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Valued Contributor III

Nios II/s Doesn't Work w/ JTAG?

Hey everyone, 

I'm having some trouble here. I have made a system using SOPC builder, containing
  • 1 NiosII CPU 

  • 1 tri-state Avalon bridge 

  • 1 CFI flash memory module 

  • 1 DDR SDRAM module 

  • JTAG/UART module 

  • A mutex 

  • sysid
and it's running the simple 'Hello World!" program. 


This is a test system to try before moving on to a multi-processor system, which si why you see the mutex, sysid etc.. 


I am doing simulation only, using modelsim-ase. 


The problem I am having is that using the Nios II/e and Nios II/f simulates the program fine. 

but when I use a Nios II/s, the JTAG simply does not work. It does not output anything. The only thing that happens with JTAG when using the II/s is it writes a 0x1. The Nios2 appears to be stuck reading and writing to data memory (SDRAM). I am unsure exactly what it's doing or writing, so any sort of literature that would help clear that up would help. 


I am unsure of the problem. I can reproduce this easily by simply changing the Nios II to /s from /e or /f, regenerating, recompiling in Nios EDS and resimulating. 

I have not seen any errors or warnings in SOPC builder, Nios2 EDS or modelsim. 


Am I missing something here? What is different about the /s? Isn't it supposed to be a mix between the /e and /f in terms of area and speed?
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