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c6678 SRIO is Full-duplex ??

si cheng
Expert 2685 points

hello :

I am using SRIO, and I wan to know the SRIO is Full-duplex OR Half-duplex?

I know the most bandwidth of SRIO is 5Gbps*4 = 20Gbps, the 20Gbps is the Sending speed, 

1 . if the SRIO is receiving data at the same time it sending data  , the SRIO bandwidth should be 20Gbps*2= 40Gbps,  Is it right?

2 if SRRIO is sending  data and at the same time , it is receiving data from other DSP,  Is the  Sending speed still 20Gbps?

will  the receiving operation affect  the Sending Speed ? if  the sending operation and the receiving operation are independent?

Thanks

  • 0
    TI__Guru* 84110 points

    Si Cheng,

    As I see it, each SRIO lane is a Rx + Tx pair so they will be full-duplex. The RapidIO Standard is the place to find this definition.

    The two directions are not totally independent because some transactions require a response sent on the other pair. For example, some WRITE commands require an acknowledgement or other response packet, and the NREAD command sends the command on the Tx pair but the data returns on the Rx pair.

    So the definition of full-duplex may be set by the RapidIO Specification.

    In general, yes, you will get the full data transfer bit rate potentially on both Rx and Tx lines simultaneously.

    Regards,
    RandyP

  • 0 in reply to RandyP
    Mastermind 7395 points

    Additionally, for any SRIO speed there is an 8/10 encoding scheme involved, so the maximum raw bandwidth on each direction, per line, would be 2.5Gbps for 3.125Gbps signaling, and 4Gbps for 5Gbps signaling.

  • 0 in reply to Avi Chami1
    Expert 2685 points

    Thanks for everyone.

    I know that the WRITE command has  witte with respnose(NWRITE) and write without response(NWRITE_R).

    1. if my transfer is NWRITE, how can I know I have transferred over, Because without no response. 

    2 .above case ,I know I have transferred over ,  whether the external PE has already received my sending data simultaneously???Because it is NWRITE

    3. if I use NWRITE_R command to transfer data, and the external PE is transferring data to me with NWRUTE_R simultaneously, all at 5Gbps ,4X , and 

     I wil receive response from the external PE before the external PE receive reponse from me, during this period, I am receiving reponse from the external PE,

    and the external PE is transferring data to me.

    I want to know if  I  will  receive response after the the external PE transfer over, Because  my Rx is receiving data, and the external PE's TX is sending data, they

    are all busy, the external PE can not response righ now!

    Thanks!



  • 0 in reply to si cheng
    TI__Guru* 84110 points

    Si Cheng,

    Please look over your post above. I believe some terms are swapped, and this makes me unsure what you are describing.

    I think you need to refer to the RapidIO Specification and their documentation to understand how SRIO handles conflicts and sharing. This is not a TI-proprietary protocol but an industry standard one.

    My guess is that the right answer for you is that the SRIO allows for conflicts and will handle them appropriately to make sure all the data and responses are sent. You may monitor the error conditions of the SRIO to determine if any transfer failures have occurred.

    Regards,
    RandyP