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MSP430FR6047: Execution time estimation

Mihir Gupta65
Intellectual 2155 points

Part Number: MSP430FR6047

Hi Team,

A customer is asking the following question about the MSP430FR6047>

How long will it take to execute  square root of a 32 bit number and a multiplication of a 16 bit numbers on MSP430FR6047 microcontroller? Is this MCU fast enough to do 24 multiplications of 16 bit numbers, then 32 bit addition of 24 numbers and one square root of a 32 bit number in 3 us time while doing DMA transfers at the same time?

Is there any way to be able to estimate the execution time or the number of cycles it would take to do this?

Thanks and Regards

Mihir

  • 0
    TI__Expert 6635 points
    Hey Mihir,

    I don't think this device can meet those timing requirements.

    The user's guide for the hardware multiplier (MPY32) states that "the result of a 8-bit or 16-bit operation is ready in three MCLK cycles" (this is in section 5.2 of the user's guide - linked below).

    www.ti.com/.../slau367o.pdf

    The max frequency we can run MCLK on this device is 16MHz. One clock cycle at this frequency is 0.0625us. This means it will take 0.1875us for one 16 bit operation (3 clock cycles). 24 multiplications of 16 bit numbers will take 0.1875us * 24 = 5us, which already puts us over the 3us time limit. This also has not taken into account the 32 bit addition of 24 numbers, calculating the square root, and DMA transfers.

    Thanks,

    Mitch
  • 0 in reply to Mitch Ridgeway
    Genius 3850 points

    Compile it on your chip, flip a pin and you know precisely how many cycles it takes. No point in guessing.

  • 0
    Guru 34803 points

    Mihir Gupta65 said:

    Is this MCU fast enough to do 24 multiplications of 16 bit numbers, then 32 bit addition of 24 numbers and one square root of a 32 bit number in 3 us time while doing DMA transfers at the same time?

    In MSP430 family, CPU and DMA can not work together in parallel. When DMA is working, CPU is stopped.

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