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Altera_Forum's avatar
Altera_Forum
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21 years ago

How to deal with the additional address line?

I use IUL in SOPC to add a memory slave peripheral.I add 18 address line (add[17..0]) and then

in the Quartus it appears add[19..0], I read the datasheet of AvalonBus about Dynamic bus sizing.

But I did't understand it.Did I leave the add[0] and add[1] blank or something?

Thanks a lot.http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    which version of quartus and Nios are you using ?

    what are your settings of user logic in sopc builder (mainly databus width ?)?

    with dynamic bus sizing:

    8 Bit Databus : connect A0..Ax of RAM to A0..Ax of NIOS ADDRESS BUSS

    16 Bit Databus : connect A0..Ax of RAM to A1..A(x+1) of NIOS ADDRESS BUSS

    32 Bit Databus : connect A0..Ax of RAM to A2..A(x+2) of NIOS ADDRESS BUSS

    in case of 16 Bit Databus leave A0 of NIOS ADRESS BUS unconnected

    in case of 32 Bit Databus leave A0+A1 of NIOS ADRESS BUS unconnected

    REMARK:

    Altera told me that there was a change in the addressing scheme with NIOS 1.1 for

    native slaves.

    Table 15 Page 100 of Avalon Bus Specification should be corrected as

    following:

    Alignment | Master Width | Slave Width | A[0] of Slave is connected to Byte Address Bit Number

    native | 32 | 32 | A2(NIOS1.0) A2(NIOS1.1)

    native | 32 | 16 | A2(NIOS1.0) A1(NIOS1.1)

    native | 32 | 8 | A2(NIOS1.0) A0(NIOS1.1)

    dynamic | 32 | 32 | A2

    dynamic | 32 | 16 | A1

    dynamic | 32 | 8 | A0

    PLEASE correct me if i tell something wrong!
  • Altera_Forum's avatar
    Altera_Forum
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    21 years ago

    If your peripheral has a native data width between 17 and 32 bits then this sounds correct (would want to access 4 bytes at a time so A[0] and A[1] are not needed).

    Fischer the change you are referring to appears in SOPC Builder 4.2 and up. It was specific to native tri-state slaves (in short before 4.2 they did not behave the way you describbed and now they do).

    If you can describe your peripheral and the bus it is connected to we can give you a better answer.