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MSP430FR2433: Maximum SPI clock frequency

Robert Swan
Prodigy 70 points
Part Number: MSP430FR2433
Other Parts Discussed in Thread: MSP430G2553

I have recently ported an application from an MSP430G2553 to the MSP430FR2433.  That has gone well and everything is working nicely with the newer MCU.

However, reading the data sheet for the new chip I see that SPI is specified to have a maximum clock frequency of 8MHz.  I'm running MCLK and SMCLK at 12MHz and am running the eUSCI clock without a divider.  SPI output (which is used quite heavily) is working fine at 12MHz, and looks fine on the oscilloscope.  I'm reluctant to divide it down to 6MHz.

The old chip's data sheet said its SPI could handle anything up to MCLK.  It is unusual for a newer chip to claim poorer performance.  Was it just TI being conservative or will I face real reliability problems running at 12MHz?

Thanks.

  • 0
    TI__Guru 63891 points

    Hello Robert,

    The design of SPI peripheral in the MSP430FR2433 may have some limitation that cannot guarantee its operation at 16MHz across the entire operating voltage and temperature ranges.  Therefore it is spec'd at only 8MHz.  I'm assuming you are operating at room temperature so running at 12Mhz is most likely not a problem.  However, running it at 2.0v and at -40C or +85, you may find that it may not work properly at 12MHz.

    Also, please refer to this helpful application note regarding how to calculate the maximum "useable" SPI clock speeds.  See section 4.2.

  • 0
    Prodigy 70 points
    Thanks for that Dennis. Yes, room temperature and 3.0v. I think it'll be fine. If not, the application already has an option for clock divider. I'll keep the default at 1. The application note was a good read too.

    Thanks again,

    Robert.

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