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vr_ahb read data when response is ERROR

spark

Hi all,

I found the AHB eVC's read data has problem when the reponse is ERROR.

For testing a AHB master, I add an active AHB slave in eVC config file. For tracing the transfer I realize a simple scoreboard to recordthe transfer data like below. 

extend AHB SLAVE vr_ahb_agent_monitor {
    on tr_ended {
        if (cur_transfer.kind is not in [IDLE,BUSY]) {
            sys.scbd.record(cur_transfer);
        };
    };
};

I found when cur_transfer is READ and HRESP=ERROR, the HRDATA will become to zero but I checked the HDL waveform, the HRDATA is not zero, I dont know why eVC return the error read data when resp is ERROR. 

  • Hi,

    Response = ERROR means that the slave could not answer with data, i.e. the rdata value that you see on the bus is probably randomized.

    I would suggest you to collect transfers in the scoreboard only if the slave responded with a valid data, i.e. only when the response is OKAY.

     

  • Thank for your reply.

     

    Allthrough the rdata value may be randomized but I am strange that why the rdata collected by scoreboard is different with rdata in hardware. I think the rdata in hardware is also generated by eVC it should be same as data colected by scoreboar.

  • I understand what you are saying.

    It seems reasonable that the monitor should collect the data that appears on the bus.

    I will open a CCR for that.

    Thanks !

    BTW, you are not stuck with implementing the scoreboard, right ?

  • Thank for your reply.

    Misha Moroshko said:
    BTW, you are not stuck with implementing the scoreboard, right ?

    I can use the hardware signal directly but I think it is not good. Now I fix the reponse to OKAY to ignore this problem.

     

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