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Input to the BCP module

santosh kumar panda
Prodigy 165 points

Hi ,

 The Information bits(i.e payload) which is given to the BCP for processing whether includes the TB CRC ? 

  • 0
    TI__Intellectual 1585 points

    Santosh,

    I'd suggest looking at the BCP user guide (http://www.ti.com/lit/ug/sprugz1/sprugz1.pdf). Look on page 42, which has an example packet. It shows how the TB CRC is attached on page 26 and 27 as well. 

    I hope this answers your question!

    Kat Kelsch

  • 0 in reply to Katherine Kelsch
    TI__Mastermind 30405 points
    Thanks Katherine,

    Santosh,

    I assume this question relates to Downlink where the BCP input is a TB which normally does not have the TB CRC and BCP handles CRC generation. This step is optional and you can configure the BCP to bypass TB CRC generation as per your application needs.

    Regards

    -Nitin

     

  • 0 in reply to Nitin Sakhuja
    Prodigy 165 points

     Nitin,

    I got a default test case provided by TI in which the infobit(i.e Payload) is tbsize+6byte . But we assume that the input to crc should be tbsize only. Can you tell us what is that  6byte is ? Is it 24a crc or it is added for 128bit alignment ?

     The path where we got the infodata along with configuration file is : C:\ti\pdk_C6670_1_0_0_21\packages\ti\drv\bcp\test\lte\pdsch_inforBits_0002.dat

    And one more concern if we comment out  the crc header formation during packet creation then BCP will by pass CRC?

    Regards,

    Santosh

  • 0 in reply to santosh kumar panda
    TI__Mastermind 30405 points

    Santosh,

    Sorry for the late response.

    1. Due to an issue with Rev 1.0 of C6618/C6670 silicon, the CRC sub-module can lock-up and therefore is cosidered non-functional in these devices, which is why there should be 3 extra bytes in the BCP input in the PDK test which does not use the CRC sub-mmodule and assumes CRC calculation in software. This issue is listed in Advisory 17 (BCP CRC Failure Issue) of the TCI6618 SoC Errata available at http://www.ti.com/litv/pdf/sprz352c.

    2. Padding is required only after the BCP Header to make it 128-bit aligned. This padding is needed since BCP expects the payload to start at the next 128-bit Quad-Word boundary. However, no padding is needed after the payload, so the other 3 extra bytes you see must be a part of the payload.

    3. Yes, removing the CRC header will cause the BCP to skip CRC sub-module and hence all functionality associated with it. Please make sure to update the Hdr_end_ptr in BCP global header as the header size will be reduced. I believe the PDK test already excludes the CRC sub-module as CRC is already attached in the payload input to the BCP.

    Regards
    -Nitin

  • 0 in reply to Nitin Sakhuja
    Intellectual 485 points

    Can help on this problem?

    http://e2e.ti.com/support/dsp/c6000_multi-core_dsps/f/639/p/293538/1025864.aspx#1025864

    Thanks very much  in advanced!

    Alan