries + assume a non-zero priority group setting, in which cases using a value + of zero will result in unpredicable behaviour. */ + configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue ); + } + +#endif /* configASSERT_DEFINED */ + + + + + + + + + + + + + + + + + + + + + |