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EVM430-FR6047: Newly added parameter in GUI

Andre Conjusteau
Prodigy 80 points
Part Number: EVM430-FR6047

Hello,

In the Advanced Parameters tab there are now two new values: Envelope Crossing Threshold and Search Range. These variables are not described in my version of the Ultrasonic Design Center user's guide (SLAU720B). Is there a new version of the guide, or are these parameters explained online somewhere?

Thanks,

Andre'

  • 0
    TI__Mastermind 38620 points

    Hello Andre,

     

    The latest design Center users guide is included with each release of the software. It can be found at the link below.

    http://software-dl.ti.com/msp430/msp430_public_sw/mcu/msp430/USSSWLib/USSSWLibWater/latest/

    These two new parameters are included in this document, but only the min/max values are described. You can find some more information in the document below which discusses our correlation based technique (2.2.1.1, #3), but I will also provide some detail on selecting the correct value.

    http://www.ti.com/lit/an/slaa889/slaa889.pdf

    Envelope Crossing Threshold – As discussed in SLAA889, this threshold is set to select the wave lobe that we would like the AbsToF algorithm to lock on to. When you look at your ADC capture, the threshold should be set where there is a maximum rate of change between lobes. The idea is that you want a clear threshold so that the same lobe is always selected during the acquisition procedure and not some borderline value. This is typically the 2nd or 3rd lobe. The first lobe could have some noise before it which may in some cases get selected instead of the real lobe. You can think of the envelope crossing threshold value as a ratio of the maximum ADC signal. If your signal has a maximum value of 900 codes and your setting is 0.11(default), the lobe closest to 99 will be locked(900*0.11).

    Search Range – This is not used in latest release and will be removed. Whatever value is put in this parameter will have no effect.

    If you would like to ensure that you are locking on to a good lobe, please provide a screenshot of your ADC capture and I can provide my suggestion.

  • 0 in reply to Eddie LaCost
    Prodigy 80 points

    Hi Eddie,

    Thank you for the prompt answer and referring to the document slaa889, which I had missed (the TI library is exhaustive, but hard to navigate). If I need further assistance with the algorithm, I will start a new thread for the sake of clarity.

    Regards,

    Andre'

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