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AMBA AHB TRANSFER CONTINUE AFTER ERROR RESPONSE

Vishal

Hello everyone,


Please describe me the transfer continuation process after ERROR response from the slave.ERROR response.jpg

As shown in the above figure at cycle T4 if MASTER identifies the ERROR response from the SLAVE. Now, if the MASTER wants to continue the current transfer then how can it?

Does it need to insert SEQUENTIAL transfer for the continuation of the current transfer or it has to insert IDLE transfer then NONSEQUENTIAL transfer to complete the current transfer?

Regards,

Vishal

Parents
  • 0 in reply to Vishal

    Hello Vishal,

    you are right, I'm very sorry,

    As you say, the MASTER should drive address 0x2C at T4 and HTRANS=SEQ in order to continue the current transder.

    If the SLAVE could not accept address 0x2C, the HREADY would be low and  HRESP would be ERROR at T5,  and HREADY would be high and HRESP would keep ERROR at T6.

    Best regards,

    Yasuhiko Koumoto.

Reply
  • 0 in reply to Vishal

    Hello Vishal,

    you are right, I'm very sorry,

    As you say, the MASTER should drive address 0x2C at T4 and HTRANS=SEQ in order to continue the current transder.

    If the SLAVE could not accept address 0x2C, the HREADY would be low and  HRESP would be ERROR at T5,  and HREADY would be high and HRESP would keep ERROR at T6.

    Best regards,

    Yasuhiko Koumoto.

Children
  • 0 in reply to Yasuhiko Koumoto

    So finally can the summary be:

    " If the SLAVE gives ERROR response (due to any reason for example wrong address) for any transfer; the MASTER can change address information during the second cycle of ERROR response (though the HREADY signal is low) with SEQ transfer to continue the current transfer."

    Thanks,

    Vishal

  • +1 in reply to Vishal

    Hello Vishal,

    I could not found the statement in the "AMBA® 3 AHB-Lite Protocol Specification v1.0 (ARM IHI 0033A)".

    From where do you bring it?

    Is it your own statement?

    Anyway, I fully agree with you.

    For your information, in addition to your statement, I would show the following statements from "AMBA® 3 AHB-Lite Protocol Specification v1.0 (ARM IHI 0033A)".

    3.5.2 Early burst termination

    Slave error response
    If a slave provides an ERROR response then the master can cancel the remaining transfers in the burst. However, this is not a strict requirement and it is also acceptable for the master to continue the remaining transfers in the burst.
    If the master does not complete that burst then there is no requirement for it to rebuild the burst when it next accesses that slave. For example, if a master only completes three beats of an eight-beat burst then it does not have to complete the remaining five transferswhen it next accesses that slave.

    5.1.3 ERROR response

    If a slave provides an ERROR response then the master can cancel the remaining transfers in the burst. However, this is not a strict requirement and it is also acceptable for the master to continue the remaining transfers in the burst.

    The ERROR response only indicates a convenience of the SLAVE side. The MASTER can sometimes continue the transferring (while caring about HREADY). The ERROR response is only a sign that the MASTER can cancel the current transaction.

    Best regards,

    Yasuhiko Koumoto.

  • 0 in reply to Yasuhiko Koumoto

    Thanks Yasuhiko,

    The conclusion regarding  "the MASTER changing the address during the second cycle of ERROR response to continue the current transfer" ; I thought it from the specification sheet named  "AMBA® 3 AHB-Lite Protocol Specification (ARM IHI 0033A)" (Page No 3-10). Here I have mentioned it :

    Slave error response
    If a slave provides an ERROR response then the master can cancel the remaining transfers in the burst. However, this is not a strict requirement and it is also acceptable for the master to continue the remaining transfers in the burst.

    You can see the bold statement : "However, this is not a strict requirement and it is also acceptable for the master to continue the remaining transfers in the burst."

    But in the specification it is not explained through detailed diagram ; hence I thought regarding the continuation of the burst and posted it on the forum to check whether it is appropriate or not.

    Of course I got the correct understanding and endorsement from your side ; thanks for that.

    Regards,

    Vishal