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JLiew's avatar
JLiew
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6 years ago

Why is my nios custom instruction executing twice?

I have a NIOS2 custom instruction written in VHDL to communicate with my self-made FPGA components. It takes dataa and datab from the custom instruction and turns it into a communication bus of sorts...
Ahmed_H_Intel1's avatar
Ahmed_H_Intel1
Icon for Frequent Contributor rankFrequent Contributor
6 years ago

Hi,

I see the VHDL code is totally correct. But I am wondering how you are using this C-code function: Can you please send to me more details about this function?

unsigned com_bus_simple(unsigned dataa, unsigned datab)

{

unsigned readdata;

readdata = (unsigned)ALT_CI_NIOS_FPGA_COM_0(dataa, datab);

return readdata;

}

Plus, Can you please share more details about the connection to/from NIOS II?

Regards,

  • JLiew's avatar
    JLiew
    Icon for New Contributor rankNew Contributor
    6 years ago

    Hello,

    To be honest, I have since rewritten a completely new custom instruction (now an extended one) with the express purpose to not do a double send, and now it is working.

    I'll append both the old and new VHDL files and old and new examples of drivers that use it. Because, while I have a working instruction now, I still have no clue why the old one didn't work.

    I've put them in a zip, because, apparently I can only add one file per post?

    What would you want to know about the connection to and from the NIOS II? You mean how it is implemented in a FPGA entity?

    Thank you