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CC3200 ADC time stamp accuracy

Sai Kwok
Prodigy 200 points
Other Parts Discussed in Thread: CC3200

I have a question regarding CC3200 ADC time stamp.

I am using two CC3200 and need very accurate ADC time stamp between the two devices. Clock sources are temperature compensated, time drift is less than 0.5 mili second after 10 minutes. 

Is time stamp accuracy totally dependent on clock source? Will we get the same 0.5 mili second time drift after 10 minutes? Please advise.

Thanks

BTW: What is "Select Tags" for?

- Sai Kwok

  • 0
    Prodigy 200 points

    I have another question.

    CC3200 ADC data sheet shows 2 usec sampling for each channel

    Assuming there is no external RC time constant, could you please send me time response of sampling? Is sampling completed in 2 usec? Please advise.

    Thanks.

    Sai Kwok

  • 0 in reply to Sai Kwok
    TI__Genius 11120 points

    The ADC takes 4 clocks of 10MHz to complete the sampling.

    So the sampling time = 4 x 100ns = 400ns. The internal capacitor gets charged in 400ns. This is not the conversion time.

    The 2us shown is for the sampling + conversion for each ADC channel. There are 8 such channels for the ADC. So the ADC will come back to a channel after 2x8 us = 16us

    This provides the sampling frequency possible per channel = 1/16 us = 62.5KHz.

     

    to summarize

    > Sampling time (Time taken by internal cap to charge) = 400ns

    > Sampling frequency (No of samples per second for one channel) = 62.5 KHz

  • 0 in reply to Prajay Madhavan
    Prodigy 200 points
    Thanks for explanation. Do you please send me link on more CC3200 ADC info.

    I am going to take one sample every 16 x 5 = 80 us. This is equivalent to 12.5 kS/s.

    This allows me 78 usec to take care of other tasks.

    How many bits is time stamp?

    I would like to take time stamp immediately after sampling. How long does it take after 2usec for time stamp?

    Thanks.
  • 0 in reply to Sai Kwok
    Prodigy 200 points

    We need accurate TCXO clock. 

    38.4MHz is significantly less expensive than 40MHz. What is performance impact with 38.4MHz? Please advise.

    Thanks.

  • 0 in reply to Sai Kwok
    Prodigy 200 points

    I have another question regarding CC3200 FCC status.

    Has this chip set been FCC approved?

    How do we implement design to take advantage of FCC certification? Please advise.

    Thanks.