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MSP430FR6043: About measuring high-speed flow rate

U-SK
Genius 5840 points
Part Number: MSP430FR6043


Hello,

Are there any limitation about the maximum value of dToF?

If so, what is the measurable range of dtof?

Regards,

U-SK

  • 0
    TI__Mastermind 46765 points

    Hi,

    The dTOF is saved as iq44 format in the example code. The measurable range for an iq44 format is from -(2^32)/2^44 to (2^32-1)/2^44.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Genius 5840 points

    Hi Cash,

    Thank you for your reply.

    Is my understanding correct that the maximum dTOF time that can be measured is (2^32-1)/2^44 sec(244.141us)?

    Is it possible to measure dToF longer than the above by modifying the software?

    Could you tell me the maximum dToF time that can be measured as hardware?

    Regards,

    U-SK

  • 0 in reply to U-SK
    TI__Mastermind 46765 points

    Hi,

    You can not get a longer range of dTOF easily by changing software. In the meter application, we want the dTOF to be extremely accurate. So we choose to use iq44 format to store it. If you want to get longer range of dTOF, I suppose you would not need a high accuracy for the bigger range, so you can use dTOF = (absTOF1 - absTOF2) to get the dTOF value. The absTOF is store as iq40 format. You should get a longer range of dTOF by this way.

    By the way, the range for an iq44 format should be -(2^31)/2^44 to (2^31-1)/2^44.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Genius 5840 points

    Hi Cash Hao,

    Thank you for your reply.

    Could you please also confirm about following question?

    Is my understanding correct that the maximum dTOF time that can be measured is (2^32-1)/2^44 sec(244.141us)?

    I'm happy if you could tell us the units of the dTOF range you told.

     

    Regards,

    U-SK

  • 0 in reply to U-SK
    TI__Mastermind 46765 points

    Hi,

    No, I am telling you that the data format we used to store the dTOF data is iq44. And the range for an iq44 format -(2^31)/2^44 which is around -122us to (2^31-1)/2^44 which is around 122us.

    In our USS library, we have other limitations on calculating the dTOF result. So, the maximum dTOF value usually smaller than 122us. I can not give out the exact max dTOF value because it is related to other parameters.

    Since you are looking for a large range of dTOF value, I am guessing you are not using it in water/gas meter application. The dTOF calculation approach in the USS library might not fit in your application. That is why I am offering you a different dTOF approach to get a large range in the former reply.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Genius 5840 points

    Hi Cash Hao,

    Thank you for your reply.

    I understand.

    Regards,

    U-SK

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