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TDC1000-TDC7200EVM

Randy Adams80
Intellectual 345 points
Other Parts Discussed in Thread: TDC1000, TDC7200

I have the TDC1000-TDC7200EVM connected to the PC.  I have two 1 MHZ transducers connected to the TDC1000-TDC7200EVM.

I put the transducers on a pipe across form each other and I get 37,700 us.  If I shake the water the graphic moves. 

First

If I remove the transducers the graph stays at the 37,700us.

Second

When I connect my scope as shown in the setup.  I get nothing!

Can anyone help with getting this reading?

Randy

  • 0
    TI__Expert 4725 points

    Randy,

    Without seeing your setup I can't help debug your issue. Please answer a few questions so we can help.

    1.What are you trying to accomplish? What is your application?

    2. What do you mean by "you've connected as shown in the setup"? Are you referring to a specific figure? If so what document are you referring to?

    -regards,

  • 0 in reply to Matthew Minasi
    Intellectual 345 points
    I am trying to determine the TOF using the TDC1000-TDC7200EVM. My application is a ultrasonic water meter. I am referring to the EVM user guide. Figure 5-6 on page 13. And Figure 5-7 on page 14.
  • 0
    TI__Expert 3350 points

    Hi Adams,

    Apparently the ultrasonic pulses are not penetrating through the pipe material, or there is too much diffraction of the signal at the acoustic boundary between the pipe material and the medium in the pipe.

    I assume you are experimenting to make a clamp-on ultrasonic flowmeter. If that is the case, you should put the sensors across the pipe at an angle of typically 45 degree. The transducers must be secured to the pip such that there is no air gap between the entire surface of the transducer and the  surface of the pipe. The distance between the sensors should be at least 60 mm. The transducers must be facing each other precisely such that the beam of each transducer is perfectly aligned with the other. Otherwise, there would be a large delta-TOF offset error.

    Depending on the materiel of the pipe, the distance between the two transducers, and the type of medium in the pipe, much higher  than 3.6 V transmitter pulses generated by the TDC1000-TDC7200EVM board my be needed.

    Regards,

    Bahram. Mirshab

  • 0 in reply to Bahram Mirshab
    Intellectual 345 points
    I understand this but if I use petroleum jelly and stick the tow together I should get a signal. I don't!
    There is nothing I can do to get a signal on the scope. The graph reacts but I don't think it is correct. I need to check it with the scope.
  • 0 in reply to Randy Adams80
    TI__Expert 3350 points

    Hi Randy,

    What is the pipe material, diameter and the medium inside the pipe. Is the sensor glued to the pipe's curvature or you have sanded the contact area to a flat surface. Can you please let us know what  parameter in this  experiment you are trying to measure; medium velocity, medium concentration, etc.

     

    Thanks,

     

    B. Mirshab 

  • 0 in reply to Bahram Mirshab
    Intellectual 345 points
    Right now I am just trying to get it to READ! I get nothing. If I just take the sensor (1) and sensor(2) and put them touching with the petroleum jelly I should get a reading on the o-scope. I don't get anything out on the scope. Until I get a signal I can't read anything.
    I am trying to read the medium velocity.
    I had a Acam chip and was getting a good signal from it on there board but came over to TI. so I know what I should read.
  • 0 in reply to Bahram Mirshab
    TI__Expert 3350 points
    Hi Randy,

    If you get the signal using ACAM, then you should get the same result or better with the TI EVM as TDC1000 has on-chip gain stages to amplify vey small echo through the media. This feature does not exist in the ACAM. Please check the TX and RX signals using your scope at the connector to make sure that there is no open sensor condition. If that is not the problem, make sure that TDC1000 and TDC7200 registers are set correctly in the GUI.

    Regards,

    B. Mirshab
  • 0 in reply to Bahram Mirshab
    Intellectual 345 points

    I am getting signal now on the scope. It is all over the place, I can not measure the time on the scope as in the evm manual. I wanted to verify the time on the software before I proceeded. Can you tell me what the graph is reading when I check the box Flow?
    Thanks
    Randy

  • 0 in reply to Randy Adams80
    TI__Expert 3350 points
    The graph is reading delta-TOF , that is "Tu - Td" when the flow box is checked.

    b. Mirshab
  • 0 in reply to Bahram Mirshab
    Intellectual 345 points

    I received your paper from Michael on the flow meter and it gave me a lot of information on the software.  I have the scope waveforms now.  But I did have a bad solder connection on the EVM board right at the probe connector for stop.  My problem now is that I only get start on Mode 2 everything else goes away.  D2 and D3 blink alternately.  Any ideas? 

  • 0 in reply to Randy Adams80
    TI__Expert 3350 points

    Randy,

    Glad to hear that you have got passed the last hurdle, thanks for your patience.  Michael will contact you by phone to pass to you my instructions to help you with your experiment.

    Regards,

    B. Mirshab

  • 0 in reply to Randy Adams80
    TI__Expert 4415 points

    Hi Randy,

    I have discussed with Bahram and Michael and have a couple of suggestions. Mode 2 is the flow rate (delta TOF) measurement mode, and D2 and D3 should blink alternately to show that the board is transmitting pulses, so that is operating as expected. On the hardware side, I would double check to make sure all the jumpers are set as described in the guide (which I am reattaching for reference). Then, in the GUI, double check that CH_SWP is set to Enabled under the TDC1000 tab. Finally, if the results are not graphed in the GUI, right click the graph and autoscale the axes to make sure it isn't just out of range.

    snia020.pdf


    If the setup is still not working, I will also attach a known working configuration file that can be loaded into the GUI for you to try. Although it is known to work with our setup, there are still a couple of options that may need to be changed. Since transducers and the interfaces on which they are mounted will vary, the amount of amplification of the received signal must be changed to suit each application. After loading the file, under the TDC1000 tab, under TOF-1(0x05), the PGA_GAIN, PGA_CTRL, LNA_CTRL registers must be set so that the COMPIN signal you see on your scope (e.g., the received signal after it has passed through the PGA and LNA) is strong and clean. Too low amplification and it can't be read (e.g., won't pass the comparator threshold for STOP pulses to register), but too high and you will get distortion and inaccurate flow results. I would try leaving LNA_CTRL to 'bypass' at first, then try turning up the PGA_GAIN to see if that gives a usable result before setting LNA_CTRL to 'enable' and again changing PGA_GAIN.


