Frequently Asked Questions

Q. Why the ‘DE1-SoC Board’ is not recognized by Quartus?

Ans. USB blaster is not recognized. If you are using windows 8.1, follow the below steps:

1.Plug the USB-Blaster download cable into the PC. The following will appear on the screen: Device driver software was not successfully install. Select Click here for details.
2. Select Change settings…
3. Now cancel this (probably by selecting Cancel)
4. Open the Device Manager (Windows Key | Control Panel | Device Manage)
5. Under Other devices, USB Blaster should be listed. Right mouse click on this and then select Update Driver Software…
6. Select Browse my computer for driver software
7. Find c:\altera\91sp2\quartus\drivers\, then select Next; (Note: Stop at this folder, i.e., do NOT go deeper by opening a folder within the drivers folder)
8. Check the Always trust … box and then select Install


Q. What is the name of the FPGA that we are working with?

Ans. 5CSEMA5F31C6


Q. Why am I seeing the “memory address unassigned” error?

Ans. Reset vector and exception vectors need to be assigned. Go to Qsys->System->Assign Base Address.


Q. Why am I seeing “Verify fail” and “Processor Paused” errors from NIOS IDE while running programs?

Ans. Most likely causes are error in pin assignments, typos and reset button is On. Double check these issues.


Q. Why am I seeing the following message when downloading your program to the Nios II (when using SDRAM for the program)?

Using cable "USB-Blaster [USB-0]", device 1, instance 0x00

Pausing target processor: not responding.

Resetting and trying again: FAILED

Leaving target processor paused>


Ans. Possible reasons are following:

a.    Incorrect pin assignment in Quartus Prime (carefully check typos, and datasheet).

b.    There is an incorrect or missing PLL file for SDRAM delay.

c.    There is a misspelled control line in the Nios module interface, usually the clock or reset signal.

d.    The reset line is being held low/high by incorrect logic. 

Q. The compilation report generated after the compilation of the design shows a different board and subsequently the programming is unsuccessful. What is wrong?
Ans. This happens if for some reason you chose to remove pin assignments and then reassigned them again. Go to ‘Device’ menu and reselect the appropriate board.

            Q. Why am I seeing make file errors when I import a project and build it?

            Ans. Every time you import a project, make sure to run the ‘Generate BSP’ option by right clicking on the BSP project.


            Q. Why does Nios II take longer than expected when executing the usleep() C function?

Ans. The specification of the usleep function is to cause a delay at least equal to the value specified. The actual time that is taken to return from the function can be longer than this, but should never be shorter. It can also depend on the board type and its frequency. Hence, it is suggested to find the correct argument to be passed to usleep function to get the proper delay.


Q. The NIOS II IDE sometimes shows that the target connection to the board is lost. Why?

Ans. Sometimes when a project is imported in NIOS II IDE, it loses connection with the board. Use refresh connections option to reconnect the board to the NIOS II IDE.