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NIOS II stuck in reset

Honored Contributor II

Hello everyone, I'm having a problem which I feel may be down to a stupid mistake on my part, but I just can't find it so here I am. 


I've just received a DE1-SoC board and I wanted to design the simplest, smallest NIOS system I could (using only on-chip memory for code and data, and a single PIO for I/O). I've used a DE1 board a couple of years ago and I knew how to do that back with Quartus 9.1 so I dug out my old notes and did exactly what I used to do, but with Qsys instead of SoPC Builder : 


- I created a system with a NIOS II/e core, on-chip ROM for code, on-chip RAM for data, one PIO 

- I made all the connections that needed to be made and exported the PIO I/O 

- I generated the system, instanced it the block diagram for my project's top-level entity, assigned the pins, etc... 

- I ended up with a *.sof file 

- I wrote a few lines of C code in a file (a main function that writes to the PIO) 

- I launched the Altera Monitor, created a new project, pointed it to my Qsys file, SOF file and C source file 

- I used the monitor to configure the board, compile and load the code 


Up to that point, everything went like a charm, the few LED I had programmed as status indicators came up, and I was ready to start executing my code. So I hit the "play" button in the monitor... 


And nothing happened. 


I hit the pause button and found out I was still at address zero (my reset vector). If I hit the step button, I still remain at address zero. If I double click anywhere in the disassembly window and hit the step button, I immediately go back to address zero. 


Basically, my system is showing all the symptoms of a stuck reset. 


I went back to Qsys, thinking I had probably misconnected the reset signal, and even tried several variations on the theme of bringing a reset signal to the NIOS core, but to no avail : I can't get my NIOS core to execute a single instruction. 


Do you have any idea what I might have done wrong ? I've went through every dialog box I could find and saw no option that would help me, and the tutorials haven't proved helpful either. 


As princess Leia would say, you're my only hope, guys. 


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