Forum Discussion

gyuunyuu's avatar
gyuunyuu
Icon for Contributor rankContributor
5 years ago

What is the recommended methodology to create and use AHB/APB/AXI custom components inside Qsys?

In order to design and use APB/AHB/AXI custom components inside Qsys the following things must be clarified:

1. Does Qsys interconnect support these interfaces?

2. How does one interconnect components that have different interfaces on the two ends from APB/AHB/AXI/Avalon and make them work successfully?

3. How is the "address space" resolved in this case?

4. What are the disadvantages/drawbacks of creating a system that has mixture of components with these different buses? I assume that there would be certain clashes since they do not work in identical manner.

Very importantly:

5. Does Qsys contain BFMs to help verify APB/AHB/AXI custom "master" and "slave" components? I can see there are a lot of AXI BFMs but will have to figure out why we need so many.

And finally:

6. What are the official recommended guidelines for creating such a design in Qsys?

Any advice on this issue would be great. Intel FPGAs have superior debug tools than some other vendors. However, use of non-Intel FPGAs may be required to due project constraints. In this case, one can create and verify the design functionality inside Intel FPGA and then port it to the other device. This is why this question is important since Avalon is only supported inside Intel FPGAs. The design does not contain HPS.

4 Replies

  • sstrell's avatar
    sstrell
    Icon for Super Contributor rankSuper Contributor
    5 years ago

    First of, assuming you are familiar with Platform Designer (previously called Qsys), check out this online training:

    https://www.intel.com/content/www/us/en/programmable/support/training/course/oqsys3000.html

    Then, your questions:

    1) Yes, it does. See the Platform Designer user guide (not sure if you're using Standard or Pro so select the appropriate guide):

    https://www.intel.com/content/www/us/en/programmable/products/design-software/fpga-design/quartus-prime/user-guides.html

    2) You just make connections between masters and slaves, and sources and sinks. The tool does the rest. See the user guide for details.

    3) Can you clarify your address space question? The address space for a memory-mapped interface is based on the slaves attached to a particular master, which you set up in Platform Designer.

    4) The user guide discusses how different interfaces can work with each other. Platform Designer automatically generates translation components in the interconnect to allow interfaces to talk to each other. The disadvantage to this is the added logic to the design which, depending on the design and settings, could affect overall performance and potentially, though rarely, cause timing issues.

    5) There are many BFMs available just for this purpose. On the user guides list (https://www.intel.com/content/www/us/en/programmable/documentation/lit-ug.html) search for axi to see the guide for the BFMs.

    6) Platform Designer outputs plain HDL code (except for if you are using licensed IP, then it's encrypted) even for Avalon. As far as recommended guidelines, the user guide referenced above is your best source of info.

    Hope that helps.

    #iwork4intel

    • gyuunyuu's avatar
      gyuunyuu
      Icon for Contributor rankContributor
      5 years ago

      Thanks for this answer. I am trying to get access to the training course but is not working yet. I have sent an email to the FPGAtraining@intel.com to fix this.

      I assume that this "Mentor Verification IP Altera Edition AMBA AXI3 and AXI4" is the related to the BFMs found inside the Qsys. I have a few more questions based on this:

      1. Since this document states AMBA and then AXI3 and AXI4, why are the AMBA buses like APB and AHB missing from this document completely?

      2. The Aldec ActiveHDL simulator is missing from the list of supported simulators in the user guide. Who should be contacted to get to the bottom of this?

      Out of curiousity, I also intrigued by a few other things:

      1. Is Avalon able to provide all the functionality that exists inside AMBA and AXI buses or is it inferior in some way? I would assume so due the more limited application of AMBA.

      2. If AMBA or AXI components are used, are they converted into Avalon and then back by the Qsys interconnect?

      I shall continue study of the user guides.

  • KennyT_altera's avatar
    KennyT_altera
    Icon for Super Contributor rankSuper Contributor
    5 years ago

    I try to access the training without any problem. can you try different browser for it?

    1) May I know which document that you were referring to?

    2) May I know what is the missing list of supported simulators that you referring to?

    1) Nope, avalon will have a different spec compare to AMBA.

    https://www.intel.cn/content/dam/altera-www/global/zh_CN/pdfs/literature/hb/qts/qsys_optimize.pdf

    For more information about Avalon and AMBA interfaces, refer to the Avalon Interface Specifications and the AMBA Protocol Specifications on the ARM® website.

    If you able to launch https://www.intel.com/content/www/us/en/programmable/support/training/course/oqsys3000.html, it will show a lot of detail there as well.

    2) nope, there will be extra translator added in btw the connection. You can check it in show system with qsys interconnect.

    https://www.youtube.com/watch?v=LdD2B1x-5vo