    Fullscreen tdc1000_flow_testsetup.txt Download 
    TDC1000_Config0                         48
TDC1000_Config1                         45
TDC1000_Config2                         12
TDC1000_Config3                         0B
TDC1000_Config4                         0E
TDC1000_TOF-1                           A8
TDC1000_TOF-0                           1F
TDC1000_Error_Flags                     00
TDC1000_Timeout                         21
TDC1000_Clock_Rate                      02
TDC1000_Conts_Trigger                   01
TDC7200_Config1                         02
TDC7200_Config2                         44
TDC7200_Interrupt_Status                07
TDC7200_Interrupt_Mask                  07
TDC7200_Coarse_Cntr_Ov_H                FF
TDC7200_Coarse_Cntr_Ov_L                FF
TDC7200_Clock_Cntr_Ov_H                 FF
TDC7200_Clock_Cntr_Ov_L                 FF
TDC7200_Clock_Cntr_Stop_Mask_H          00
TDC7200_Clock_Cntr_Stop_Mask_L          00
TRIGGER_UPDATE_FREQ                     0009
TDC_AVG/STDEV_NUM_ELEMS                 0002
SAVE_GRAPH_DATA_TO_FILE                 00
FLOW_MODE_SELECT                        01
Y-SCALE_CENTER                          0000
X-SCALE_RANGE                           0000
MEASURE_RTD1                            01
SAVE_RESULT_REGR_TO_FILE                00
GRAPH_MULTI_STOPS                       00
TDC_SELECT                              02
TEMP_RTD_SELECT                         00
TEMP_RTD_MODE                           01
TEMP_AVG/STDEV_NUM_ELEMS                000A
SAVE_TEMP_DATA                          00
GRAPH_YMAX_DATA                         0000000000000002
GRAPH_YMIN_DATA                         0000000000000000
TDC1000-HV_DRV_EN1                      00
TDC1000-HV_DRV_EN2                      00
HV_DRV_EN1_Period                       001E
HV_DRV_EN2_Period                       001E
ENABLE_POWER_CYCLE                      00
CLK_FREQ_(1-16MHz)                      8.000000
CLK_SOURCE_SEL                          00
CPU_CLK_FREQ                            05
CPU_CLK_EN                              00
TDC1000-HV_BST_PWR_EN                   00
HV_BST_PWR_EN_Period                    000F
FWD2REV_FLOW_DELAY                      0000
TDC1000-IMPE_MATCH_EN                   00

    Let me know if these suggestions work for you or if you have any additional questions.

    Regards,

    Tim

  • 0 in reply to Bahram Mirshab
    Intellectual 345 points
    I have the unit reading a signal. (working) I am getting all the pluses out the scope that I should.
    Let me preface my question by saying. I have a known good sensor setup. It is from a name brand company.
    I wanted to eliminate an unknown. I have a known good config file in place and reading time on the graph.
    This time varies with my pump flow.
    Now for the problem: My pump should give anywhere from .5 to 3 GPM.
    My TOF delta is 3.5us to 9us varying. My distance of the sensors are 35.32mm=.03532m Pipe ID 20mm Temp is 21.7C v= at that temp is 1481
    Using v=(C^2/2L)*delta t I get (1481^2/(2*.03532))*3.5*10^-9=.00109m/s^3
    Converting to GPM .00109*15852=17.384GPM?
  • 0 in reply to Randy Adams80
    TI__Expert 3350 points

    Hi Randy,

    Set the flow to zero on the pump. In the GUI, in the flow mode (see the attached guide to connect a flow sensor to TDC1000-TDC7200EVM) read delta-TOF in the Graph menu.  If the transducers are matched perfectly, at zero-flow depending on the mismatch of the transducers, the delta-TOF reading should be about 80-300 ps  with standard deviation of about 30-200 ps (with about 64 delta-TOF average). In the GUI's graph menu select a STOP pulse (1,2,3,4, or 5)  for measuring TOF that gives you the best result . Most likely you would read a delta-TOF of a couple of ns  and a standard deviation of about 400 ps. This offset error is due to the transducer mismatch, and to some extend,  due to the unsymmetrical impedance in the TX/RX path (read Apps note SNIA020 attached). The standard deviation is due to random noise in the system and can be reduced by averaging. You need to calibrate this offset at each reading to get correct results.

    Regards,

    B. Mirshab

     Interfacing a water flow sesnor to TDC1000-TDC7200EVM-022715.pdfsnia020 (1).pdf

  • 0 in reply to Bahram Mirshab
    Intellectual 345 points

    The problem was in my calculation to convent to GPM.  Now I have the calculations correct, I am have a second problem.

    To get the correct and constant GPM to display I must double the delta TOF number minus the static number on the graph.

    Why?  This works and is constant over .25 GPM to over 10 GPM.

    Randy Adams M.S.E.

  • 0 in reply to Randy Adams80
    TI__Mastermind 25990 points
    Randy
    Bahram is travelling this week. I will send a friend request to see how I can help.
    Chuck