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S800 transmissions with 1394 PHY TSB81BA3E

Harold Okai-Tettey
Prodigy 60 points
Other Parts Discussed in Thread: TSB81BA3E

Hi,

Can you please help me with a problem I am having?

I have been battling to get S800 transmissions working with the 1394 PHY TSB81BA3E. We are interfacing to a custom link layer implemented in FPGA.

All other speeds work - S100, S200, S400, but not S800.

Upon further investigation, I noticed that a grant to the S800 bus request is received by the link layer, and the link layer "transmits" the data. However the data doesnt not appear on the bus - only prefix packets appear.

On receipt of the grant , the ctrl and d lines hold the value 11b (3h) and 00100111b (4Eh) respectively. 

What is interesting is that bit 7 of the d line is asserted (I dont know what this means, as it is not documented in the datasheet).

 

I may be a bit vague in my explanation, but please let me know if you require more information.

 

Thank you,

Harold

  • 0
    TI__Guru* 76130 points

    Hello Harold,

     

    Which protocol are you using on your LLC:

     1394a-2000 ?  or  1394b-2000?

     

    Regards.

  • 0 in reply to Elias Villegas M.
    Prodigy 60 points

    Hi Elias, 

     

    Thank you for your response. 

     

    I am using 1394b-2000 with the BMODE pin asserted.

     

    Thank you,

    Harold

  • 0 in reply to Harold Okai-Tettey
    TI__Guru* 76130 points

    Hi Harold,

     

    In the moment of the transmission crash, are you connecting the TSB81BA3E only to the LLC?  or are you using it as a repeater?

    Where I am trying to go with this question, is to know if some node is not capable of S800 speed, because if the node you are trying to communicate with is for example S200 only, no matter if your LLC and PHY are S800, you won't be able to transmit to that speed. (please see the image below as an example of the speed topology)

    Can you share your schematics and register dump of the PHY.

    Regards.

  • 0 in reply to Elias Villegas M.
    Prodigy 60 points

    Hi Elias,

    Thank you for that insight.

     

    It turned out that I had a non S800-compatible repeater on my network. I had in an OPTICIS S800 repeater (an electrical to optical repeater) on my device chain. I use this repeater to interface a FirespyB bus analyzer. So my device chain was as follows:

     

    DUT ------ (optical) ------ OPTICIS Repeater ------ (electrical) ------ FireSpyB Bus Analyzer

     

    where DUT is the device under test.

     

    My hardware collegue confirmed that there was a component in the OPTICIS S800 repeater that isnt S800 compatible. I removed this repeater and was able to get S800 working.

     

    Thank you for your help. Much appreciated.

     

    Harold