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Original question:

RTOS/TDA2PXEVM: How to set UB953 serializer register values?

DS90UB953-Q1: Clocking mode of Serializer UB953 while interfacing with AWR1243

Nishant G
Expert 1600 points

Part Number: DS90UB953-Q1
Other Parts Discussed in Thread: AWR1243

Hello,
I am planning to test the cascade AWR1243 radar satellite configuration for my application, i.e, 4 individual AWR1243, each connected to a serializer and connected to UB960 with FPD-LinkIII coax cable. For my testing, I am using AWR1243 Boost board and a customized daughter board with Serializer for interfacing. In the clocking mode operation mentioned in the UB953 Serializer datasheet, the recommended mode of operation is synchronous mode. The Deserializer UB960 has an reference clock of 25MHz while the reference clock used in AWR1243 boost is 40MHz. Hence, to operate this in synchronous mode, we will have to remove the reference oscillator of 40MHz from the AWR1243 Boost board and connect CLKOUT from the Serializer UB953 to XTALP pin of AWR1243 externally. Please correct if I am wrong or if you suggest any other method for synchronous operation.
I would like to not remove/alter the crystal oscillator present in the AWR1243 Boost. This would mean operating it in Non-synchronous mode. Now, according to the datasheet of UB953, there are two types of non-synchronous operation: Non-synchronous Clock mode with external oscillator and non-synchronous mode with internal Always ON (AON)  Clock. Does the internal Always ON Clock within UB953 Serializer give a stable frequency reference? Can I use Mode 3( i.e. non-synchronous mode with internal Always ON clock) for my satellite radar configuration? 
Thank you,
Nishant
  • 0
    TI__Genius 11340 points
    Hi Nishant,

    To run in synchronous mode, you just need the 25MHz reference clock to the 960. This will generate a forward channel rate of 4Gbps. Whether or not the system is running in synchronous mode is independent from the the AWR1243 reference clock. The AWR1243 can have a separate reference clock not provided by 953 clock_out.

    You should not run with internal Always On clock since it is not a stable reference.

    Best,
    Jiashow
  • 0
    TI__Guru** 116930 points

    Hello Nishant,

    The CLK_OUT of the 953 is not required to be connected to anything.  It is available if needed, but it looks like in your application, there is a local 40MHz reference, so you do not need the CLK_OUT. If you wanted, you could use CLK_OUT rather than the 40MHz reference, but it is not necessary.  

    In the Non-Synchronous with internal AON clock, the CLK_OUT cannot be used. – in any of the other modes, CLK_OUT can be programmed to be a clock source, but it’s operation is independent of the serialization that the 953 is doing.

  • 0 in reply to Hamzeh Jaradat
    Expert 1600 points

    Hello Hamzeh,

    Thank you for your reply. That's right, AWR1243 Boost board has a 40 MHz reference oscillator. But if I use this 40MHz at the radar sensor end, will I lose CSI-2 data packets while transferring it through UB953-UB960 Serializer-Deserializer link? Because the reference frequency at Deserailizer end is only 25MHz. Also, the reference oscillator of 40MHz is only for the sensor side(AWR1243 Boost board). So I was thinking of connecting an external oscillator of around 50MHz( since the datasheet of UB953 mentions that the external oscillator needs to be between 50-100MHz)  for the serializer UB953 and operate it in Non-Synchronous Clock mode with external oscillator because as Jiashow mentioned above, the Non-synchronous mode with AON does not provide a stable frequency and is unreliable. What do you suggest?

    Thank you!

    Best Regards,

    Nishant

  • 0 in reply to Jiashow Ho
    Expert 1600 points
    Hello Jiashow,

    Thank you for your reply. I had a follow-up question to the synchronous mode you mentioned above. From what I read online, for synchronous mode to operate, the sensor, UB953 and UB960 needs to work at the same frequency which is basically derived from the reference frequency from the Deserializer end, i.e, 25MHz. This is made by connecting the CLKOUT from UB953 to AWR1243 where CLKOUT provides the ref freq. Am I correct? Is there a way to ensure that the AWR1243 Boost board runs at 25MHz frequency even though it has a 40MHz reference oscillator and make the system work in Synchronous mode?

    Thank you,
    Nishant
  • 0 in reply to Nishant G
    TI__Genius 11340 points
    Hi Nishant,

    Synchronous mode just means that the serializer receives clock input from the deserializer to derive the forward channel rate. The sensor does not need to operate at the same frequency. The AWR1243 should be operating with the reference clock of 40MHz, which is what you have right now.

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    Expert 1600 points

    Hello Jiashow,

    Thank you for the clarification. If the sensor works is establishing the CSI-2 lane data rate of the four individual channels with ref freq of 40MHz and the serializer is establishing channel rate of 4Gbps using 25MHz reference frequency during synchronous mode, won't there be data loss due to the mismatch in the clock speeds? If yes, what do you suggest to prevent this problem?

    Thank you,
    Nishant

  • 0 in reply to Nishant G
    TI__Genius 11340 points
    Hi Nishant,

    The reference frequency of the sensor is independent from the CSI output of the sensor. You would need to look at the speed of the CSI output from your sensor, not its reference clock. As long as your total CSI input rate to the serializer is less than the forward channel rate (4Gbps if running at 25MHz synchronous mode), there will not be any data loss.

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    Expert 1600 points

    Thank you Jiashow for your reply. Could you tell me the reference document for setting up the CSI-2 output data rate from the sensor?

    Best Regards,

    Nishant

  • 0 in reply to Nishant G
    TI__Genius 11340 points
    Hi Nishant,

    Based on the AWR1243 datasheet, the CSI-2 data rate is scalable from 150Mbps to 900Mbps. Our UB953 can support up to 832Mbps per lane.

    I'm moving this thread to the AWR1243 team so they can better assist you with AWR1243 setup.

    Best,
    Jiashow
  • 0 in reply to Jiashow Ho
    TI__Guru 58035 points
    Hello Nishant,
    The Interface Control Document document (software-dl.ti.com/.../AWR1xx_Radar_Interface_Control.pdf ) lists the API to control the CSI o/p data rate from the AWR device.
    rlDeviceSetHsiConfig is the API that sets this configuration.

    Regards,
    Vivek
  • 0 in reply to Jiashow Ho
    Expert 1600 points

    Hello Jiashow,

    Thank you for your reply and for moving the thread to AWR1243 team! 

    Best Regards,

    Nishant

  • 0 in reply to Vivek Dham
    Expert 1600 points
    Thank you Vivek!

    Best Regards,
    Nishant