Honored Contributorhey everybody
I'm trying to make a PWM using NIOSII and SOPC and i have reached the point where i need to wright the C code for my model but i can't find any documentation describing how to do it your self without downloading an external code ... any help? ps: i need to understand the structure of the c code needed and how to create the C project from zero .
Honored ContributorHi, 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).Honored Contributorit's a software module ...i'm trying to make a c software that behaves like a pwm.
Honored ContributorIn 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...Honored ContributorYou 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 NiosHonored Contributor10x alot this was very helpful here's my final code
--- Quote Start --- /* 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; } --- Quote End ---
