Interrupt Nios II RS232 / Usart

[Altera_Forum]

Hello! 

I am trying to use the rs232 interrupt. sending and receiving data works fine, but when i try to use the interrupt to receive data I get some problems.   this is the rs232 block in my system.h  /*  * uart_rs232 configuration  *  */  # define UART_RS232_NAME "/dev/uart_rs232" # define UART_RS232_TYPE "altera_avalon_uart" # define UART_RS232_BASE 0x0a201280 # define UART_RS232_SPAN 32 # define UART_RS232_IRQ 18 # define UART_RS232_IRQ_INTERRUPT_CONTROLLER_ID 0 # define UART_RS232_BAUD 9600 # define UART_RS232_DATA_BITS 8 # define UART_RS232_FIXED_BAUD 0 # define UART_RS232_PARITY 'N' # define UART_RS232_STOP_BITS 1 # define UART_RS232_SYNC_REG_DEPTH 2 # define UART_RS232_USE_CTS_RTS 0 # define UART_RS232_USE_EOP_REGISTER 0 # define UART_RS232_SIM_TRUE_BAUD 0 # define UART_RS232_SIM_CHAR_STREAM "" # define UART_RS232_RELATIVEPATH 0 # define UART_RS232_FREQ 100000000 # define ALT_MODULE_CLASS_uart_rs232 altera_avalon_uart  //this is my context  typedef struct {  int number; }my_context;    //This is my ISR  void rs232_isr (void* context, alt_u32 interrupt_number) {    printf("data gets in"); }     //this I call in my main at first  void main(){  char msg[4]="test"; int result;  result=alt_irq_register (UART_RS232_IRQ,  (void*)my_contex,  rs232_isr);  alt_irq_enable(UART_RS232_IRQ);   do{     fp = fopen("/dev/uart_rs232", "w+");  if(fp)  {  //printf("Connected\n");  fwrite(msg, strlen(msg), 1, fp);  //fprintf(fp, "Closing the UART file.\n");  fclose(fp);  }  else  {  printf("Error/dev/ttyS0\n");  }           }while(1);   }    If I start the my program the rs232_isr is called I think one hundred times... I think the rs232_isr is called by the fwrite(..). Is there a method to recognize only the RXD without react everytime at TXD (text send).

[Altera_Forum]

Nobody who van help me?

[Altera_Forum]

check this thread. 

 http://www.alteraforum.com/forum/showthread.php?t=13134  It contains also some code samples how to do it.

[Altera_Forum]

I red the other thread and now my isr works, but now the write function does not work..nothing is send, only the RXD comes 

 volatile int counter;   init RXD   /* flush any characters sitting in the holding register */  IORD(UART_RS232_BASE, 0);  IORD(UART_RS232_BASE, 0);  /* reset most of the status register bits */  IOWR(UART_RS232_BASE, 2, 0x00);  /* install IRQ service routine */  alt_irq_register(UART_RS232_IRQ, 0, serial_irq_0);  /* enable irq for Rx. */  IOWR(UART_RS232_BASE, 3, 0x0080);  The ISR is so:   static void serial_irq_0(void* context , alt_u32 id) { unsigned int stat,temp; int chr[3];     // message[0]=getc(fp_read); /* get serial status */  stat = IORD(UART_RS232_BASE, 2);  /* character Rx */  if (stat & 0x0080) {  message [counter]= IORD(UART_RS232_BASE, 0);       }       if(counter==2){  printf("char: %c%c%c",message[0],message[1],message[2]);    counter=0;  }    else  counter++; }         In a Task I wrote this to write:  FILE *fp_write;  fp_write = fopen("/dev/uart_rs232", "w+"); //also used r+  if(fp_write)  {  //printf("Verbunden\n");  fwrite(pic_viewer->message, strlen(pic_viewer->message), 1, fp_write);  OSTimeDlyHMSM(0, 0, 0, (20));  //fwrite(msg,strlen(msg),1,fp);  //sprintf(msg,"%i",400);  //fwrite(msg, strlen(msg),1,fp);  //fprintf(fp, "Closing the UART file.\n");  fclose(fp_write);  sprintf(pic_viewer->message,"%s","00050200");  }  else  {  printf("Error/dev/ttyS0\n");  }

[Altera_Forum]

I am not really sure about your code.  

I would guess message[] is a receive buffer but ... Are you using a mix of standard lib and your own code on the same RS232? I strictly separated then and have no trouble.