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AFE7920: Multi-device sync

JONGROH YOON
Prodigy 50 points

Part Number: AFE7920

Hello.

We are developing a Beamforming system using four AFE7920s.

After the initialization of the first AFE7920 is complete, we proceed with the initialization of the second AFE7920.

We perform the initialization of the four AFE7920s in this sequence.

In this case, I anticipate that phase will vary each time we perfom initalization. (becase of clock divider  sync, nco sync...)

We have confirmed that the phase also varies during testing.

Questions are

1. Should I use the Single Shot sysref method to synchronize the phase of Multi AFE7920?

2. If Single shot sysref method must be used,

       Which part of the latte script should I insert the Pin sysref? (The Initialization Flow for Single Sysref in the datasheet indicates two instances of "Give Pin Sysref".)

       How can I generate script for "single shot sysref method"?

3. If Single shot sysref method must be used,

     Is it possible to synchronize the phase by generating one instatnce "Give pin sysref" after initializing all AFE7920?

4. If continose shot sysref method can be used for this system.

     What parameter or seqence should I change ?

 

Thank you

Jongroh Yoon

  • +1
    TI__Guru* 81495 points

    Hi Jongroh,

    Please advise for the RX and TX frequencies amongst the multiple AFE7920s needing relative phase synchronization or absolute time synchronization. 

    Relative phase synchronization means the phase difference between TX and RX need to be aligned. The phase difference can be arbitrary marked at any point in time, and as long as the delta between the two output (or input) are zero, relative phase difference can be achieved.

    Absolute time alignment means the "starter" phase of one channel need to align with "starter" phase of another channel. The starter time marker is marked one at the beginning. Since the beginning in time, the phase and also time delta between the channels have to be the same.

    Per our understanding of typical wireless basestation setup, only relative phase synchronization is needed. For example, for antenna beam forming calibration, as long as the "relative" phase amongst the channels are calibrated, then the beam forming can be performed.

    In such relative phase alignment, the following three methods can be used:

    1. single shot method:

    2. continuous sysref with GPIO capture of the synchronization source:

    3. The RXNCO and TXNCO are set to be integer multiple of continuous SYSREF frequency. Each cycle of the TXNCO and RXNCO are reset and aligned with the SYSREF frequency.

    Some additional information can be found in the following TIDA

    https://www.ti.com/tool/TIDA-00996

  • 0 in reply to Kang Hsia
    Prodigy 50 points

    Hi Kang.

    I have some question about your suggestion.

    1. Single shot  sysref method

        which API can I use to  execute "Sysref Latch enable" ?

    2. Continuous sysref method

          "SYSREF Latch enable" is not in the list of supported input function in "AFE79XX_Configuration_guide.pdf".

         Does  "SYSREF Latch enable" mean "ADC_SYNC0/1/2/3 and DAC_SYNC0/1/2/3"?

    3. You must be a genius. 

        I'm going to use this method in this project.

        If I have some trouble in testing,  I'll ask some question again.

    Thank you very much.

    Jongroh Yoon    

  • 0 in reply to JONGROH YOON
    TI__Guru* 81495 points

    Hello Jongroh,

    JONGROH YOON said:
    which API can I use to  execute "Sysref Latch enable" ?

    SYSREF Latch Enable may be a new function that we need to add for the C API library. We will need to follow-up and get back to you.

    JONGROH YOON said:
     Does  "SYSREF Latch enable" mean "ADC_SYNC0/1/2/3 and DAC_SYNC0/1/2/3"?

    No, It does not mean ADC_SYNC and DAC_SYNC.