NIOS II C code tips?

Hi, look at "hello world" example, it is a good starting point.

is your pwm a hardware module ? or are you making a c software that behaves like a pwm ?

If your PWM is a hardware module, you have to interface it to Avalon bus in your SOPC by maybe a PIO (Parallel Input Output) (this is quite simple).

In my opinion, pwm in software is a bad idea (especially if you work with FPGA) : because of interruptions, CPU instructions, access.....

For SOPC, you need a PIO.

For software, You need an counter (simple) or a timer (a little difficult) and some comparators.

int i =0;
while(1)
{
  i++;
  if (i == periode)
  {
    IO_WRITE_...(0); // write '0' to your PIO
    i = 0;
  }
  elseif (i >= pwm)
  {
     IO_WRITE_...(1); // write '1' to your PIO
   }
//...
}

i know but it's for a small research project in a class of mine. I did a pwm model using quartus and VHDL code and i need to do one using SOPC Builder and NIOS to compare the timing analysis results between the two.

the system itself is very simple i have 8 input PIO to fix the duty cycle wanted and one output and while the c code itself is very easy i can't find any document that explain how to write a c project for NIOS from Zero or how to write the C code in NIOS (like using IOWR and IORD for example). we find one in Chinese so it wasn't very helpful although the illustration in it did make things a little clear...

You could look at literature on altera web site, there are "getting started" and tutorials.

With NIOS you get examples : "hello word" which lights up leds on altera nios dev kits with IOWR instructions. It is a good starting point, a good example you can modify.

There are NIOS documentations on IORD , IOWR ... macro functions.

Look at examples included in Quartus and Nios

10x alot this was very helpful here's my final code

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/*

PWM Code

*/

# include <stdio.h># include "system.h"# include"altera_avalon_pio_regs.h"

int alt_main()

{

int n; // PWM total period

int a; // PWM working period

int c=0; // internal counter

while(1)

{

n=IORD(PIO_0_BASE,0);// pio_0 (total period )

a=IORD(PIO_1_BASE,0);// pio_1 (on period)

if (n<a)

{

c=0;

IOWR(PIO_2_BASE,0,0);

}

if (n>=a)

{

c++;

if(c<a)

{

IOWR(PIO_2_BASE,0,1);

}

if(c>a && c<=n)

{

IOWR(PIO_2_BASE,0,0);

}

if(c>n)

{

c=0;

}

}

}

return 0;

}

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