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Why is my software not producing the correct Avalon write?

Altera_Forum
Honored Contributor II
833 Views

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 II
78 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 II
78 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 II
78 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 II
78 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 II
78 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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