a question for printf() function

hi everyone:

i made a nios project, use jtag-uart, the code is as follows:# include "alt_types.h"# include "altera_avalon_pio_regs.h"# include "sys/alt_irq.h"# include "system.h"# include <stdio.h># include <unistd.h>

void delay(void);

int main(void)

{

alt_u8 timer = 0;

while(1)

{

printf("Hello NIOS II! %d\n",timer);

IOWR_ALTERA_AVALON_PIO_DATA(PIO_BASE,timer); // connect to a led

delay();

timer++;

}

return 0;

}

//&#24310;&#26102;&#20989;

void delay(void)

{

alt_u32 i=0;

while(i < 4000000)

{

i++;

}

}

the function of the code is very simple: use jtag-uart output ""Hello NIOS II! timer" and make a led blink.

the project works correct when i first download the *.sof file and then download *.elf file. i see the jtag-uart receive data and the led blinking.

then i want to download the configure file to the EPCS Serial Configuration Device, so i add a EPCS Controller Core, and then download the configure file.

then problem comes:

i find the led only blink once.

if i comment the printf() function, the led starts blinking.

why?

is it because the jtag-uart is not on receive mode so the code stuck in the printf() function?

i think the jtag-uart printf() function is very useful during programming for debug, it can send out a lot information, such as whether a component works correct.

does it mean that i should comment all the jtag-uart printf() when i want to download the configure file to the EPCS Device??

thanks