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Altera_Forum
Honored Contributor I
775 Views

Why is my software not producing the correct Avalon write?

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
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5 Replies
Altera_Forum
Honored Contributor I
20 Views

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
Honored Contributor I
20 Views

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
Honored Contributor I
20 Views

 

--- 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
Honored Contributor I
20 Views

 

--- 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
Honored Contributor I
20 Views

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?
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