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Documentation for the OpenHW Group's set of CORE-V RISC-V cores
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need clarification of obi protocol's be and addr signals' combination #578

Closed spzeno closed 1 year ago

spzeno commented 1 year ago

need clarification of obi protocol's be and addr signals' combination

Background information

I am writing a obi to axi adapter.

According to obi v1.5 spec, to access one byte at 0x00006001, both below two be and addr signals' combinations are legal:

  1. be==4'b0010 and addr=32'h0x00006000
  2. be==4'b0010 and addr=32'h0x00006001

(or do I have any misunderstanding?)

However, as I look for PULP's [per2axi](https://github.com/pulp-platform/per2axi) module and [core2axi](https://github.com/pulp-platform/core2axi) module, it seems like they use obi's addr as axi's addr directly. Thus I think there may need some clarifications.

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Document Location

https://github.com/openhwgroup/programs/tree/master/TGs/cores-task-group/obi

MikeOpenHWGroup commented 1 year ago

Hello @spzeno thanks for the question. To the best of my knowledge, the PULP team has not adopted the OBI protocol. This protocol is supported by the OpenHW CV32E40P, CV32E40S and CV32E40X cores and soon the CVE2 will be updated to adopt OBI. There is no expectation that the PULP team will use it and OpenHW certainly does not expect PULP to use OBI (even though we think it is a great spec! :wink:).

We are happy to address any OBI questions you may have, but we cannot comment on non-OpenHW use of OBI.

spzeno commented 1 year ago

I understand. Thanks for your reply.