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Altera_Forum's avatar
Altera_Forum
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16 years ago

No byte enable

Hi,

I am trying to create my own component using Avalon-MM. When I am generating sopc system I am getting following error:

Warning: 32-bit master connected to 128-bit slave with no byte enables (cpu/data_master -> mycomp_add/slave) at c:/altera/91/quartus//sopc_builder/bin/europa/europa_utils.pm line 248.

Can anyone suggest how to solve it?

Thanks,

Mumble.

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Looks like you'd like a different answer than the one you've already been given in another post.

    The NIOS data master is 32-bits wide and it isn't going to get any bigger. Now the avalon interconnect fabric will handle adaptation between the NIOS' 32-bit master and your 128-bit slave. However, the way it does this is it addresses a portion of your 128-bit bus with each access. If you don't provide byte enables, each time the NIOS performs a 32-bit write to your slave, 96 of the 128 bits will get written with bogus data.

    The solution is to add byteenables to your slave.

    Jake
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    Correct, thats the only solution.

    Only byteenable signals tell the slave which byte (bits) should be modified and which should keep their content.