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#int_rda happens sometimes only once

 
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mdemuth



Joined: 16 Apr 2007
Posts: 71
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#int_rda happens sometimes only once
PostPosted: Tue Nov 02, 2010 10:37 am     Reply with quote

Hi there,

I am using the compiler version 4.114

I am trying to read a stream via the uart. Each received character is supposed to create an IRQ an then it should be written into a stream (array).

The PC sends messages every 0.5s.

Sometimes everything works fine, but sometimes (50%) the programm only gets a single IRQ (I count the IRQs with the LED_3 variable) and then no more characters are received.

Has anybody an idea?

Thanks in advance,

Michael
Code:

#include <18f2580.h>      //
#device ADC=10 //
#device HIGH_INTS=TRUE
// #device ICD=TRUE
// #fuses INTRC_IO,NOWDT,NOPROTECT,BROWNOUT,PUT,MCLR // Kein WDT


#fuses INTRC_IO,NOWDT,NOPROTECT,BROWNOUT,PUT,MCLR, BORV28
#use delay(clock=32000000)

#use fast_io(A)
#use fast_io(B)
#use fast_io(C)

#use rs232(stream=COM1, baud=19200,PARITY=N, BITS=8, STOP=1, UART1) //
#use rs232(stream=COM2, baud=9600,XMIT=PIN_C1) //
#use i2c (master, sda=PIN_C4, scl=PIN_C3, FORCE_HW, FAST)
....


// RS232 Schnittstelle
#define RX_BUFFER_LENGTH 35 // STX,ETX,ID,BCC +  maximal 30 Byte Nutzdaten
char rx_buffer[RX_BUFFER_LENGTH];
int  rx_buffid;

..

   setup_oscillator (OSC_32MHZ);
   SETUP_ADC_PORTS(AN0_TO_AN1);
   SETUP_ADC(ADC_CLOCK_INTERNAL);
   
   SETUP_WDT(WDT_OFF);   //WDT
   RESTART_WDT();      // Initialisierung
   
   set_tris_a(0b00000011);   //
   set_tris_b(0b00110000);   //
   set_tris_c(0b10011000);   //

   setup_ccp1(CCP_PWM);   // Configure CCP1 as a PWM
   setup_timer_2(T2_DIV_BY_16, 250, 1);

   seriennummer_LB=read_EEPROM (0);
   seriennummer_HB=read_EEPROM (1);
   seriennummer = make16(seriennummer_HB,seriennummer_LB);

   output_low(LE);     // init LED Drivers
   output_low(OUT_ENABLE);     //
   output_low(SDO);     //
   output_low(SCK);     //
  ...

setup_uart(19200,COM1);
enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA); // Empfangs IRQ aktivieren

 

while(1) // Test
  {
   
  counter16++;
  if (bit_test(counter16,9)) LED_RX = true;
  else LED_RX = false;
  Set_LEDs();
  Read_Keyboard();
  if (rx_complete == 2)
    {
   
    rx_complete =0;
    fputc(0x06,COM1); // Ack senden
    // fputc(0x0C,COM2); // Formfeed
    // fprintf(com2,"%03u",i);
    //for (i=0; i < RX_BUFFER_LENGTH;i++) fprintf(com2," %03u",RX_BUFFER[i]);  //
    for (i=0; i < 20;i++) fprintf(com2, " %03x" RX_BUFFER[i]);
     
       
    }
  for (i=0; i < 20;i++) RX_BUFFER[i]=0; 
   
  }


#INT_RDA
void IRQ_UART(void)
    {
     character = fgetc(com1);      // Character in den Puffer
   


    if (character == 0x02 && rx_complete == 0) rx_buffid = 0;   // Bei Empfang von STX Pointer zurücksetzen
    else  rx_buffid++; // Zeiger inkrementieren
   
    if (rx_buffid >= RX_BUFFER_LENGTH) rx_buffid = RX_BUFFER_LENGTH;  // Überlauf abfangen
   
    rx_buffer[rx_buffid]=character;
    if (rx_complete == 1) rx_complete = 2; // Empfang von Zeichen nach dem erstem ETX beendet den Telegrammempfang
    if (character == 0x03 && rx_complete==0) rx_complete=1;   // Empfang von erstem ETX merken
   
    led_3++; // just for debugging....
    }
Ttelmah



Joined: 11 Mar 2010
Posts: 19545

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PostPosted: Tue Nov 02, 2010 11:07 am     Reply with quote

You are probably overflowing the buffer.
Your array, has addresses 0 to 34.
You limit the access address to 35.
When you write to location 35, you will overwrite the 'rx_buffid' variable, and failure will result.

You need:
Code:

    if (rx_buffid >= RX_BUFFER_LENGTH) rx_buffid = RX_BUFFER_LENGTH-1;  // Überlauf abfangen

Note the '-1'.....

Best Wishes
pmuldoon



Joined: 26 Sep 2003
Posts: 218
Location: Northern Indiana

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PostPosted: Wed Nov 03, 2010 8:11 pm     Reply with quote

You might also want to add ERRORS to your directives:
Code:

#use rs232(stream=COM1, baud=19200,PARITY=N, BITS=8, STOP=1, UART1,ERRORS) //
#use rs232(stream=COM2, baud=9600,XMIT=PIN_C1,ERRORS) //


otherwise your UARTS will halt on errors.
mdemuth



Joined: 16 Apr 2007
Posts: 71
Location: Stuttgart, Germany

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problem solved
PostPosted: Thu Nov 04, 2010 5:18 am     Reply with quote

Idea
The "ERRORS" added to the directive solved the problem, thanks for good support!
Very Happy
Douglas Kennedy



Joined: 07 Sep 2003
Posts: 755
Location: Florida

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PostPosted: Thu Nov 04, 2010 12:27 pm     Reply with quote

ERRORS is almost a required parameter. It is the way it is but you could argue the parameter should have been NO_ERROR_RECOVERY indicating you wanted the interface to crash on any error. The default maybe should have been the same as adding ERRORS since that is what most would want.

RS232 is vulnerable to errors both from the environment and from its asynchronous nature. There isn't much you can do with a RS232 error except log it unless you build in ACK NAK flags so the RS232 sender can resend.
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