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OPT8320 Time of flight sensor

Expert 1140 points
Other Parts Discussed in Thread: OPT8320

hai ,

we have designed a new product using opt8320.We are not able to properly interpret the data provided by the opt8320 time of flight sensor? What is the actual meaning of the saturated and non saturated values given by opt8320 sensor? Which one is the actual data? What is the actual difference between them?

How will the different modes like indoor gesture outdoor gesture influence the values read by the opt8320 sensor? How should we adjust the lens position to get the correct information?We are presently operating it in slave mode. And how should be make use of the estimator tool specified in the datasheet of the opt8320 time of flight sensor?

please if someone could help me regarding this...........

  • The amplitude image represents reflected amplitude, not ambient amplitude.  Reflected light are modulated light originating from the sensor's illumination.  Ambient image shows in-band (850 nm) environment light.  During saturation, the ambient image will have low value (lower the value, higher the ambient), and the saturated area in the amplitude image will turn dark (at or near 0).

    Outdoor operation means sensor will see more ambient light.  Higher the ambient light, less the AC contrast, that means the amplitude will reduce.  To reduce ambient influence, try increase the number of sub-frames, reduce integration duty cycle, while increasing illumination power.

  • hai larry,
    your information helped me a lot and thanks for that.But i am also facing issues when i receive frames in opt8320.when i configured opt8320 in slave mode and after getting frames of about 100-400 numbers randomly ,right after giving VD_IN, the pulse seems to be waiting for VD to be high , which means the pulse isnt getting any VD pulse as response .What could be the possible reason behind this? And can you please tell me how should i interpret the data which i got from opt8320? How can i confirm the data i obtained from opt8320 is correct?
    Please help me with these doubts too.
  • Capture is initiated on rising edge of VD_IN.  So, VD_IN must have a falling edge followed by another rising edge to trigger capture of a second frame.  VD_IN pulse width must be minimum of 2*SYSCLK.

  • hai larry,
    we are following the same steps(first giving a VD_IN pulse and waiting for VD pulse).
    and still our doubts prevail...how to confirm the data which we obtained from the opt8320 is correct or not?
  • This is a known issue with OPT8320.  Solution is to use a latch to synchronize VD_IN to SYSCLK.   Say your "snapshot" signal is VD_Strobe, feed it into a latch that has VD_IN as output.  VD_IN should latch VD_Strobe at the rising edge SYSCLK.  Now make sure VD_Strobe is at least 3 * SYSCLK long.

    One way to verify data is to make sure delta phase is linearly proportional to delta distance.

  • Hai Larry,

    i really don' t know how to thank you for these responses.Thanks a lot for that.

     Those helped me a lot in my project.let me share our setup for testing with you.You can see that in the image attached with this.the first pic shows a box with some pattern created in it.

    we just wanted to know the actual response of the opt8320 sensor.We then placed the opt8320 sensor pcb into the box and obtained a set of values.We then extracted the amplitude data from the 32 bit pixel data which we obtained from opt8320.We later copied the amplitude data into an excel sheet and with the help of conditional formatting color scales option, we colored the data.

    The data is being colored in a format such that , red color corresponds to amplitude zero ,peak values  green and an intermediate values are represented by yellow.

    i have attached those excel sheet pics too.

    the major doubt i have is that, why are we getting the value zero? Is it due to poor illumination or is it due to something else?What do these values ranging from zero to 4000 and above mean actually?Really what does this value zero actually mean?

    can you please help me regarding these doubts too.

  • Amal,

    It looks like you're making good progress, the raw data looked correct, but they are interleaved (and they should, indeed).  Zero amplitude can come from pixel saturation or very low illumination. Given your setup in the picture, pixel saturation due to close distance is more likely.  For debugging, it is best to separate out the pixel's amplitude, phase, ambient and flag into separate images; otherwise it will be very hard to see what's going on.   Our Voxel SDK unpack the various image types for you.  If you're not using it, you can still see how it is done.

  • Hai Larry,

    Thanks a lot for you supporting replies,i would like to know how to interface our sensor board to Voxel viewer, how can we do this or is there any other option to view our data(or the data consisting of amplitude, phase,ambient separately). Is there any other software's available to do this.

  • Voxel Viewer works with Voxel SDK to get the ToF data.  Voxel SDK currently supports FX2 and Realtek USB controller.  FX2 is used in our OPT8320 CDK.  For your system you need to modify Voxel SDK to get the data into the Voxel SDK.  After that, Voxel Viewer will be able to call Voxel SDK to get data into the GUI for display.