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TDC1000-GASEVM: TDC1000-GASEVM

Akshay.Shinde
Prodigy 60 points

Part Number: TDC1000-GASEVM

The mode 2 of the TDC1000-GASEVM does not work,

The channel that is selected in the drop down list (CH_SEL) continuously transmits and the other receives, there is no channel swapping observed even though the channel swapping (CH_SWP) is enabled using the GUI.

Initially, we thought it is a hardware issue and thus, bought a new board. But the issue still persists. We have also re-installed the TDC1000_7200 EVM GUI v1.2.7.1 (Rev. F) but it does not help.

All the signals were probed and it was observed that the TX pins, that is pin no. 27 and 28 of the TDC 1000 IC shows the existence of the 5V drive signal only at one channel based on the channel selected in the GUI, and the other channel shows 0 V, that is there is no swapping.

I would be highly obliged if you could help me resolve this issue.

  • 0
    TI__Genius 11015 points
    Akshay,

    I will check my system here & respond to you soon.
  • 0 in reply to Bharat Aravamudhan
    TI__Genius 11015 points
    Akshay,

    I see this issue in our setup, I am debugging on this and I will be back with you before the end of this week.
  • 0 in reply to Bharat Aravamudhan
    TI__Intellectual 1020 points
    Hi Akshay

    Can you please check one this on the GUI with the EVM connected.

    After you configure the device in the TDC1000 tab, In the debug tab can you read config_2 register which is address 2h. Use the section labeled as TDC1000 Register R/W.

    Regards,

    Vaibhav
  • 0 in reply to Vaibhav Garg10
    TI__Genius 11015 points
    Akshay,

    Please increase the EN period in the Setup tab to about 150us to make sure the EN pin is high post the START pulses.
  • 0 in reply to Vaibhav Garg10
    Prodigy 60 points

    Hi,

    I checked the register value it shows 0x12 for mode 2. Also in case of mode 1 and mode 0 it shows 0x11 and 0x10 respectively.

  • 0 in reply to Bharat Aravamudhan
    Prodigy 60 points
    Hi,
    I have already tried increasing the enable period on both the channels , it does not help.
  • 0 in reply to Akshay.Shinde
    TI__Intellectual 1020 points
    Hi Akshay

    Please make sure JP1 is connected per section 11.2 to get high voltage on both channels.

    Mode 2 is meant for flow metering where if TX1 is burst, the receive is on RX2. So you need to make sure in your setup you are seeing an echo received on RX2 transducer. Same for TX2/RX1 pair. Other wise there will be a timeout.

    Channel Swapping happens with every trigger. Please check trigger pin (Pin2 of JP5) to make sure trigger pulse in being generated.

    Also the EVM is designed for transducers between 58KHz and 300KHz. Please use one within that range.

    What is the end application that you are targeting with this EVM? Is it for Gas flow metering or some other application. I will suggest for gas flow metering applications please see the latest MSP430 device from TI: www.ti.com/.../overview.html

    Regards,

    Vaibhav
  • 0 in reply to Vaibhav Garg10
    Prodigy 120 points

    Hi,

    I checked the jumper JP1, it is conncted to HV. 

    And the board works for mode 1, also a channel swap can be done using the GUI while set to mode 1. But the automatic switching of channels which is expected in mode 2 does not happen.

    I have also checked the trigger pin (Pin2 of JP5) and observed the trigger pulse on the scope.

    The frequency being used is 200kHz which is within the range mentioned.

  • 0 in reply to Sonali Ellath
    TI__Genius 11015 points
    Hello,

    In mode 2 once the ToF is measured using the first transducer, then the channel will swap to the next transducer and again a ToF will be measured. Now in case you also use the averaging mode in Mode 2: a TOF measurement is done on one channel (direction) for every trigger pulse until the averaging count is reached. Also please check if 2 transducers are aligned to face each other & if one transducer receives the signal transmitted by the other transducer. Ensure if the transducer see the number of STOP pulses that it is expected to see. In case the number of required STOP pulse is not received the system will time out and no channel swap will occur.
    Channel swapping is controlled with the CH_SWP bit in the CONFIG_2 register. The EXT_CHSEL bit in the CONFIG_2 register must be 0 for automatic channel swap to work. If EXT_CHSEL is 1, the active channel selection is controlled manually with the CHSEL pin.
    As you are using a 200Khz transducer, please choose a CPU clock of 1.6Mhz and Frq_div of 8 as in the excitation pulse chart in the TDC1000-GASEVM user's guide.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 120 points

    Hi,

    The EXT_CHSEL is disabled using the GUI, (the value of the CONFIG_2 register is set to 0x12), thus the channel swap must be done automatically but this is not the case. Also the number of cycles (NUM_AVG) is set to 1 Cycle and the GUI is configured for a single STOP pulse.

    So the channel should switch after every trigger, but this is not observed.

  • 0 in reply to Sonali Ellath
    TI__Genius 11015 points
    Sonali,

    1. The Channel swap will occur once the device sees the first set of STOP signals received after the first transducer fires.
    2. Please check if you see any STOP signal post the first Tx from the first transducer.
    3. Send us Scope plot screen shot of START, STOP & the Tx/Rx of the transducers.
    4. In case you do not see any STOP signal please try the following
    A. Either increase or decrease the EACH_QUAL_THLD in the GUI
    B. Increase the NUM_Rx & NUM_Tx
    C. Check if there is any signal in the receive path of the transducer.
    D. Check if the transducers are aligned in such a way that the sound waves are directed properly.
    E. Increase the PGA_GAIN if the return signal from the transducer is very weak.

    Based on your question I assume you are using this device for Gas Flow Metering, we have another MSP430 based device which is designed for accurate liquid & gas flow metering: www.ti.com/.../description
    , please check this device & design.
  • 0 in reply to Bharat Aravamudhan
    Prodigy 120 points
    Hi,
    The stop pulse is generated, but the channel which was transmitting continues to transmit the 30 V pulses and the swap does not occur.
    Thus it works like it is in mode 1, though mode 2 is set in the GUI.
  • 0 in reply to Sonali Ellath
    TI__Genius 11015 points
    Sonali,

    If the expected number of STOP is generated then the device should swap the channels, I am not sure in which case this case cannot happen. Let me investigate further and get back with you on this.