STM32F401CCUx gets stuck with the kernel interrupt priority

mikisugi · April 22, 2021, 11:31am

Hi all,

I’m a bit new to FreeRTOS, I have used FreeRTOS on an arduino uno some years ago but can’t remember a lot from it.
I’ve got 2 PCB’s, one using the STM32F401CCUx and the other using the STM32F030C8Tx. Both with keil uvision and cmsis.

For both i created a new project the same way. (see screenshot below)

For the F0 it worked perfect, 2 simple tasks turning leds on and off.

For the F4 the same FreeRTOS code doesn’t work.
I used the debugger in uvision to try and find where it got stuck because it does compile and upload and it seems to get a hard fault in this line in the xPortStartScheduler:
/* The kernel interrupt priority should be set to the lowest priority. */
configASSERT( ucMaxPriorityValue == ( configKERNEL_INTERRUPT_PRIORITY & ucMaxPriorityValue ) );

After some looking around i found that the ucMaxPriorityValue is 0xF0 and that the configKERNEL_INTERRUPT_PRIORITY is 0xE0 which gives it the hardfault because 0xF0 is not 0xE0

I assume I’m just making a big mistake in my FreeRTOSConfig.h file, but I’m not sure.

Anyone got any tips?

RAc · April 22, 2021, 11:49am

which ports are you using for the two platforms? If everything’s right there, my guess would be KERNEL_INTERRUPT_PRORITY and MAX_SYSCALL_PRIORITY settings in freertosconfig.h.

mikisugi · April 22, 2021, 12:40pm

i’m using the port.c file from RVDS\ARM_CM4F

i can’t find the KERNEL_INTERRUPT_PRIORITY, i can only find the configKERNEL_INTERRUPT_PRIORITY which is (configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS)) and gives 0xE0

i also can’t find the MAX_SYSCALL_PRIORITY

RAc · April 22, 2021, 12:52pm

could you copy-and paste the entire contents of both freertosconfig.h to this thread?

mikisugi · April 22, 2021, 1:00pm

stm32F4:

/*
 * FreeRTOS Kernel V10.2.0
 * Copyright (C) 2019 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!
 */


#ifndef FREERTOS_CONFIG_H
#define FREERTOS_CONFIG_H

/*-----------------------------------------------------------
 * Application specific definitions.
 *
 * These definitions should be adjusted for your particular hardware and
 * application requirements.
 *
 * THESE PARAMETERS ARE DESCRIBED WITHIN THE 'CONFIGURATION' SECTION OF THE
 * FreeRTOS API DOCUMENTATION AVAILABLE ON THE FreeRTOS.org WEB SITE.
 *
 * See http://www.freertos.org/a00110.html
 *----------------------------------------------------------*/

#if (defined(__ARMCC_VERSION) || defined(__GNUC__) || defined(__ICCARM__))
#include <stdint.h>

extern uint32_t SystemCoreClock;
#endif

/* Constants that describe the hardware and memory usage. */
#define configCPU_CLOCK_HZ                    (SystemCoreClock)
#define configTICK_RATE_HZ                    ((TickType_t)1000)
#define configTOTAL_HEAP_SIZE                 ((size_t)4096)
#define configMINIMAL_STACK_SIZE              ((uint16_t)256)
#define configSUPPORT_DYNAMIC_ALLOCATION      1
#define configSUPPORT_STATIC_ALLOCATION       0

/* Constants related to the behaviour or the scheduler. */
#define configMAX_PRIORITIES                  5
#define configUSE_PREEMPTION                  1
#define configUSE_TIME_SLICING                1
#define configIDLE_SHOULD_YIELD               1
#define configMAX_TASK_NAME_LEN               (10)
#define configUSE_16_BIT_TICKS                0

/* Software timer definitions. */
#define configUSE_TIMERS                      0
#define configTIMER_TASK_PRIORITY             2
#define configTIMER_QUEUE_LENGTH              5
#define configTIMER_TASK_STACK_DEPTH          (configMINIMAL_STACK_SIZE * 2)

/* Constants that build features in or out. */
#define configUSE_MUTEXES                     1
#define configUSE_RECURSIVE_MUTEXES           1
#define configUSE_COUNTING_SEMAPHORES         1
#define configUSE_QUEUE_SETS                  1
#define configUSE_TASK_NOTIFICATIONS          1
#define configUSE_TRACE_FACILITY              1
#define configUSE_TICKLESS_IDLE               1
#define configUSE_APPLICATION_TASK_TAG        0
#define configUSE_NEWLIB_REENTRANT            0
#define configUSE_CO_ROUTINES                 0

/* Constants provided for debugging and optimisation assistance. */
#define configCHECK_FOR_STACK_OVERFLOW        0
#define configQUEUE_REGISTRY_SIZE             0
#define configASSERT( x )                     if( ( x ) == 0 ) { taskDISABLE_INTERRUPTS(); for( ;; ); }

