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andy25's avatar
andy25
Icon for Occasional Contributor rankOccasional Contributor
2 years ago

Nios V exception code

I have a Nios V and an "Avalon FIFO Memory Intel FPGA IP" fifo I'm trying to read in C.

I can read the status and length just fine:

// works
int len = altera_avalon_fifo_read_level(IPMB_FIFO_IN_CSR_BASE);
// works
if(!altera_avalon_fifo_read_status(IPMB_FIFO_IN_CSR_BASE, ALTERA_AVALON_FIFO_STATUS_E_MSK))
{
   // dies
   int sample = IORD_ALTERA_AVALON_FIFO_DATA(IPMB_FIFO_OUT_BASE);

in gdb, I can see IORD causes an exception_code 4:

Program received signal SIGTRAP, Trace/breakpoint trap.
handle_trap (cause=4, epc=1512, tval=134414729) at HAL/src/alt_irq_handler.c:106
106	            NIOSV_EBREAK();
(gdb) p exception_code 
$4 = 4
(gdb) p is_irq
$5 = 0

Whats an exception code 4? Is there a list someplace?

Is *_FIFO_OUT_BASE the right thing to pass to IORD_ALTERA_AVALON_FIFO_DATA?

Thanks for your time,

-Andy

Nios Cpu

6 Replies

  • andy25's avatar
    andy25
    Icon for Occasional Contributor rankOccasional Contributor
    2 years ago

    The problem was caused by Platform Designer's System -> Assign Base Address to assign the FIFO's out base address to an odd number.

    When I change the base address (IPMB_FIFO_OUT_BASE) to an even number it no longer crashes.

    I'm still curious where I can find a list of exception codes, or find info about what a 4 means.

    -Andy

  • EBERLAZARE_I_Intel's avatar
    EBERLAZARE_I_Intel
    Icon for Regular Contributor rankRegular Contributor
    2 years ago

    Hi,


    Thanks for the feedback on the Platform Designer, I will channel this to our internal team.


    Regarding the exceptions code 4, I will check on my side and get back to you.


  • EBERLAZARE_I_Intel's avatar
    EBERLAZARE_I_Intel
    Icon for Regular Contributor rankRegular Contributor
    2 years ago

    Hi,


    I am still trying to get the info on the exception code, I shall get back to you.


    • andy25's avatar
      andy25
      Icon for Occasional Contributor rankOccasional Contributor
      2 years ago

      Nope. Everything runs fine as long as I have an even base address.

      After running the Auto Assign Base Address thing, I just have to remember to check them.

      -Andy

  • EBERLAZARE_I_Intel's avatar
    EBERLAZARE_I_Intel
    Icon for Regular Contributor rankRegular Contributor
    2 years ago

    Hi,


    I now transition this thread to community support. If you have a new question, Please login to ‘https://supporttickets.intel.com’, view details of the desire request, and post a feed/response within the next 15 days to allow me to continue to support you. After 15 days, this thread will be transitioned to community support. The community users will be able to help you on your follow-up questions.



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