Hi, I use CubeMX from ST with FreeRTOS version 10.0.1. I use pvPortMalloc and free in my code and sometimes it seems like the allocted memory will get corrupted. I chose heap4. Now I am confused about memory allocation: In Cube I can chose mem allocation as Dynamic, Static or mixed – do not exactly understand it. Allocation for tasks I chose Static because I want to know the size of my code in RAM at link time, rather then run-time. But then I would like to know If I call pvPortMalloc() in TaskA – where it takes the mem? Does it take space from Task_A Stack? Thanky you for explaining. Best Regards Jan.

Like the standard C library malloc() function, pvPortMalloc() always allocated memory from the heap – provided the heap has enough free memory for the allocation to complete. How the heap is allocated depends on whether you are building heap1, heap2, heap3, heap4 or heap_5: https://www.freertos.org/a00111.html

Thank you. Now I have 3 static allocated tasks – altogether they have 9216 B. Also had FreeRTOS timer with 400 B and 3 queues – 888 B. Total sum is 10504 Bytes. It means the value of TOTALHEAPSIZE should be set above this value is not it? For example if I set HEAP SIZE to 12000 B, then there is about 12000-10504 = 1496 Bytes for pvPortMalloc allocation? But: I do not understand why is possible in CubeMX to set Total Heap Size only on 8000 Bytes and everything seems to work properly even if I use a lot of pvPortmMalloc and vPortFree (which is value under the space is needed for Stacks, TCB, Queues etc.) I must point out that Tasks and queues are allocated statically with Heap_4. Thank you for advice.

Statically allocated memory, by definition, does not come out of the heap. The amount of memory available for use as the heap is the total memory available, minus statically allocated memory (minus the .data section, etc.). This is how compilers and linker behave, regardless if what your build includes FreeRTOS or not.

I am sorry but I still don’t understand. I set TOTALHEAPSIZE to 1000 Bytes, but why I can not set stack size for 3 statically allocated tasks for example to 256 words (every stack size 256 words)? At least CubeMX will not allow it. Because as you said, if it is allocated statically -the stacks for tasks will not come form the heap memory.

Why can’t you set the 3 statically allocated tasks stack sizes to 256 words? What is preventing you? Is it just CubeMX that won’t let you do it – and if so – how does it prevent you? (for example, will it just not let you enter the number or does it let you enter the number but then not let you link the application? What is configSUPPORTSTATICALLOCATION set to? What if you just edit the FreeRTOSConfig.h file without using CubeMX?

configSUPPORTSTATICALLOCATION = 1 (default from Cube) Screenshot is enclosed – this windows pops up when I try to change for example first stack size to 256 Cube allows me to set 3x 256 words but only when I increase the TOTALHEAPSIZE

The dialog box in the screenshot seems to indicate that the stack sizes were updated. What makes you think CubeMX is not allowing the stack sizes to be updated?

Please just look at my video: https://www.youtube.com/watch?v=ookcCYnF4k4&feature=youtu.be

Hi Richard, do you thing the behavior on the video is correct? (In case of static allocation of queues and tasks) Thank you very much. Best regards, Jan.

No idea – it is not a tool I use myself – suggest you ask ST.

This is a bug in CubeMX and nuthing to do with FreeRTOS… CubeMX stupidly checks total requested static stack space against TOTALHEAPSIZE…

Thanks Dave. I verified this using STM32Cube IDE and the same bug exists there. Jan, TOTALHEAPSIZE and the stack sizes for statically allocated tasks are not related. You should modify the generated code. TOTALHEAPSIZE is defined in FreeRTOSConfig.h: ~~~

define configTOTALHEAPSIZE ((size_t)2000)

~~~ Task sizes of the statically allocated tasks are defined at the time of task creation: ~~~ osThreadId myTask02Handle; uint32t myTask02Buffer[ 128 ]; /* Update the stack size here. */ osStaticThreadDeft myTask02ControlBlock; /* Pass the updated stack size to osThreadStaticDef instead of 128. */ osThreadStaticDef(myTask02, StartTask02, osPriorityIdle, 0, 128, myTask02Buffer, &myTask02ControlBlock); myTask02Handle = osThreadCreate(osThread(myTask02), NULL); ~~~ Just FYI, you can directly use xTaskCreateStatic instead of going via osThreadCreate wrapper. Thanks.

Thank you all. Now I’m clear about that! Jan.