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AWR1243: AWR1243 cascade

HongJo Ahn
Prodigy 150 points
Part Number: AWR1243

Hello,

Q1]

From the AWR1243 document, 

Chip-to-chip cascading synchronization signals:
FM_CW_CLKOUT B15 O 20-GHz single-ended output. Modulated waveform
FM_CW_SYNCIN1 B1 I 20-GHz single-ended input. Only one of these pins should be
FM_CW_SYNCIN2 D15 I used. Multiple instances for layout flexibility.
FM_CW_SYNCOUT D1 O 20-GHz single-ended output for onboard loopback if desired
System synchronization:
SYNC_OUT P11 O Low-frequency synchronization signal output
SYNC_IN N10 I Low-frequency synchronization signal input.

a) What is the FMCW_SYNC signal and how different it is from the FMCW CLKOUT which is the actual FMCW chirp signal (ANALOG) ?

b) What is the SYNCIN signal running low frequency? I think it should be the one for frame and ADC sampling trigger but not sure. Is it from frame counter?

c) What is the SYNC (digital) related to FMCW_SYNC? 

Q2] What would be the sequence for the TX and RX on/off?

4-chip cascade example,

a) what is the sequence of TX and RX?

b) what is the maximum possible simultaneous TX ON, in one chip or chip1 and chip2 at the same time, etc?

Thank you so much.

Best regards,

  • 0
    TI__Guru 58035 points
    Hello HongJo,
    In general the AWR1243 device does not support cascading , you will have to use the AWR1243P device that allows cascading functionality.

    Please find my reply below:

    >>a) What is the FMCW_SYNC signal and how different it is from the FMCW CLKOUT which is the actual FMCW chirp signal (ANALOG) ?
    FMCW_SYNCOUT and FMCW_CLKOUT are both same SYNTH output signals at 20Ghz frequency (1/4th of the actual RF frequency at the TX). The reason two signals are provided is to ease routing if the other chip is on the opposite side, hence we provided two pins on both sides of the chip.


    >>b) What is the SYNCIN signal running low frequency? I think it should be the one for frame and ADC sampling trigger but not sure. Is it from frame counter?
    >>c) What is the SYNC (digital) related to FMCW_SYNC?
    Yes, this a pulse sent at the start of every frame. The transmitted frame is aligned with this signal edge. It has not relationship to the FMCW_SYNC


    >>Q2] What would be the sequence for the TX and RX on/off?
    >>4-chip cascade example,
    >>a) what is the sequence of TX and RX?
    >>b) what is the maximum possible simultaneous TX ON, in one chip or chip1 and chip2 at the same time, etc?

    There is no fixed sequence for the TX and RX of the 4 chips. You can enable any of the 12 TX/ 16 RX of the 4 chips. In the AWR1243P device there is no restriction on the number of simultaneous TX ON. All 12 TX can be ON simultaneously, you just need to take care that you are using the 1V RF supply mode and feeding the 1V at the VDD_PA_OUT pin as well. Other care abouts are the supply should be able to provide the required current for the 4 chips with the desired supply ripple (refer to the datasheet for peak currents and supply ripple requirements). Also the thermal heat needs to be dissipated appropriately so that the junction temperature does not go beyond 125C.

    Regards,
    Vivek
  • 0 in reply to Vivek Dham
    Prodigy 150 points
    Just GREAT!!! Thank you so much for your kind and detailed explanation + reference material! Two thumbs up!
  • 0 in reply to Vivek Dham
    Intellectual 385 points
    "In general the AWR1243 device does not support cascading"?? What about the X1243BIGABL engineering parts that I am debugging on my own cascade board right now? What do you mean by this statement? What problems should I expect (in case they are any of the ones stumping us right now)?
  • 0 in reply to DARIN
    TI__Guru 58035 points
    Hello Darin,
    The AWR1243 device will not support phase shifters and simultaneous 3TX operations which are typically needed in cascade operation. AWR1243P device is the one that would enable these features and is suited for cascade operation.

    Regards,
    Dham
  • 0 in reply to Vivek Dham
    Prodigy 150 points

    Hello,

    In the previous reply, I got a message from TI saying that AWR1243 evaluation kit would be available by the end of Q3 this year. Is it true?

    It seems Darin is already doing some tests with the kit. I also need cascade-able version which means AWR1243P according to recent reply.

    I could not find any information about it. Where can I find it and when would the evaluation/development kit available for this AWR1243? 

    Please let me (I am kind of so confused).

    Cheers,

    -Joel. 

  • 0 in reply to HongJo Ahn
    Intellectual 385 points

    Hi Joel,

    Just wanted you to know that I don't have a cascade development kit either.  We didn't have time to wait for it to be vetted, so I built my own.  That's why I am debugging the same problems that the TI team has probably already looked at.  I thought that I saw in another post that the AWR1243P part would be out early next year, so we are likely without the phase shifters and 3TX operation until then.

    Darin

  • 0 in reply to DARIN
    Prodigy 150 points
    Hi Darin,
    Thank you for your kind clarification. Now I understand what was going on and it makes perfect sense.
    Thank you again!