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MSP430F5333 Oscillator Question

Nicholas Ipri
Expert 1010 points
Other Parts Discussed in Thread: MSP430F5338, MSP430WARE, AM3354

Hi!

I am using the above mentioned component with an 8 MHz 3.3v LVCMOS external clock oscillator on XT2IN (and leaving XT2OUT unconnected) For your reference, the oscillator a CTS CB3LV family product

I want to verify that the 3.3v level is OK for the processor (as opposed to a 1.8v level). The oscillator is powered from the same 3.3v rail that powers DVCC. I also need to verify how to set XT2BYPASS and XT2BYPASSLV for this mode of operation.

Thanks!

  • 0
    Expert 1010 points

    Correction: The correct P/N is MSP430F5338...

  • 0 in reply to Nicholas Ipri
    TI__Expert 6760 points

    Hi,

    There are API's in the driverlib folder in the ucs.c file that can configure the XT2 crystal either in bypass mode or not in by-pass mode.  You can call these API from your application.

    The driverlib folder can be downloaded, by downloading MSP430Ware.

    Regards,

    Arthi Bhat

     

  • 0
    Guru 25210 points

    Nicholas Ipri said:
    I want to verify that the 3.3v level is OK for the processor (as opposed to a 1.8v level). The oscillator is powered from the same 3.3v rail that powers DVCC.

    The voltage for I/O pins (XT2xx included) is the same as what is supplied on DVCC. The 1.8V you mention is what powers the internal core.

    Nicholas Ipri said:
    I also need to verify how to set XT2BYPASS and XT2BYPASSLV for this mode of operation.

    Refer to Figure 5-1 in the User's Guide. Chapter 5.2.5 explains how to set XT2BYPASSLV.

  • 0 in reply to Brian Boorman
    Expert 1010 points

    >>The voltage for I/O pins (XT2xx included) is the same as what is supplied on DVCC. The 1.8V you mention is what powers the internal core.<<

    Thanks. I understand that 1.8v is the core voltage. I am just trying to verify that I can actually drive XT2IN to 3.3v with the clock osc. I am asking because I just completed another design using a Sitara AM3354 processor on which the VIO rails are at 3.3v but the XTAL input pin cannot be driven above 2.0 Vmax. I am simply trying to avoid overdriving the pin.

    If I understand correctly, I can use a 3.3v oscillator on XT2IN if I set XT2BYPASS to 1 and XT2BYPASSLV to 0.

  • 0 in reply to Nicholas Ipri
    Guru 25210 points

    Nicholas Ipri said:
    I am just trying to verify that I can actually drive XT2IN to 3.3v with the clock osc.

    There is nothing in the MSP430F5338 datasheet to indicate that it supports the 1.8V XT2BYPASSLV mode of operation. Lacking that, the standard case applies - voltage range is 0 to DVCC. Re-read 5.2.5 in User's Guide.

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