Re: Why is my software not producing the correct Avalon write?

Altera_Forum · ‎06-09-2015

I have my nios connected to an Avalon memory mapped bridge that will allow me to communicate with an external RTL component. All I am trying to do is read and write to a register in the RTL component, but no matter what I do I can not get writes to assert. My Avalon bridge is located at address 0x002_0000 - 0x002_0FFF. My code to write to the Avalon master is as follows:

.text
.global main
.type main, @function
main:
  movi r10, 0x0020000
  movi r9, 0x00AA
  stwio r9, (r10)
end:
    br    end
.end

Altera_Forum · ‎06-09-2015

Hi,

Are you sure the address is correct ? The bridge changes the address, you need to add the bridge's address with the Avalon-MM slave component, to get the final address.

Did you use signal tap to see if the bus transaction is correct ?

Altera_Forum · ‎06-09-2015

Be careful with Avalon bridges. Check that you address is in DWords and not in symbols. Your address 0x20000 might be actually translated to 0x8000.

Thanks,

Evgeni

Altera_Forum · ‎06-09-2015

--- Quote Start ---

Hi,

Are you sure the address is correct ? The bridge changes the address, you need to add the bridge's address with the Avalon-MM slave component, to get the final address.

Did you use signal tap to see if the bus transaction is correct ?

--- Quote End ---

I am currently running signal tap now and I am not seeing the write transaction I requested.

What exactly do you mean that the bridge changes the address? I am looking at the address map in qsys and I see that the bridge is located at 0x0002_0000.

Altera_Forum · ‎06-09-2015

--- Quote Start ---

Be careful with Avalon bridges. Check that you address is in DWords and not in symbols. Your address 0x20000 might be actually translated to 0x8000.

Thanks,

Evgeni

--- Quote End ---

I did make sure to set the address to words.

Altera_Forum · ‎10-02-2015

Did you connect your custom component within Qsys or the bridge is exported? Are you using Avalon-MM pipeline bridge?

I hope that you did not export the bridge directly.

Can you share you Qsys system design/address map?