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PGA460-Q1: GUI vs Energia code - Dump profile byte parameter shifting

Kwok Leo
Prodigy 180 points
Part Number: PGA460-Q1
Other Parts Discussed in Thread: ENERGIA

Hello Team,

I've a problem to compare the parameter byte shifting issue to compare between GUI and my Energia program code.

Here is find the dump profile data and chart which measured in one samples and difference configuration setting. It could see the GUI's dumping data show the first 4 byte parameter are [7, 81, 154, 244]. However, while used the Energia with difference baud rate and the owuShift in .cpp file that all of the first 4 byte parameter are difference and seem the parameter shifted.
It is cause to affect the decay period time after burst stage and it is serious problem in our application because we measure in short distance.

Here i list out the first 4 byte as below:

GUI [7, 81, 154, 244]

Energia : 115.2k, owuShift =2 [6, 205, 255, 255]

Energia : baudrate=9.6k, owuShift = 2 [81, 159, 244, 255]

Energia : 115.2k, owuShift = 0 [7, 107, 22, 205]

Energia : 9.6k, owuShift = 0 [7, 45, 81, 159]

Here is my question : 

1. Why and how the difference buadrate and owuShift affecting the fist byte paratmer?

2. How we figure out the the parameter byte shifting to align with GUI parameter?

3. Any Energia reference code can show and detect this parameter shifting issue?

Thanks,

Leo

  • 0
    TI__Mastermind 21940 points

    Leo,

    We have some reference code material published here:

    https://www.ti.com/lit/an/slaa730a/slaa730a.pdf

    https://www.ti.com/lit/zip/slac741

    It appears from your measurement results that the Baud Rate = 115.2k with an owuShift = 0 is closest to the GUI result you have captured. Your owu_shift variable appears to be forcing a direct time delay shift of 2 time slots.  It is not clear to me why your baud rate variable is resulting in a time shift in your recording.  I would start by examining the code related to the setup of the One Wire interface to see if there is any variation between how the two baud rates are being configured.

    Thanks,

    Scott

  • 0 in reply to Scott Bryson
    Prodigy 180 points

    Hello Scott,

    Thanks your response.

    Baud Rate=115.2k with owuShift=0 which seem is closest to the GUI result, but it also see that there has a deep amplitude in the third byte.: [7, 107, 22, 205]. Would you also do some examining to review this issue?

    Thanks,

    Leo

  • 0 in reply to Kwok Leo
    TI__Mastermind 21940 points

    Leo,

    It appears you are referring to the dip that occurs during the rise of the first pulse during the initial excitation of the transducer.  It is not entirely uncommon to observe dips like this that occur as the transducer is beginning to be excited.  The echo results during this time are not useful until the ringdown delay of the transducer is completed.  I would recommend repeating the test multiple times to observe the repeatability of the dip, and expect that you may see it will vary somewhat.

    Thanks,

    Scott