/* Constants that define which hook (callback) functions should be used. */
#define configUSE_IDLE_HOOK                   0
#define configUSE_TICK_HOOK                   0
#define configUSE_DAEMON_TASK_STARTUP_HOOK    0
#define configUSE_MALLOC_FAILED_HOOK          0

/* Port specific configuration. */
#define configENABLE_MPU                      0
#define configENABLE_FPU                      1
#define configENABLE_TRUSTZONE                1
#define configMINIMAL_SECURE_STACK_SIZE       ((uint32_t)1024)
#define configRUN_FREERTOS_SECURE_ONLY        0

/* Cortex-M specific definitions. */
#ifdef __NVIC_PRIO_BITS
  /* __NVIC_PRIO_BITS will be specified when CMSIS is being used. */
  #define configPRIO_BITS                     __NVIC_PRIO_BITS
#else
  /* 7 priority levels */
  #define configPRIO_BITS                     3
#endif

/* The lowest interrupt priority that can be used in a call to a "set priority" function. */
#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY       0x07

/* The highest interrupt priority that can be used by any interrupt service
 * routine that makes calls to interrupt safe FreeRTOS API functions.  DO NOT
 * CALL INTERRUPT SAFE FREERTOS API FUNCTIONS FROM ANY INTERRUPT THAT HAS A
 * HIGHER PRIORITY THAN THIS! (higher priorities are lower numeric values). */
#define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY  5

/* Interrupt priorities used by the kernel port layer itself.  These are generic
 * to all Cortex-M ports, and do not rely on any particular library functions. */
#define configKERNEL_INTERRUPT_PRIORITY               (configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS))

/* !!!! configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to zero !!!!
 * See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
#define configMAX_SYSCALL_INTERRUPT_PRIORITY          (configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS))

/* Set the following definitions to 1 to include the API function, or zero
 * to exclude the API function.  NOTE:  Setting an INCLUDE_ parameter to 0 is
 * only necessary if the linker does not automatically remove functions that are
 * not referenced anyway. */
#define INCLUDE_vTaskPrioritySet              1
#define INCLUDE_uxTaskPriorityGet             1
#define INCLUDE_vTaskDelete                   1
#define INCLUDE_vTaskSuspend                  1
#define INCLUDE_vTaskDelayUntil               1
#define INCLUDE_vTaskDelay                    1
#define INCLUDE_xTaskGetIdleTaskHandle        1
#define INCLUDE_xTaskAbortDelay               1
#define INCLUDE_xQueueGetMutexHolder          1
#define INCLUDE_xSemaphoreGetMutexHolder      1
#define INCLUDE_xTaskGetHandle                1
#define INCLUDE_uxTaskGetStackHighWaterMark   1
#define INCLUDE_uxTaskGetStackHighWaterMark2  1
#define INCLUDE_eTaskGetState                 1
#define INCLUDE_xTaskResumeFromISR            1
#define INCLUDE_xTimerPendFunctionCall        1
#define INCLUDE_xTaskGetSchedulerState        1
#define INCLUDE_xTaskGetCurrentTaskHandle     1

/* Map the FreeRTOS port interrupt handlers to their CMSIS standard names. */
#define xPortPendSVHandler                    PendSV_Handler
#define vPortSVCHandler                       SVC_Handler
#define xPortSysTickHandler                   SysTick_Handler

#if (defined(__ARMCC_VERSION) || defined(__GNUC__) || defined(__ICCARM__))
/* Include debug event definitions */
#include "freertos_evr.h"
#endif

#endif /* FREERTOS_CONFIG_H */

stm32F0

/*
 * FreeRTOS Kernel V10.2.0
 * Copyright (C) 2019 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!
 */


#ifndef FREERTOS_CONFIG_H
#define FREERTOS_CONFIG_H

/*-----------------------------------------------------------
 * Application specific definitions.
 *
 * These definitions should be adjusted for your particular hardware and
 * application requirements.
 *
 * THESE PARAMETERS ARE DESCRIBED WITHIN THE 'CONFIGURATION' SECTION OF THE
 * FreeRTOS API DOCUMENTATION AVAILABLE ON THE FreeRTOS.org WEB SITE.
 *
 * See http://www.freertos.org/a00110.html
 *----------------------------------------------------------*/

#if (defined(__ARMCC_VERSION) || defined(__GNUC__) || defined(__ICCARM__))
#include <stdint.h>

extern uint32_t SystemCoreClock;
#endif

/* Constants that describe the hardware and memory usage. */
#define configCPU_CLOCK_HZ                    (SystemCoreClock)
#define configTICK_RATE_HZ                    ((TickType_t)1000)
#define configTOTAL_HEAP_SIZE                 ((size_t)4096)
#define configMINIMAL_STACK_SIZE              ((uint16_t)256)
#define configSUPPORT_DYNAMIC_ALLOCATION      1
#define configSUPPORT_STATIC_ALLOCATION       0

