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AM335x PRU ICSS questions

Guru 10570 points
Other Parts Discussed in Thread: TLK110

Hello.
I have basic questions about PRU-ICSS.
I would like to use PRU-ICSS as Profinet or EthernetIP.

a) Which emac mode can PRU-ICSS support, RMII, MII or both?

b) Does PRU-ICSS need all of RMII/MII signals to connect PHY for proper operation ?

c) There are some multiplexed pins on PRU-ICSS (ZCZ package).
I can choose which pin to use. Is that right?



d) When AM335x operate as OPP50, PRU-ICSS also operate as Max 100MHz.
Are there any other restriction?
e.g. some peripheral does not operate as OPP50. etc..

Best regards, RY

  • Hi RY,

    Currently the PRU_ICSS is not supported by TI. This may soon change, but I cannot say how or when. For the moment information about this subsystem can be found here: https://github.com/beagleboard/am335x_pru_package

  • Hi,

    Please find the replies to your questions below:

    a). PRU-ICSS supports MII interface only.

    b). Apart from "TXER (Transmit Error)" signal, you need to connect all other MII signals including COL (Collision detect)  and CRS (Carrier sense) since you mentioned EthernetI/P which supports half duplex.

    c). I will direct this question to right people and we will get back with answer.

    d). For PROFINET and EthernetI/P to work on AM335x, you would need to operate it at OPP100.

    Regards,

    Robin

  • Biser-san,

    Thank you for your reply.
    I understand about PRU_ICSS low level support from TI.
    But, my question is case using ISDK based on protocol FW provided from TI.

    Could you check my question?

    Best regards, RY

  • Robin-san,

    Thank you so much for your support.
    It is very helpful for me. And I am waiting about c).

    Best regards, RY

  • Hi RY,

    Please find the reply to your question c) below:

    c) Only a limited set of pin combinations (or IO Sets) are allowed. The IO Sets are used to guide the user into using a tested configuration that meets timing requirements. The AM335x Pin Mux Utility can be used to help select a valid IO Set. Additional details about IO Sets are included in the Pin Mux Utility wiki page here.

    Regards,
    Melissa


  • Melissa-san,
    May I have once more confirmation?
    I am evaluating Profinet and Ethernet/IP.

    In ICSv2, The connection is following:
    It seems ICEv2 is NOT supported 10Mbps operation.
    Because, when it operates as 10Mbps, TLK110 LED_SPEED pin will assert low to PR1_MIIx_RXLINK in AM335x.
    It means RXLINK is not detected.

    Is my understanding right?

    Best regards, RY

    ICEv2.1 connection:

    TLK110 datasheet: 

  • RY,

    the schematic of the board is one thing. But it is still a question if the (PRU) software evaluates the RXLINK signal. I assume this would be protocol dependent. For example for Profinet 10Mbps is not an available option. I don't think we are using RXLINK in our Profinet device implementations.

    Actually for Ethernet/IP we need to support 10Mbps but I am not the expert here.

    Regards,

  • Frank-san,

    Thank you so much!!
    Your answer is very helpful. I could understand.

    Best regards, RY