INTERRUPTS- PIC16F877A

Replies

• 

  lal

  Yes, you can. For all the interrupts, PC will point to 04h and you will need to further check the flags to see what action caused interrupt and execute instructions corresponding to that.
• 

  raja_karthick

  lal

  Yes, you can. For all the interrupts, PC will point to 04h and you will need to further check the flags to see what action caused interrupt and execute instructions corresponding to that.

  yep. i tried it using mikroc and i got a perfect output in proteus simulation. but for the same code, the ic does not responds. there is some real time issue
• 

  raja_karthick

  raja_karthick

  yep. i tried it using mikroc and i got a perfect output in proteus simulation. but for the same code, the ic does not responds. there is some real time issue

• 

  raja_karthick

  this is my code. what could be my possible issue??
  ***********************************************************************
  int count=0; //initialise count variable
  int a; //initialise temp variable
  void motor()
  {
  //consider RD0 and RD1 be input to motors
  PORTC.F0=1;
  PORTC.F1=0; //door open
  Delay_ms(5000);
  PORTC.F0=0;
  PORTC.F1=0; //door stop
  Delay_ms(20000);
  PORTC.F0=0;
  PORTC.F1=1; //door close
  Delay_ms(5000);
  PORTC=0X00;
  PORTC.F6=0; //rf low signal
  }
  
  void main()
  {
  //general register direction configuration
  TRISC=0X00;
  TRISD=0XFF;
  //general port configuration
  PORTC=0X00;
  PORTD=0X00;
  OPTION_REG.INTEDG = 1; //rising egde is taken as interrupt
  INTCON.GIE = 1;//enable global interrupt (INTCON is interrupt register)
  INTCON.INTE = 1;//enable external interrupt pin i.e RB0
  INTCON.RBIE = 1;//enable port change interrupt in port B (pins 4 to7)
  while(1)
  {
  if(PORTD.F0==1) //RFID TRUE VALUE
  {
  while(PORTD.F0); //hold the value
  PORTC.F6=1; //RD3 be RF at engine
  motor(); //function call
  }
  }
  }
  //interrupt service routine
  void interrupt()
  {
  
  if(INTCON.INTF==1) //check rb0 int flag
  {
  count++; //increment count
  INTCON.INTF=0; //clear rb0 int flag
  }
  if(INTCON.RBIF==1) //check rb port change int flag
  {
  while(PORTB.F4==1); //hold the value
  count--; //decrement count
  a=PORTB; //read portb to eliminate mismatch conditon after triggering
  INTCON.RBIF=0; //clear rb port change int flag
  }
  if (count>2)
  {
  PORTC.F7=1; //send high pulse to 2nd rf pin
  }
  else if(count<=2)
  {
  PORTC.F7=0; //send low pulse to 2nd rf pin
  }
  
  
  }
  ***********************************************************************
• 

  lal

  I cannot comment on the code. I never had experience coding in MikroC. I write in assembly.
  
  By the way, does PIC respond to external interrupt?
• 

  Harshad Italiya

  Not 100% sure as I have to look into datasheet for that more but if you have enabled,
  
  Pin Change Notification and EXT interrupt together.
  Means you are getting EXT interrupt when pin goes HIGH or LOW and you also get interrupt when status of the pin change So it should trigger both interrupt but you also have to check about priority.
• 

  raja_karthick

  lal

  I cannot comment on the code. I never had experience coding in MikroC. I write in assembly.
  
  By the way, does PIC respond to external interrupt?

  yep, it responds sometimes with issues like a delayed output when checked with a simple blink program, but for the code mentioned above, there is no response from the pic, even the main function does not occur
• 

  raja_karthick

  Harshad Italiya

  Not 100% sure as I have to look into datasheet for that more but if you have enabled,
  
  Pin Change Notification and EXT interrupt together.
  Means you are getting EXT interrupt when pin goes HIGH or LOW and you also get interrupt when status of the pin change So it should trigger both interrupt but you also have to check about priority.

  i am using two different flags for RB0 and PORT change interrupt and checking them with a "if" condition. and also pin change interrupts occur only in pins RB4 to RB7. EXT interrupt occurs at RB0.
• 

  Harshad Italiya

  raja_karthick

  yep. i tried it using mikroc and i got a perfect output in proteus simulation. but for the same code, the ic does not responds. there is some real time issue

  Ok, Then you might check with the hardware you have. when you are changing the input pin have you measured with DMM if that pin really goes HIGH or LOW or not?
  Also one more point you might have to look have you configured your that Pin in Input direction or not. From above code it is not looking like you have make it input. It's worth trying to setup as input along with measuring with DMM if it is switching the logic HIGH and LOW really or not.
• 

  raja_karthick

  Harshad Italiya

  Ok, Then you might check with the hardware you have. when you are changing the input pin have you measured with DMM if that pin really goes HIGH or LOW or not?
  Also one more point you might have to look have you configured your that Pin in Input direction or not. From above code it is not looking like you have make it input. It's worth trying to setup as input along with measuring with DMM if it is switching the logic HIGH and LOW really or not.

  I will try configuring the direction flow of register and also the DMM and then i will reply😀