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Honored Contributor
Honored ContributorWhy my Nios II run slowly ?
Dear all, I have do experiment on the Cyclone V SOC. [Helio evaluation board] And I put one nios/e and onchip-ram into the FPGA fabric. Currently, I could read/write the data in...
Altera_ForumHonored Contributor
Honored ContributorCount the instructions in the loop:
1) Read of LED_TOGGLE for the io_write 2) Write of LED_TOGGLE to the hardware 3) Read of LED_TOGGLE for the invert 4) the invert inself 5) Write back of LED_TOGGLE 6) Unconditional branch IIRC a nios/e takes 5 clocks per instruction - so that is at least 30 clocks. The constant LED_PIO_DATA_BASE might also be created each loop iteration. Add in any extra clocks for the avalon write caused by your slave itself. Make LED_TOGGLE a local variable (so it can be assigned to a register). Compile with -O2 so that the compiler moves some calculations outside the loop. That should get you to a three instruction loop.
