C Program only runs on NIOS 2 IF a printf is in the code.

Altera_Forum · ‎04-16-2013

Hi, i am using quartus version 11.1 and i am using the tool for eclipse to make my c programs so that i can run them on the nios 2 hardware. I am using a altera de2 board.

I am working on a bigger project with VGA and keyboard and now I have made a "handshake communication" between the nios and a ram-controller. This is just so that i am not loosing any new input to the ram.

But this works very slowly, and with signal tap i have found out that it is nios that are extremly slow on reading the PIO as i use as a flag to tell when its okey to send next character.

I think the problem is for me in ecplise somewhere, for some reason i can not run ANY program that does not include a printf. It is like the compiler is optimizing away the code. Let me show you some examples that in my opinion should work but does not, not even on other nios system that i have created just to try, some small simple ones.

Checklist:

I have tried created new quartus projekt and new sopc files with new nios.

I have tried a new workspace in eclipse.

I have tried not changed anythings in the makefile.

For 4 weeks ago, it worked without the printf (I dont think that i have changed anything in eclipse, in that case, by mistake)

Ps: even programs without loops do only run with printf.

So, how should i do to be able to run c programs on my NIOS 2 that does not include a printf?

This will NOT work, using on_chip_memory

# define swit 0x01021010# define LEDR_BASE_ADDRESS 0x01021030
int main(void)
    {
(with or witout volatile, niether works) int * led = (int *) LEDR_BASE_ADDRESS;    
volatile int * switches = (int *) swit;
while(1)
{
*(led) = *(switches);
}
return 0;
}

But this WORKS, using on_chip_memory:

# define swit 0x01021010# define LEDR_BASE_ADDRESS 0x01021030
int main(void)
    {
(with or witout volatile, niether works) int * led = (int *) LEDR_BASE_ADDRESS;    
volatile int * switches = (int *) swit;
while(1)
{
*(led) = *(switches);
printf("Hello");
}
return 0;
}

this will NOT work, using sdram_memory:

# define lol 0x01021000# define ADDR_BASE_ADDRESS 0x01021040# define VGA_BASE_ADDRESS 0x01021030# define FLAG_BASE_ADDRESS 0x01021050
    int main(void)
    {
        volatile int * flag = (int *) FLAG_BASE_ADDRESS;
        volatile int * vga = (int *) VGA_BASE_ADDRESS;
        volatile int * addr = (int *) ADDR_BASE_ADDRESS;
        int state = 0;
        *(vga) = 'a';
        *(addr) = 0;
        while(1)
        {
        if((*(flag) & 0x01) == 0)
        {
            if(state == 0)
            {
            *(vga) = *(vga) +1;
            *(vga)= (*(vga) | 0x100);
            state = 1;
            }
            }
        else
        {
            if(state == 1){
            *(vga)= (*(vga) & 0x0FF);
            *(addr) = *(addr)+1;
            state = 0;
            }
        }
        }
    return 0;
    }

this WILL work, using sdram_memory:

# define lol 0x01021000# define ADDR_BASE_ADDRESS 0x01021040# define VGA_BASE_ADDRESS 0x01021030# define FLAG_BASE_ADDRESS 0x01021050
    int main(void)
    {
        volatile int * flag = (int *) FLAG_BASE_ADDRESS;
        volatile int * vga = (int *) VGA_BASE_ADDRESS;
        volatile int * addr = (int *) ADDR_BASE_ADDRESS;
        int state = 0;
        *(vga) = 'a';
        *(addr) = 0;
        while(1)
        {
printf("hi");
        if((*(flag) & 0x01) == 0)
        {
            if(state == 0)
            {
            *(vga) = *(vga) +1;
            *(vga)= (*(vga) | 0x100);
            state = 1;
            }
            }
        else
        {
            if(state == 1){
            *(vga)= (*(vga) & 0x0FF);
            *(addr) = *(addr)+1;
            state = 0;
            }
        }
        }
    return 0;
    }

SOLUTION:

The problem seems to only occure when in SOPC-builder choosing Processor -> Nios_processor -> and take the II/f core.

So if you get this problem just go for the II/e core and that way it worked fine for me.