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Original question:

MSP430FR6047: he difference between MSP430FR6047IPZ and MSP430FR6047IPZR

MSP430FR6047: Unstable ToF and flow rate measurement and converting flow rate to volume

Behnam Madadnia
Intellectual 500 points

Part Number: MSP430FR6047

Dear Engineers,

We are working with the TI MSP430FR6047 evaluation board to measure flow rate and volume. In our measurements, everything seems to work correctly, and the ToF is well correlated with the changing flow rate. However, we observe occasional jumps in the flow rate. As shown in the attached picture, there is approximately a 1.5% fluctuation under a constant flow rate.

 

Value Difference vs. Reference Percentage Difference
4.030336 (Reference) 0.000000 0.00%
4.087739 +0.057403 +1.42%
4.025302 −0.005034 −0.125%

First question: Would you please let me know how I can obtain a much more stable value? What should be changed or improved in my code?

Second question: How can I read out the accumulated volume value? Is the accumulated volume already calculated in the USS library, or do I need to calculate it myself? If I need to implement it myself, how should I do that?Flowrate.JPG

 

Regards,

 

  • 0
    TI__Expert 7285 points

    Hi Behnam,

    Behnam Madadnia said:
    Would you please let me know how I can obtain a much more stable value? What should be changed or improved in my code?

    Besides considering some measurement error, please also note that occasional fluctuations in flow rate could also be caused by a tiny change in the water flow during testing. As it can be seen from your figure, the jump is mainly caused by the delta TOF measurement. If possible, you can refer to the Ultrasonic Water Flow Meter Design and Testing Academy to use GUI to capture dTOF curve to see the standard deviation and mean value.

    Behnam Madadnia said:
    How can I read out the accumulated volume value? Is the accumulated volume already calculated in the USS library, or do I need to calculate it myself? If I need to implement it myself, how should I do that?

    USS Library doesn't support automatically accumulate the volume, need users to calculate by themselves, you can refer to the following thread for more details.

    water flow detection for MSP430FR6043

    Best Regards,
    Peter

  • 0 in reply to Peter Jiang
    Intellectual 500 points

    Dear Peter,

    Thank you very much.

    Could you please let me know if there is any averaging filter inside the USS that can be enabled to smooth the ToF measurements? I can implement an FIR filter myself to address the issue, but it introduces some delay. I would prefer to use an internal feature of the USS library if such a filter exists.

    If there is an internal averaging or smoothing option, could you please explain how to configure it and which parameters in the USS library settings need to be adjusted?

    Regards, Behnam

  • 0 in reply to Behnam Madadnia
    TI__Expert 7285 points

    Hi Behnam,

    Sorry to tell that as far as I know we do not provide any internal filter options in the library, it needs users to achieve it by themselves.

    Since you mentioned that when you perform the FIR filter which will cause some delay, maybe LEA module would be helpful, you can refer to the following documents and related resources for the implementation details Ultrasonic Sensing Subsystem Reference Design for Water Flow Measurement

    Best Regards,
    Peter

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