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AWR2243: Error code 66 with manual VCO select

Tegan Counts
Prodigy 20 points
Part Number: AWR2243

I'm getting an error code 66 that I believe to be a mistake. It appears to be using the VCO1 limits even though I'm manually forcing VCO2. Here are the setup conditions:

  • Advanced frame
  • Legacy chirp
  • 1 profile
    • Manual VCO selection of VCO2 using AWR_PROFILE_CONF_SB
  • 1 subframe
  • 2 bursts

  1. Burst 1
    1. Start freq: 77.8 GHz
    2. End freq: 77.95 GHz (end freq = chirp slope * ramp end time)
  2. Burst 2
    1. Start freq 77.95 GHz
    2. End freq: 78.1 GHz

After much experimentation, here is what we suspect:

  • The internal VCO selection algorithm appears to only use the first burst of the subframe, thus selecting VCO1
  • The error code 66 logic uses the internal VCO selection to set freq limits, thus selecting 76-78 GHz
  • When burst 2 crosses over 78 GHz, the error code is thrown
  • 0
    TI__Mastermind 30545 points

    Hello Tegan,

    I just tried reproducing this on the EVM (note:this was tested on single chip EVM, but for this experiment I don't think that should have an impact). Attached are the images of my configuration. I did not see any error trigger during framing. 

    1 profile with two chirps, second chirp has 150MHz start frequency offset. VCO2 selection is forced:

    2 bursts with second burst having chirp start index offset of 1 to use the second chirp:

    Can you please confirm which firmware version you are using?

    Regards,

    Adrian 

  • 0 in reply to aozer
    Prodigy 20 points

    AWR MSS Version: 7/29/20 2.2.2

    AWR RSS Version: 7/6/22 2.2.4

    AWR mmwlink Version: 8/13/20 2.2.2

    I analyzed your parameters above, and they look good. Tonight I will go through a detailed comparison of every value and get us as close as possible.

    If you don't force the VCO to 2, would you get an error code 66?

  • 0 in reply to Tegan Counts
    TI__Mastermind 30545 points

    Actually, if I do NOT force the VCO select then I see error code 66 when trying to configure the second chirp that exceeds the 78GHz range.

    So, it seems like the firmware will default to VCO1 in this case since the profile BW is below 78GHz. It seems like maybe your force VCO select is not taking effect.

    Regards,

    Adrian

  • 0 in reply to aozer
    Prodigy 20 points

    We agree that the problem might be that we aren't forcing the VCO selection as we think we are. 

    Also, we have some slightly different parameters in our waveforms. I do not suspect this to be this issue, but just in case:

    • Slope: 7.5 Mhz/us
    • ramp end time: 20 us
    • idle time: 2 us
    • adc start time: 6 us
    • adc rate: 20 MHz
    • tx start time: 0 us
    • num adc samples 256

    I've tried multiple times to upload binary blobs that are the profile and frame sub blocks we are sending, but the e2e interface won't allow them to upload. The purpose would be to compare against what binary you're sending for those sub blocks. Is there another trick within the e2e tool by which I can get them to you?

  • 0 in reply to Tegan Counts
    TI__Mastermind 30545 points

    I looked at the .bin file, it does not seem like VCO select is being applied. I see a value of '00' indicating that both the FORCE_VCO_SEL and VCO_SEL bits are being set to a value of zero.

    Regards,

    Adrian

  • 0 in reply to aozer
    Prodigy 20 points

    With this, I was able to discover a bug in our binary payload generation! Problem resolved. Thank you.