/* Constants related to the behaviour or the scheduler. */
#define configMAX_PRIORITIES                  5
#define configUSE_PREEMPTION                  1
#define configUSE_TIME_SLICING                1
#define configIDLE_SHOULD_YIELD               1
#define configMAX_TASK_NAME_LEN               (10)
#define configUSE_16_BIT_TICKS                0

/* Software timer definitions. */
#define configUSE_TIMERS                      0
#define configTIMER_TASK_PRIORITY             2
#define configTIMER_QUEUE_LENGTH              5
#define configTIMER_TASK_STACK_DEPTH          (configMINIMAL_STACK_SIZE * 2)

/* Constants that build features in or out. */
#define configUSE_MUTEXES                     1
#define configUSE_RECURSIVE_MUTEXES           1
#define configUSE_COUNTING_SEMAPHORES         1
#define configUSE_QUEUE_SETS                  1
#define configUSE_TASK_NOTIFICATIONS          1
#define configUSE_TRACE_FACILITY              1
#define configUSE_TICKLESS_IDLE               1
#define configUSE_APPLICATION_TASK_TAG        0
#define configUSE_NEWLIB_REENTRANT            0
#define configUSE_CO_ROUTINES                 0

/* Constants provided for debugging and optimisation assistance. */
#define configCHECK_FOR_STACK_OVERFLOW        0
#define configQUEUE_REGISTRY_SIZE             0
#define configASSERT( x )                     if( ( x ) == 0 ) { taskDISABLE_INTERRUPTS(); for( ;; ); }

/* Constants that define which hook (callback) functions should be used. */
#define configUSE_IDLE_HOOK                   0
#define configUSE_TICK_HOOK                   0
#define configUSE_DAEMON_TASK_STARTUP_HOOK    0
#define configUSE_MALLOC_FAILED_HOOK          0

/* Port specific configuration. */
#define configENABLE_MPU                      0
#define configENABLE_FPU                      1
#define configENABLE_TRUSTZONE                1
#define configMINIMAL_SECURE_STACK_SIZE       ((uint32_t)1024)
#define configRUN_FREERTOS_SECURE_ONLY        0

/* Cortex-M specific definitions. */
#ifdef __NVIC_PRIO_BITS
  /* __NVIC_PRIO_BITS will be specified when CMSIS is being used. */
  #define configPRIO_BITS                     __NVIC_PRIO_BITS
#else
  /* 7 priority levels */
  //#define configPRIO_BITS                     3
  #define configPRIO_BITS                     4
#endif

/* The lowest interrupt priority that can be used in a call to a "set priority" function. */
//#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY       0x07
#define configLIBRARY_LOWEST_INTERRUPT_PRIORITY       0x0F

/* The highest interrupt priority that can be used by any interrupt service
 * routine that makes calls to interrupt safe FreeRTOS API functions.  DO NOT
 * CALL INTERRUPT SAFE FREERTOS API FUNCTIONS FROM ANY INTERRUPT THAT HAS A
 * HIGHER PRIORITY THAN THIS! (higher priorities are lower numeric values). */
#define configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY  5

/* Interrupt priorities used by the kernel port layer itself.  These are generic
 * to all Cortex-M ports, and do not rely on any particular library functions. */
#define configKERNEL_INTERRUPT_PRIORITY               (configLIBRARY_LOWEST_INTERRUPT_PRIORITY << (8 - configPRIO_BITS))

/* !!!! configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to zero !!!!
 * See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
#define configMAX_SYSCALL_INTERRUPT_PRIORITY          (configLIBRARY_MAX_SYSCALL_INTERRUPT_PRIORITY << (8 - configPRIO_BITS))

/* Set the following definitions to 1 to include the API function, or zero
 * to exclude the API function.  NOTE:  Setting an INCLUDE_ parameter to 0 is
 * only necessary if the linker does not automatically remove functions that are
 * not referenced anyway. */
#define INCLUDE_vTaskPrioritySet              1
#define INCLUDE_uxTaskPriorityGet             1
#define INCLUDE_vTaskDelete                   1
#define INCLUDE_vTaskSuspend                  1
#define INCLUDE_vTaskDelayUntil               1
#define INCLUDE_vTaskDelay                    1
#define INCLUDE_xTaskGetIdleTaskHandle        1
#define INCLUDE_xTaskAbortDelay               1
#define INCLUDE_xQueueGetMutexHolder          1
#define INCLUDE_xSemaphoreGetMutexHolder      1
#define INCLUDE_xTaskGetHandle                1
#define INCLUDE_uxTaskGetStackHighWaterMark   1
#define INCLUDE_uxTaskGetStackHighWaterMark2  1
#define INCLUDE_eTaskGetState                 1
#define INCLUDE_xTaskResumeFromISR            1
#define INCLUDE_xTimerPendFunctionCall        1
#define INCLUDE_xTaskGetSchedulerState        1
#define INCLUDE_xTaskGetCurrentTaskHandle     1

