How to use a external crystal on the F28069

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Submitted by j_caracas on Sat, 11/17/2012 - 19:22 

Hi,

I need to use an external crystal on the F28069, but i can't configure this kind of oscillator. What should i do?

Tks

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    Submitted by j_caracas on Sat, 11/17/2012 - 19:36.

    I'm having a frequency jitter probably caused by the internal oscillator errors. I'm trying to generate a 60Hz fundamental frequency using a filtered PWM, what the oscilloscope shows is a frequency varying between 60.4 and 60.7 Hz.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    Submitted by Anders89 on Sat, 11/17/2012 - 22:23.

    Select Embedded > Piccolo > F28x Config...
    In the Clock Source drop down, choose External Oscillator

    But since you haven't attached your debug diagram that runs the generated code on the target, and because you checked Enable Interactive Peripheral Mode in the diagram you supplied, we think you might be running your control on the PC and only using the JTAG (100Hz bandwith) to communicate with on-target peripherals. This would explain your jitter. If this is the case, I suggest you view the movies here to see how to compile and debug a VisSim diagram.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited November 2020

    Submitted by j_caracas on Sat, 11/17/2012 - 22:58.

    I'm compiling and and using debug code. I have alredy tried to check the clock source to use the external oscillator, however the vissim automatically changes it for internal oscilator 1.

    Please see the attached diagram. I'm downloading it to the DSP and it generates a 12500 Hz pwm, that after filtered gives me a 60.57Hz (varying 0.5%) sinusoidal wave. How can a i make it stop varying?

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    Submitted by j_caracas on Sat, 11/17/2012 - 23:01.

    Anders89 is there anyway to have real time conversation with you? messenger, skype, FB, Gmail, Whatsup?

    I have tested the same code into a F2808 and a F28335 (both using external crystal oscillators) and it works perfectly. with no jitter and with exactly 60Hz.

    And also i tried downloading the code into 3 different F28069 control sticks, thus ensuring that isn't a hardware problem.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    Submitted by j_caracas on Sat, 11/17/2012 - 23:10.

    Just as a comment: I know that the F28069 control stick doesn't have a crystal on board. I intend to add one soldering it directly to the DSP pins.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited June 2016

    Submitted by j_caracas on Fri, 11/23/2012 - 02:50.

    Although I'm selecting the clock source as external oscillator, the code isn't being executed. Probably there's no clock. What can i do to solve this?

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