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Coverage item of AHB eVC

spark

Hi all,

In AHB eVC there is transition__transfer_kind defined in tr_ended_master_cover and tr_ended_slave_cover. I am strange that how to generate IDLE=>BUSY and IDLE=>SEQ, I think IDLE is not allowed during an AHB burst, only BUSY can be inserted.

Next item is BURSTS_VS_TERMINATIONS_VS_KINDS in burst_ended_master_cover. Look this following case,

burst_kind/locked/termination/last_transfer_kind=INCR4/FALSE/OKAY/BUSY,

because the master termination is OKAY no ERROR is occured then the burst will not be early terminated, I think the last_transfer_kind will be SEQ in INCR4. Does my understanding of AHB protocol have some problem?

 

  •  Hi,

    Bellow is RnD response:

    The user points on two argument, I will try to answer on these two argument

    1.       The user is right we can’t have IDLE in middle of burst and this is why we use coverage Ignore on these two transition (IDLE=>BUSY and IDLE=>SEQ).

    2.       I think this is the relevant part in  AHB spec (master can insert BUSY transfers in middle of burst):

    “The BUSY transfer type allows bus masters to insert IDLE cycles in the middle of bursts

    of transfers. This transfer type indicates that the bus master is continuing with a burst of

    transfers, but the next transfer cannot take place immediately. When a master uses the

    BUSY transfer type the address and control signals must reflect the next transfer in the

    burst.

    The transfer should be ignored by the slave. Slaves must always provide a zero wait state

    OKAY response, in the same way that they respond to IDLE transfers.”

    so I think there is no problem with this  case (burst_kind/locked/termination/last_transfer_kind=INCR4/FALSE/OKAY/BUSY).

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