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Altera_Forum's avatar
Altera_Forum
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15 years ago

Pipeline Bridge

Hi,

i have a problem with the address calculation of the pipeline bridge.

I'am using Quartus 10.0 Sp1 and SOPC Builder.

To increase the system frequency, i want to use a pipeline bridge

tha is connected to a tristate bridge.

the tristate bridge is connected to three memories.

( See attachment )

Flash : 0x00000000 .. 0x03ffffff (64 MByte)

SRAM : 0x04000000 .. 0x040fffff ( 1 MByte )

FE-RAM : 0x04100000 .. 0x04101fff ( 8 KByte )

The "Base Address" from the Pipeline Bridge is 0x00000000 !

SOPC Calculates the "End Address" 0x07ffffff. Why ?

I expect that the "End Address" must have 0x04101fff.

Can anyone explain the address calculation of the pipeline bridge ?

Thanks,

3 Replies

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

    Because the address decode will always ignore low order bits - or, equiv, all items are 2^n bits wide.

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

    This is from chapter 11 of Quartus Handbook (Avalon Memory-Mapped Bridges):

    "The address span of an Avalon-MM bridge is the smallest power-of-two size that

    encompasses all of its slave’s ranges."
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    Thank you for your answers.

    Ok. Any Bridge, (Clock Crossing or Pipeline) delivers a new Master Port to the Components that are enclosed from the Bridge.

    If i want to Address (64 MByte + 1 MByte + 8KByte), the Master Port needs 27 Address lines to access all slave addresses.

    2^27 = 128 MByte = 0x07FFFFFF

    Result:

    The Address Range for my Pipeline Bridge is 0x00000000..0x07FFFFFF

    I have to think better soon ;-)