• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 79 subscribers
  • Views 206 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

EVM430-FR6043: config_gas_400khz

Yale Li 李耀先
Expert 4660 points
Part Number: EVM430-FR6043

Hi Team,

The customer wants to change the transmission frequency to 500 through the default configuration of config_gas_400khz. But the front of the sampled waveform seems a bit strange:

--

Thanks & Regards

  • 0
    TI__Expert 6000 points

    Hello Yale,

    The possible reason may be that the "Number of Pulses" is too large which will make ADC get the residual oscillation. So you can let customer try to decrease the "Number of Pulses" to "12~16", and observe if the waveform is normal.

    Best Regards,

    Janz Bai

  • 0 in reply to Janz Bai
    TI__Expert 4660 points

    Hi Janz,

    Thanks for your reply.

    After changed the "Number of Pulses" to "16", the waveform is:

    Then changed to "12":

    Are these waveforms normal?

    --

    Thanks & Regards

  • 0 in reply to Yale Li 李耀先
    TI__Expert 6000 points

    Hello Yale,

    This signal looks good, but you still need to check your test environment. If you test in air, the amplitude is a bit small which means that if you used in other gas, the  test results will be very poor. You can try to adjust the test environment or hardware. 

    Best Regards,

    Janz Bai

  • 0 in reply to Janz Bai
    TI__Expert 4660 points

    Hi Janz,

    This is my customer's test environment:

    And dTOF's error is about ±2ns.

    It cannot reach the theoretical 400ps in the document, and the gap seems to be quite large:

    How do we adjust our test environment and hardware?

    --

    Thanks & Regards

  • 0 in reply to Yale Li 李耀先
    TI__Mastermind 32155 points

    Hi,

    Usually, we consider when the STD of dTOF lower than 1ns, the configuration is good enough for further tests. 

    You said the dTOF error is about ±2ns. At this point the STD(standard deviation) could be lower than 1ns. If so, customer should be okay to move on. 

    If the customer want to improve this result. First, it seems there is still some noise in the ADC capture signal. Try sealed the pipe on both sides and put the pipe in a metal case for testing. Also, connect the metal to the board GND with wire. It could help reduce the noise level and get a better dTOF result. 

    Best regards,

    Cash Hao

**Attention** This is a public forum