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Original question:

MSP430FR6047: Parameter problem in MSP430FR6047< ussswlib. h>

MSP430FR6047: Calculate the relevant parameters required by TOF

user4326664
Prodigy 50 points
Part Number: MSP430FR6047
Other Parts Discussed in Thread: TDC1000

Q1:Calculate the time between the sensor sending pulse from CH0 and the signal received by CH1，Is it the same as in the picture only these two parameters？（startADCsamplingCount  and capture duration）

Q2:Is there a timing chart updated now？like TDC - 1000 's datasheet?

  • 0
    TI__Genius 12615 points

    Hi Yuxing,

    You're timing diagram is correct. These are the two parameters that affect the window. We don't currently have a timing diagram that looks like the TDC1000 in our documentation.

    BR,
    Leo

  • 0 in reply to Leonardo Estevez
    Prodigy 50 points

    Thank you Leonardo Estevez ,

    I have another question.

    The distance between the two sensors is 1cm,The simulation results and calculation formula are shown in the figure below.

    HSPLL_CLOCK_FREQ=80MHZ, SO ASQ clock=5MHZ. We can calculate the time 530us by (1/ASQ_clock_freq)*(1)*(startADCsamplingCount),The velocity in the air is 340m/s, the result is 0.1808m, which is different from the reality.And I left out the time in pcapturebuffers in my calculations. Did I make a mistake? Or is there something missing?

  • 0 in reply to user4326664
    TI__Genius 12615 points
    Hi Yuxing,
    I recommend using the GUI in your experiments to begin with. The relevant parameter is called "Gap between pulse start and ADC capture". You also have your transducers very close to each other, so it's possible that you may be seeing a secondary(or later) reflection instead of the initial ultrasonic signal in the ADC capture window. You might try spacing your transducers further apart in your initial experiments (ie. 10 cm).
    BR,
    Leo
  • 0 in reply to Leonardo Estevez
    TI__Genius 12615 points

    Hi Yuxing,

    Were you able to identify the issue when using the GUI?

    BR,
    Leo

  • 0 in reply to Leonardo Estevez
    Prodigy 50 points

    Hi Leo,

    I just started testing again in the last few days.

    The sensor frequency on the GUI didn't work for me, so I tested it with the program.

    I change the value of startADCsamplingCount, close to the signal to the left of the ADC Capture Tab as below, so I can ignore this part of the time in the calculation.

    startADCsamplingCount=2660,the distance between the two sensors is 1cm.

    startADCsamplingCount=3192,the distance between the two sensors is 5cm.

    startADCsamplingCount=3458,the distance between the two sensors is 7cm.

    Calculate the time by (1/ASQ_clock_freq)*(1)*(startADCsamplingCount) and the results are as follows:530us,638.4us,691.6us.The velocity in the air is 340m/s, the distance between the two sensors is calculated as: 0.1808m,0.2171m,0.2351m.The difference between them is roughly true.

    It's possible that there's something really wrong with my test conditions.

    Does anyone else have this problem?

    BR,

    yuxing

  • 0 in reply to user4326664
    TI__Mastermind 27505 points

    Hi Yuxing,

    Are you sure that you are capturing the initial signal instead of the reflecting one?

    Best Regards,

    Cash Hao

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