Easy nios design with buttons

[Altera_Forum]

Hello, 

 I am a newbie with Quartus II and Nios II and I have been trying to do an easy nios design in order to light on a led when pressing a button. I am working on the Altera Cyclone III EP3C25F324 board. I think the problem comes from my code in nios II that I put below. I don't really know when to write "IOWR_ALTERA_AVALON_PIO_DATA(...);" maybe the problem comes from here. Plus, when I try to write some "printf", there is an error :   collect2: ld returned 1 exit status make: *** [button_led.elf] Error 1   Here is my program :   #include "system.h"# include "altera_avalon_pio_regs.h"# include "alt_types.h"# include "stdio.h"# include "stdlib.h"  int alt_main (void) {  alt_u8 led = 0x2;  alt_u8 button = 0x2;    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, led);  IOWR_ALTERA_AVALON_PIO_DATA(BUTTON_PIO_BASE, button);    while (1)  {  switch (button) {  case 0x1 :  led=0x1;   break;  case 0x2 :  led=0x2;   break;  case 0x4 :  led=0x4;   break;   case 0x8 :  led=0x8;   break;  }  }  Do someone can help me? Thank you very much,  Myriam

[Altera_Forum]

try this: 

# include "system.h"# include "altera_avalon_pio_regs.h"# include "alt_types.h"# include "stdio.h"# include "stdlib.h"  int alt_main (void){  alt_u8 button = 0x2;   while(1){  button = IORD_ALTERA_AVALON_PIO_DATA(BUTTON_PIO_BASE); IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, button); }  }

[Altera_Forum]

It lights on the 4 leds without any change when I press a button.  

Maybe it comes from my quartus II design ?

[Altera_Forum]

I would double check the pin connections of the buttons . A good tip is to use signal tap to see if anything happens on those pins.  

 //Bango

[Altera_Forum]

I am trying your idea but it is the first time I am unsing the tap signal interface and I am not succeeding. I read the literature on Altera but I still don't understand my mistakes. First, a word about my design. I added to the CIII_NiosII_Small design provided by Altera a BUTTON[3..0] signal as another entry. On the SignalTap II Embedded Logic Analyzer, I added the four signal (corresponding to each button), the clock and entered the hardware setup (USB). 

 Now I have errors from the Analyzer :  ISED_PROGRAM_DEVICE CAUSE: You attempted to run the SignalTap II Logic Analyzer, but the current design does not match the design programmed in the device. ACTION: Program the device with the current design, and re-attempt to run the run the SignalTap II Logic Analyzer.  And from Quartus :  Error: Current license file does not support incremental compilation  Can you help me ?

[Altera_Forum]

1. Check your pin assignments. 

2. Verify that your base addresses for PIOS in SOPC are same that ones in "system.h".

[Altera_Forum]

Hello, 

 I've been doing some other stuff and I am now back to my button design. I checked my pin assignments (they are fine) and my base addresses for PIOS in SOPC and the ones in "system.h" matches. I tried the easy program below and when I press the button, nothing happens. It seems that there is still another connection problem but I don't know which one.  int alt_main (void) { alt_u8 button = 0x2;  while(1){ button = IORD_ALTERA_AVALON_PIO_DATA(PIO_0_BASE); if (button==0x01) printf("button 1"); }  return 0; }  Thanks for your patience,  Myriam

[Altera_Forum]

Hello, 

 Maybe it's the problem of alt_main(), unlike main(), some driver initialization should be added manually. # include "sys/alt_sys_init.h"  in alt_main(): alt_sys_init(); alt_io_redirect (ALT_STDOUT, ALT_STDIN, ALT_STDERR);  I haven't checked myself it yet. but you could try using main() instead if you have enough RAM  Yue