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Do SPI can be used immediately?

da
Expert 2780 points
Other Parts Discussed in Thread: MSP430F6746

Hi! 

My customer is using the MSP430F6746.
They have a Question.

They use the SPI, but when they do not use the SPI believes that attempt to reduce the power consumption by switching to GPIO.

Q1
Is this idea is correct?

Q2
After switching to the GPIO, when they were switched again to SPI, the waiting time is necessary?


Regards,
Da

  • 0
    Guru 25210 points

    da said:
    Q1
    Is this idea is correct?

    It doesn't hurt, but I don't believe it buys them anything either. The lowest power state of an I/O pin is when it is an output and is in the logic '0' state. If the SPI peripheral is configured that the idle state of the clock and data lines is low, then there is no benefit to switching to GPIO. The one thing to check is the state of the SIMO line after SPI use (I'm not sure if the static state matches the last bit set).

    da said:
    Q2
    After switching to the GPIO, when they were switched again to SPI, the waiting time is necessary?

    No waiting time. If you look at the I/O schematics, you will see that this is a mux on the I/O cell. By the time the CPU instructions to change the mode have executed, the I/O cell will be switched before the next instructions could even access the USCI module.

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