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MSP430FR6972: using a TCXO to clock the MCU

Bart
Expert 6500 points

Part Number: MSP430FR6972

Team,

we would like to use a TCXO with MSP430 for measuring ACLK from another device (PPM of LFXT). Measurements with min. deviation of 2ppm or less are needed.

1. Which type of TCXO would be recommended?

  • Clipped Sinewave
  • HCMOS
  • LVCMOS
  • Sinewave
  • Square wave

   Would it be clipped sinewave or square wave the best choice?

2. Can you share some electric scheme how to connect TCXO to MSP430? (because it uses only one pin HFXIN, correct?)

3. Can you share some example of code?

Thank you
TI Customer

  • 0
    Guru 322000 points

    When in bypass mode, the XIN pin behaves like a digital input pin (see footnote 4 of table 5-5 in the datasheet), so anything except sine wave works fine.

    Section 3.2.3 of the User's Guide says:

    […] If HFXTBYPASS is also set, HFXT is configured for bypass mode of operation, and the oscillator associated with HFXT is powered down. In bypass mode of operation, HFXIN can accept an external square-wave clock input signal, and HFXOUT is configured as a general-purpose I/O. The PSEL bit that is associated with HFXOUT is a don't care.

    HFXOUT can be left open.

    To initialize the clock, use exactly the same code as for a 19.2 MHz crystal, but set HFXTBYPASS.

  • 0
    TI__Genius 14810 points

    Hello Bartosz,

    If Clemens's answer helped you find the answer to your issue please go ahead and select that your issue is resolved.

    Best regards,

    Matt

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