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Manoj Chandran
Manoj Chandran
Associate
October 11, 2017
Question

CPU Load using Ulink Pro

  • October 11, 2017
  • 1 reply
  • 1527 views
Posted on October 11, 2017 at 16:13

Hi,

We are using STM32F479 processor in our design. We want to calculate the CPU load using Ulink Pro. We are unable to get the performance analysis using ulink pro when the system clock is 168MHz (system_stm32f4xx.c - (DFP 1.0.7)). If the system clock is configured to  140 MHz or lesser, it is working. Could any one please help to sort out the issue. One point is, we have select device as STM32F439 in keil since we are using older version of keil and it supports processor only upto STM32F439.

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    1 reply

    Tesla DeLorean
    Tesla DeLorean
    Guru
    October 11, 2017
    Posted on October 11, 2017 at 16:58

    One would bench performance internally using DWT_CYCCNT, which will be fine >200 MHz

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    Manoj Chandran
    Manoj ChandranAuthor
    Associate
    October 12, 2017
    Posted on October 12, 2017 at 07:14

    Hi Clive,

    Thank you for the response.  We want to calculate is total CPU load of the actual application and also the code coverage of the program. Using ulink pro, when the SystemClockfrequency is set to less than 120MHz (PLL_N 240 and PLL_P 2) we are able to get the details but when set to 168MHz (frequency above 120MHz) we are unable to get the code coverage and Performance analysis. 

    Regards,

    Manoj

    Tesla DeLorean
    Tesla DeLorean
    Guru
    October 12, 2017
    Posted on October 12, 2017 at 14:21

    Yes, no doubt because you've hit the bandwidth limit of the probe. You're going to have to either scale the numbers, or change your approach.

    I'd suggest you instrument the code so you can count cycles across routine enter/exit points. You could also use GPIO pins and a scope to monitor loading, for example around a WFI loop in your idle routine.

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