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TIDM-1019: TIDM-1019 ADC Capturing

Jejomar Ildefonso
Expert 8590 points
Part Number: TIDM-1019

Hi Team,

Good day! Need your expertise on our customer's inquiry below:

"I have a question about ADC capturing of TIDM-1019. My system's TOF is about 7us and I wanna capture echoes using internal ADC but there is a parameter in GUI called "Gap between pulse start and ADC capture(us)" with minimum value of 20 (in Water Mode), so I think ,I will loss the first reflected wave!
Now the first question is this, What's the minimum TOF that MCU can calculate and also how can I capture input waveform using internal ADC when the TOF is 7us?

Could I capture 14'th echo (reflected wave) ,If I set the parameters like this:
Transmit frequency = 1MHz (T = 1us and TOF = 7us, so the first reflected wave will received at 7us and 14'th reflect at 20us)
Gap between pulse start and ADC capture(us) = 20
Number of Pulses = 30 and more ?
Is there any better solution?"


Kind Regards,

Jejomar


  • 0
    TI__Expert 7365 points

    Hi Jejomar,

    Jejomar Ildefonso said:
    What's the minimum TOF that MCU can calculate and also how can I capture input waveform using internal ADC when the TOF is 7us?

    The library should be able to calculate a TOF of 7us. To support a "Gap between pulse start and ADC capture(us)" of just 7 us, you will need to increase the "Start PPG COunt(ns)" in the Advanced parameters tab to 40,000 ns. The default setting is 10,000 ns.

    Jejomar Ildefonso said:
    Could I capture 14'th echo (reflected wave) ,If I set the parameters like this:

    If the actual transducer spacing is 7 us and you set the "Gap between pulse start and ADC capture(us) = 20", the received signal will look something like in Figure 4-7. "Gap Between Pulse Start and ADC Capture Set Too Long" of the app note Water Flow Meter Quick Start Guide (Rev. B) (https://www.ti.com/lit/pdf/slau810). We have always tested the library when the received signal is in the form of Figure 4-6. "Captured ADC Signal" of the above app note.

    If you anyway know that you want the ToF of the 14 th tone and using 1 MHz tranducers, you can just add 14 us to the computed TOF after setting "Gap between pulse start and ADC capture(us) = 7".

    Srinivas

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