Intel® FPGA University Program
University Program Material, Education Boards, and Laboratory Exercises
1180 Discussions

NIOS II Custom Instruction CRC

Honored Contributor II



My lab partner and I are trying to get the custom instruction set to compile, but we run into two issues. 


1. We try to create the CRC components, but get duplicate signal type errors 


2. When we try to build the app from the NIOS II Shell, we get make errors stating that the ALT_CI_CRC_N has not been defined. 


My guess is that the first problem, could be causing the second. So how does one go about creating the custom instruction components? 



We are using the following files: 

Nios II Custom Instruction User Guide (ver 1.5, Jun 2008, 701 KB)  

Design Files for Nios II Custom Instruction User Guide (19 KB) 


Thank you in advance
0 Kudos
1 Reply
Honored Contributor II

What is the error message you are seeing? If the custom instruction isn't being correctly connected to the CPU then ALT_CI_CRC_N will not be defined in system.h 


I just looked at the document, I recommend creating the custom instruction using the component editor directly instead of attempting to open it from with the Nios II wizard. Just create a custom instruction slave interface and assign all the signals in the file "CRC_component.v" to the custom instruction slave. The file CRC_component is the top level file.
0 Kudos