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TDC1000-TDC7200 USB Disconnection Issues

Norman Curato
Prodigy 110 points
Other Parts Discussed in Thread: TDC7200, TDC1000

Hi,

I've setup the TDC1000-TDC7200 EVM so that it can actually measure fluid level by rigging a submersible pump inside a container to have the water level rise and fall. I was expecting the TDC7200 to calculate and provide results for each variation. Except I found out that I have to mechanically bond the sensor to the container and not just stick it on like many people did. 

Now my other problem is when I turn off the pump so that water level can fall, the USB connection from the TDC1000 EVM is cut. I tried using a totally separate source but the same thing happens. Why do you think this happens?  

Best regards,

Norman

  • 0
    TI__Expert 4725 points

    A few quick questions:
    1. What do you mean by "USB connection from the EVM is cut"?
    2. Are you assuming its "cut" beause the TOF graph stops advancing? Check your board LEDs (D2 - Link: shuold be soild, D3 -Measurement: should be flashing)
    2. Are you monitoring the START (TP7) and the analog echo, COMPIN(TP15) with an oscilloscope? I highly recommend this as it will give you a better understanding of your ultrasound system.
    About transducer mounting see the following. In a nutshell mounting techniques are everything.


    e2e.ti.com/.../403742

  • 0 in reply to Matthew Minasi
    Prodigy 110 points

    Hi Matthew,

    1. To power the EVM I need to insert it to my PCs USB port , right? 

    2. Everything is working after power up. LEDs blinking OK. We used a submersible pump to make the water level rise and fall to test the level-sensing features of the EVM. The pump is 220VAC and is not connected whatsoever with the EVK. When I turn off and on the pump, the connection to the EVM via USB is disconnected. I have to unplug the USB and plug it again for me to observe the T.O.F. changing.

    3. Yes we used a scope already and we can see all the start and stop pulses.

    I think its a grounding issue. So I will try to resolve it by properly grounding the system. 

    Best regards,

    Norman

  • 0 in reply to Norman Curato
    TI__Expert 4725 points
    Norman,
    You are right it sounds like your pump switching is affecting the USB/EVM connection.
    Did you remember the reverse biased diode across your relay coil? Good luck!
  • 0 in reply to Matthew Minasi
    Prodigy 110 points

    Hi Matthew,

    Placing a ferrite bead around the pump's AC line and the USB cord seemed to work. I'm going to test it out further today and post my results later. 

  • 0 in reply to Matthew Minasi
    Prodigy 110 points
    Hi Matthew,

    I did place a reverse biased diode on the relay coil and also placed ferrite beads around the USB cord and the pump's AC line. I observed that the problem exists depending on the AC line itself. If the AC outlet includes a ground, generally the problem does not occur.