/* Map the FreeRTOS port interrupt handlers to their CMSIS standard names. */
#define xPortPendSVHandler                    PendSV_Handler
#define vPortSVCHandler                       SVC_Handler
#define xPortSysTickHandler                   SysTick_Handler

#if (defined(__ARMCC_VERSION) || defined(__GNUC__) || defined(__ICCARM__))
/* Include debug event definitions */
#include "freertos_evr.h"
#endif

#endif /* FREERTOS_CONFIG_H */

RAc · April 22, 2021, 1:07pm

I believe you need to set this to 4 on the M4 as well.

mikisugi · April 22, 2021, 1:12pm

it didn’t solve it.
could you explain why?

mikisugi · April 22, 2021, 1:14pm

after also changing the configLIBRARY_LOWEST_INTERRUPT_PRIORITY to 0x0F it did work, but i’m wondering what the thought behind it is

RAc · April 22, 2021, 1:15pm

well, I looked at the tech ref manual of the stm32f401, and it lists 16 interrupt priorities which would imply 4 bits. The assert error message you indicated also hints at something wrong with the interrupt level.

Edit: Ok, that makes sense then. Sorry I didn’t mention the other one right along. The scheduler must run at lowest priority.

Is it solved then?

mikisugi · April 22, 2021, 1:23pm

yes it works now, just for my understanding

so the configPRIO_BITS had to be raised because the M4 that I have is using 16 interrupts which is 4 bits

and the configLIBRARY_LOWEST_INTERRUPT_PRIORITY needed to be 0x0F because we have 4 bits interrupts (which is hexadecimal 0x0F)?

thanks for the help RAc

richard-damon · April 22, 2021, 1:37pm

The number of interrupts and the number of priorities are not related. Your processor actually has WAY more than 16 interrupts, most stm32 parts have over a hundred different interrupts available. It has 16 interrupt PRIORITIES.

The confusion comes in that the priority register is an 8 bit register, and depending on the part, only some of the bits are used. You can think of the priority either as the value of that register, or the value of the used bits, shifted down to the base of the word. Because people tend to think of priorities as small consecutive numbers, that later is how most subroutine that work with priorities due it for that API. Typically, that means interrupt priorities are a number 0 to 15.

Then you get the issue that small numbers mean HIGHER priority, The machine will go to priority #1 before priority #15, so higher means smaller.

mikisugi · April 22, 2021, 2:07pm

loud and clear, thank you very much.

btw, do i need to close the topic somewhere?

RAc · April 22, 2021, 2:27pm

just mark the post in this thread that you believed solved the problem as the “solution.”

mikisugi · April 23, 2021, 11:16am

So I thought it was fixed, but today i found out that it isn’t.
an hour after i had changed the configPRIO_BITS from 3 to 4 and the configLIBRARY_LOWEST_INTERRUPT_PRIORITY from 0x07 to 0x0F i started getting problems uvision saying “cannot write to ram for flash algorithms!”. this only happens if i try uploading a program with 4 and 0x0F to a board where it already has 4 and 0x0F. if i try uploading 4 and 0x0F to a board containing 3 and 0x07 then it does work.
making the 2 tasks that i have run less frequent makes the error also appear less often.

is this a priority issue where me trying to upload a program to the plc doesn’t get the highest priority?

rtel · April 23, 2021, 2:48pm

I’ve not read this whole thread so may be way off the mark, but “cannot write ram for flash algorithms” sounds like you are having an issue while programming the executable to flash, so before the executable has even run. I can’t see how the change you describe can be responsible for that unless you have already programmed and executed it at least once already - and the execution has done something that prevents the debugger from taking back control of the device. If that is the case then take a look at how the debugger is set up to reset the device - there are normally options, such as “hardware reset” as opposed to other forms of reset, and other options such as “vector catch” that you need to have set correctly for the debugger to force control over the device.

RAc · April 26, 2021, 7:34am

Hi mikisugi,

Have you made any progress here? I believe Richard is spot on with his analysis; in looking at your target firmware instead of your toolchain, you are barking up the wrong tree.

There is a simple test you can make: Power cycle (hard reset) your target and debug probe prior to downloading. If the download works after that, it’s definitely a problem with your debugger/probe not resetting the target correctly, as Richard suggested.