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MSP430FR60431: MSP430FR60431 – Flow Rate Accuracy Issue on Custom Board Using USS Library

Dinesh Kannan
Prodigy 50 points

Part Number: MSP430FR60431
Other Parts Discussed in Thread: MSP430FR6047, MSP430FR6043

Tool/software:

Hello TI Experts,

We are currently using your MSP430FR60431 microcontroller on our custom-designed flow meter board. With the help of the USS_02_40_00_00 software package and the MSP430FR6047 EVM, we made adjustments tailored to our flow tube characteristics and successfully generated the required USS_CONFIG folder files using the USS Design Center.

We then ported the FR6043_USSSWLib_template_example project (originally for MSP430FR6043) to our custom board with MSP430FR60431, using Code Composer Studio. Initially, we faced several integration issues during bring-up, but with guidance from this forum, we were able to overcome them—thank you!

At present:

  • Ultrasonic signal capture and processing work correctly.

  • We've customized the USS_TEMPERATURE_LUT_TRANSDUCER_CONST for our transducers and are getting accurate temperature readings.

  • We are using USS_Algorithms_Results.volumeFlowRateNoCalib to compute real-time flow (in mL/sec), and accumulate it over time to generate total flow.

Problem:

  • At low flow rates, the total flow error shows non-linear (arc-like) behavior.

  • At high flow rates, readings become inaccurate or fail completely.

We’ve attached our flow repeatability test results for your review.

Could you please help us identify the root cause and recommend any changes—either in USS configuration, gain settings, thresholds, or anything else—that might resolve this?

Thanks in advance for your valuable support.DN25Results.xlsx

  • 0
    TI__Mastermind 46765 points

    Hi,

    I believe that the Real puls. K is volumeFlowRateNoCalib from MCU. So, at flow rate 401 LPH to 451 LPH, there is the first drop on the volumeFlowRateNoCalib. At flow rate 2005 LPH to 2481 LPH, there is a second drop on the volumeFlowRateNoCalib. 

    It could cause by the cycle slip issue on the absTOF/dTOF result. Please record these TOF values and check if there is a significant change around those two flow rate range. If you confirmed there is a cycle slip issue on the absTOF/dTOF result. You can try with different envelop crossing threshold to solve the cycle slip issue first. 

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 50 points

    Hi,

    Thanks for your detailed reply and for highlighting the potential cycle slip issue.

    In my previous post, the TI team mentioned that there was no need to change the envelope crossing threshold. (Reference: TI E2E Forum Post)

    However, based on your suggestion, I would like to clarify a few points:

    • Is it actually necessary to change the envelope crossing threshold to address the observed drop in volumeFlowRateNoCalib at the 401–451 LPH and 2005–2481 LPH flow ranges?

    • How can I confirm that absTOF/dTOF results are affected by cycle slips in these regions?

    • If a change is needed, how should I correctly determine and set the new envelope crossing threshold so it remains stable and does not require future adjustments?

    • Lastly, is any calibration required when adjusting this threshold?

    Appreciate your insights on this.

  • 0 in reply to Dinesh Kannan
    TI__Mastermind 46765 points

    Hi,

    In that post, it was talking about if it is necessary to use a dynamic threshold. But in your case, the original seems not suitable to cover the whole flow ranges. Usually you can find a constant threshold setting to cover the whole flow rates and no need to adjust it. 

    You can directly records the absTOF and dTOF result during your flow test. And check if there are any drops on those data. 

    Please refer to this guide for how to set a proper parameters. https://dev.ti.com/tirex/explore/node?node=A__AUxLkAvzLrljvLBB0bSqSw__MSP430-ACADEMY__8HaEUeq__LATEST

    It does not require calibration when you adjusting threshold. The flow rate calibration only happens after you have settled all the parameters. 

    Best regards,

    Cash Hao

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