NxP MPC5744P – ucOS-III – IVOR6 Exception

NxP MPC5744P – ucOS-III – IVOR6 Exception

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This topic contains 1 reply, has 2 voices, and was last updated by  Sharbel Bousemaan 1 year, 3 months ago.

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  • #25173

    Nitin Nitin

    Hello Sir/Madam,

    I am using MPC57xx_VLE ucOS-III port on MPC5744P-DEVKIT. I referred to example project available for MPC5748G to create this MPC5744P based program.

    Functionality of this example program:
    1. On POR, the program jumps to bootloader at 0x00FB00000. This does nothing except jumping to application code residing at 0x01000000 by this code:
    // Disable all interrupts
    // Jump to application code _start residing at 0x01000000
    (((void) (*)(void))0x01000000)();

    2. In the application, I have created periodic tasks at rate 2ms, 10ms, 20ms, 100ms, 1s.

    In 2ms, 10ms, 20ms, tasks do nothing i.e., an empty infinite loop.
    In 100ms task, the LED is toggled.
    In 1s task, I am doing software reset by using the following code so that it enters to bootloader again.
    MC_ME->MCTL = 0x5AF0U;
    MC_ME->MCTL = 0xA50FU;

    => The program repeatedly jumps from bootloader to application and resets every second so that it starts with bootloader again and the cycle repeats.

    After a random no. of resets( it never triggered an exception in the beginning of execution), the program hangs with IVOR6 exception – Illegal instruction.

    Debug Trace:
    – IVOR6
    – 2msTask or 10msTask
    – 0x1B1B1B1Bu

    I note that this value 0x1B1B1B1Bu is assigned to R27 in OSTaskStkInit function and triggering Illegal instruction exception. But I do not understand why PC gets assigned to this invalid value after few resets.
    Could you please support and help in resolving the issue of reset triggering exception?


    Hello Nitin,

    Have you reviewed the impact of the MPU and Caches on your system?
    Perhaps your instruction/data caches need to be invalidated on reset.


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