Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
20 years ago

2 masters accessing a Slave

Hi ,

I am a nios newbie. We have a slave that has 16 byte address space,

Since we do word access, we have used 2 address lines for slave.

Nios and another master(created by us) access the slave. Does our

master need to have more than 2 address lines?

Our peripheral is automatically assigned address space 0x00 to 0x0F by

SOPC builder and we get a message saying it clashes with address space of flash.

Since we have locked the flash address space to start from 0x00, we

can't understand why our slave is assigned the same address range ?

does our master have to supply a 32 bit address ?

Kindly help...

regards

karthik

2 Replies

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

    Hi karthik,

    > Since we do word access, we have used 2 address lines for slave.

    Ok ... it's a 32-bit slave.

    > Does our master need to have more than 2 address lines?

    Yes, you&#39;ll need at least 4 for a 16-byte slave. From the Avalon Interface Specification:<div class='quotetop'>QUOTE </div>

    --- Quote Start ---

    Master addresses represent byte addresses, regardless of the data-width of the master port.[/b]

    --- Quote End ---

    > we get a message saying it clashes with address space of flash

    Change the address to an unused memory region.

    > Since we have locked the flash address space to start from 0x00, we

    > can&#39;t understand why our slave is assigned the same address range ?

    I just upgraded to 5.1 so I can&#39;t comment on this. I don&#39;t recall any problems

    in earlier versions. You can change the address in the mean time.

    Regards,

    --Scott
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    <div class='quotetop'>QUOTE </div>

    --- Quote Start ---

    does our master have to supply a 32 bit address ?[/b]

    --- Quote End ---

    I don&#39;t think so, Nios has the functionalities of both Native Address Alignment and Dynamic Address Alignment, you can get the detail informaiton in datasheet Avalon Interface Specification.

    David