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MSP430FR6047: EVM430FR6047

ido amgar
Intellectual 440 points

Part Number: MSP430FR6047

Tool/software:

Hi I'm trying to measure TI's LFXTIN clock in EV.
I saw that it is in component Y2 and I touch it with a scope and I get a sine wave with a low amplitude at a frequency of 32 kHz.
Does it have to be like this?
Why don't I see a square wave?

  • 0
    TI__Genius 16050 points

    Hi Ido,

    It is not uncommon for a crystal oscillator to produce a sinusoidal waveform rather than a square wave. The XTAL pin inputs are intended to utilize this waveform, as opposed to a CLK_IN signal, which expects a square wave. The XTAL inputs have drive circuitry to create a square waveform from the sinusoidal waveform from the crystal.

    With that being said, some crystals will produce a square wave. Looking at the Y2 crystal's datasheet, I do not see an expected output waveform. For a higher frequency crystal, I would recommend that you ensure you have a high bandwidth probe to make sure you aren't just attenuating the high frequency components of the waveform, making it look more sinusoidal. But on a 32kHz crystal this is likely not an issue.

    Are you actually seeing a problem related to the crystal behavior? Or are you just curious why the oscilloscope doesn't show a typical clock signal?

  • 0 in reply to Dylan OBrien
    Intellectual 440 points

    I'm just looking for a place where I can sample the 32KHz clock as a square wave.
    I want to see him on the scope.
    Can you direct me where I can find it for sure?

  • 0 in reply to ido amgar
    TI__Genius 16050 points

    The square wave would be generated inside of the device. You could activate the clock output function of one of the pins and output it that way. To do this you'll need to find which clock the crystal is being used for, then activate that pin function as shown in the pin attributes section of the datasheet.

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