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Minimum level possible to measure with TDC1000-TDC7200EVM

Matheus Costa
Prodigy 80 points


Hello, I'm having problem with the level measurement in the TDC1000-TDC7200 EVM. I'm trying to masure water level in a acrylic tank where the piezoelectric sensor is placed under the tank. But whe I start to measure, the tank level in the screen of the software starts in 2,7cm without water, and just change the level when it is over 3cm.

could anyone help me with this problem? this is some lower limit of the software or I may be doing something wrong?

  • 0
    TI__Genius 11015 points
    Matheus,

    Please place a highly reflective lid on top side of the tank when there is no water and see if the device see it.
    At time the transducer may pick up reflective signal from the side walls as well and then provide erratic data.
    Try also to re-position the transducer such that is it oriented properly to receive the return signal post reflection.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 80 points

    Thanks for the answarer Bharat,

    But I alredy made this test with the reflective lid in the top, and the TOF that the transducer presents without liquid in the tank is around 37620ns, with and without the reflectie lid. I do not think that the walls of the tank are making interference on the measure, because the value present is up than any distance of the walls. I also tried to put the transducer placed in a thicker wall and the measure continued the same. And the strange thing is that the measure start to make sense when I put liquid in a level over 3cm.

  • 0 in reply to Matheus Costa
    TI__Genius 11015 points
    Matheus,

    Please send me the registry setting, the device may have to be placed in short TOF for a shorter distance.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 80 points

    This are the registry setting that I'm using to get the information of the sensors. I tried to use the short distance configuration once, but the answer seems the same. The sensor is a 1MHz piezoeletric.

    Fullscreen TDC1000_Setup.txt Download 
    TDC1000_Config0                         41
TDC1000_Config1                         00
TDC1000_Config2                         00
TDC1000_Config3                         05
TDC1000_Config4                         00
TDC1000_TOF-1                           03
TDC1000_TOF-0                           FF
TDC1000_Error_Flags                     00
TDC1000_Timeout                         1B
TDC1000_Clock_Rate                      01
TDC1000_Conts_Trigger                   01
TDC7200_Config1                         00
TDC7200_Config2                         00
TDC7200_Interrupt_Status                00
TDC7200_Interrupt_Mask                  00
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                     0001
TDC_AVG/STDEV_NUM_ELEMS                 000A
SAVE_GRAPH_DATA_TO_FILE                 00
FLOW_MODE_SELECT                        00
Y-SCALE_CENTER                          0032
X-SCALE_RANGE                           0032
MEASURE_RTD1                            00
SAVE_RESULT_REGR_TO_FILE                00
GRAPH_MULTI_STOPS                       00
TDC_SELECT                              00
TEMP_RTD_SELECT                         00
TEMP_RTD_MODE                           01
TEMP_AVG/STDEV_NUM_ELEMS                000A
SAVE_TEMP_DATA                          00
GRAPH_YMAX_DATA                         00000000000091BC
GRAPH_YMIN_DATA                         000000000000918E
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                    0000
FWD2REV_FLOW_DELAY                      0000
TDC1000-IMPE_MATCH_EN                   00
ENABLE_UART_STREAM                      00
ENABLE_MSP430TIMER_TDC                  00

  • 0 in reply to Matheus Costa
    TI__Genius 11015 points
    Matt,

    Please send me the screen shot of the START/STOP Pulse, TX/Rx pin, COMPIN Pin and signal at R34(PGA output) in the EVM.
  • 0 in reply to Bharat Aravamudhan
    TI__Genius 11015 points
    Matt,

    Please ensure you have enabled the short time of flight and then increase the short TOF blank period for water levels less than 3cms.
    Also monitor the TOF measurement in the graph tab to check you get the expected TOF.