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Date of registration: May 11th 2018

Posts: 2


Friday, May 11th 2018, 12:28pm

OZONE FreeRTOS HALT EmptyCallStack when using Float

I am using OZONE(V2.56i) to debug FreeRTOS on a STM32F437, Compiler GCC (Atollic TrueStudio for STM32 Version: 9.0.0 )

Starting the Programm In the Ozone-Debugger and Pause it(== crtl+F5), i can see the complete List of all FreeRTOS Tasks
and by clicking the Task, i see the assoceated CallStack of the Task.
- OK

The CallStack of one Task disappeares compleatly after some time (Only a Null- Pointer is shown)

This happens exactly after the first use of any FLOAT in this Threat - and stays until the next restart of the System.

Changeing the Code to Integer-Aritmetic (Fixpoint-Integer/ Q31) helps to overcome the Problem - for some time.

The critical Threat is my GUI-Thread.

I am using emWin. (ST-library version)

when opening a Window, that uses a Circle or ARC (In AA-Mode) the problem is back (- no CallStack shown in OZON ) for this thread (after pausing the thread).
- I suppose there are some trigonometric functions like SIN inside the Draw-Circle(==using floats)

By elininating the Circles, the OZONE works fine, and i have the CallStack.

==> I tried to switch emWin to Software-Floats, but i could not manage.

When using a Breakpoint in the Thread, the Call-Stack is correct shown - the effect only occurs, when pausing the System in the Ozone-Debugger.

I need the pause-functionality in Ozone with the Call-Stack, because the Thread hangs some times (Closed-Loop), and i do not know where --> (No Place to set the Breakpoint)

I would be nice, if i can debug the Threads in Ozone, when Hardware-Supportet Float aritmetic is enabled


Super Moderator

Date of registration: Jan 2nd 2017

Posts: 1,048


Wednesday, May 16th 2018, 12:00pm


Thank you for your inquiry.
Such an issue is now known to us.
Could your provide us with a reproduction example project?
Any STM32F4 eval board as baseboard would suffice.

Best regards,
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Date of registration: May 11th 2018

Posts: 2


Wednesday, May 16th 2018, 4:47pm

Also reproduceable in Atollic with FreeRTOS --> Seams a Problem of the J-Link FreeRTOS Awarenes

During preparing an Example for You, i discovered, that it is the same in Atollic-Debugger.

--> seems to be a Problem with the FreeRTOS awareness of the J-Link, not a Problem of Ozone

1) STM32F429I-DISCO, ST-Link changed to "J-Link On Board" with J-Link Reflash utility to enable FreeRTOS-Awareness
2) CubeMX Project generated Project with 2 aditional Tasks, one calling a Subroutine with a Float
3) Pressing Pause --> You will get the Pictures in the attachement: The CallStack of myTask02/StartTask02 is empty
ItsMe has attached the following images:
  • EmptyFreeRtosCallStack_InAtollic.png
  • MainWithFloat_InAtollic.png
ItsMe has attached the following file:
  • CubeMX_Main.zip (10.45 kB - 6 times downloaded - Last download: Yesterday, 5:24am)