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A problem receiving signal on TDC1000

Evgeny Erenburg
Intellectual 430 points
Other Parts Discussed in Thread: TDC1000

I am working with TDC1000. Transducers a connected to  TX1/RX1 and TX2/RX2 pins.

The settings are following:

  1. Mode 0 : CH_SEL = 0 => TX1/RX2, CH_SEL = 1 => TX2/RX1 (can not be changed – TX1-RX1 connected together and TX2-RX2 connected together)

  2. Standard TOF Measurement. ( I also tried different modes).

  3. Current channel – 0.

After a trigger signal I see a valid TX burst on TX1 pin. But no signal on RX2 pin. RX2 pin stays low, also it should go high to VCC/2 according to the state machine.

What could be a problem?

  • 0
    TI__Expert 3350 points

    Can you please clarify what is the medium and how the transducers are aiming at each other (mounted on a pipe aiming at each other  through reflectors, mounted on a pipe aiming at each other directly,  etc) ?

    Thanks,


    B. Mirshab

  • 0 in reply to Bahram Mirshab
    Intellectual 430 points

    I think I found the problem. Chip doesn't get to Short TOF Measurement even if I set FORCE_SHORT_TOF it stays in Standard TOF Measurement .
    It always TRIGGER - TX BURST - RX GOES HIGH. In Short TOF Measurement it should be TRIGGER - RX GOES HIGH - TX BURST. So I think I miss the received signal cause TOF is very short.

  • 0 in reply to Evgeny Erenburg
    Intellectual 400 points
    Hi, I am also getting the same error with TDC1000-7200EVM for speed of Air measurement. My config : Two ultrasonic transducers (one for Tx and other one for Rx), 40KHz, Mode 1, Channel 0 tx1/Rx1. What could be the issue?
  • 0 in reply to Amit Deswal
    TI__Expert 3350 points

    If you have an oscilloscope available for use, please connect it to the EVM board as shown on page 11 of the attached document. With proper settings of no. of TX pulses, gain, and ECHO_QUAL_THLD, you should be able to see the ultrasound signal and the number of STOP pulses selected in the GUI on the scope display. If you do not get he signal, then one of the following could be the potential cause of the  condition you are experiencing:

    • The distance (the acoustic distance)  between the two sensors (if directed to each other using some kind of pipe or clamp mechanism) is too long, causing complete attenuation of signal before reaching the receiver transducer. (reduce the distance till you see the signal)
    • Sensors are not properly lined up to perfectly direct the pressure pulses at each other. (face the sensor directly at each other)
    • TX pulses peak-to-peak amplitude is not high enough for the transducers that you are using. (need to boost the TX pulses voltage externally to the level required by the sensor)

    snia020 (3).pdf