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Altera_Forum's avatar
Altera_Forum
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21 years ago

Nios2 SDRAM+LAN bus sharing

Hi all!

I have been attempting to use the bus-sharing feature of the SDRAM controller, along with the LAN controller.

The SDRAM seems to be working okay!, but so far no luck with the LAN controller....

Can I ask some of you folks to verify that I have carried out the address bus part-select correctly on my schematic?

http://tinyurl.com/6goor (http://tinyurl.com/6goor)

It took me a while to work out how exactly to do this, but I'm assuming that I do not need the full A15..0 because the device driver does not use it all?

Have I broken anything by not supported the full A15..0 address bus?

Thanks!

;O)

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    21 years ago

    Hi,

    Does anybody have any experience with bus-sharing feature of the SDRAM controller?

    Thanks!
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    21 years ago

    I've never found a complete write up about the rules for signal names.

    I would recomment that you break the verticle bus that connects

    ext_ram_bus_address[15..0] and ext_ram_bus_address[11..0]

    That connection looks 'wrong' to me.

    Keep us posted
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    21 years ago

    I agree with gmm... I would expect Quiartus to give a compilation error becaue of a mis-matched bus width; you are attempting to throw away 4 address lines but Quartus doesn't know that.

    You should try this in case you're seeing such a compilation error: 

    addr ( from SOPCB ) ---- name the bus "my_addr"----x

    the 'x' means that you don't connect the line to anything. then, to get to your pin, make a separate named bus wire like this: 

       x----name this one "my_addr"--------<<--IO named "my_addr-->>

    Then quartus knows explicity that you want to connect 11..0 on your IO to 11..0 on the bus coming from the SOPCB module.