interrupt on change notification

[jpc]

I am trying to get an interrupt on change and somehow do not succeed
This is my testprogram , i am using here 30F3012 chip on Easydspic2 .
What is missing / wrong as it never interrupt's

Code: Select all

Program Cnint1;
// Input Change Notification Interrupt

Procedure Cn_interrupt; Org $32;
Var Dum : Word;
Begin
  latd := 1;      // should turn LED on at first interrupt occurring
  Dum := PORTb;
  //IFS0.15 := 0; // Clear Flag

End;

Procedure Init;
Var Dum : Word;
Begin
  TRISB := $ffff; // All Inputs
  PORTD := $0;
  TRISD := 0;
  TRISC := 0;
  CNEN1 := %0000000000000100;  // Allow Interrrupts On  Cn2 Input which is RB0 also

  IPC3.14 := 1;  //
  IPC3.13 := 1;  // Give High Priority
  IPC3.12 := 1;  //

  IFS0.15 := 0;  // Clear Cn-interrupt Flag
  IEC0.15 := 1;  // Allow Cn-interrupts

End;

Begin
delay_ms(100);
  Init;
  While True Do
  Begin
    Delay_ms(300);
    PORTc.15 := PORTc.15 Xor 1;  // flashing LED to have some sign of life
  End;
End.

[zristic]

You should try to turn off ADC on PORTB. I did not check the datasheet, but as far as I remember you should set the ADPCFG register, to 0xFFFF I think.

[jpc]

Right you are , i overlooked something in the datasheet :

Note: In order to use PORTB pins for digital I/O, the corresponding bits in the ADPCFG
register must be set to ‘1’, even if the A/D module is turned off.

now it starts working the way i wanted , Thanks Zoran!

[zristic]

Thanks Zoran!

Anytime.

[steve42lawson]

I was having the same problem with a PIC24FJ32GA002. I had set the appropriate CNEN1bits, but what I overlooked was the need to set the CNIE bit:

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IEC1bits.CNIE = 1;

Or, if you're into bit fiddling:

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IEC1 = IEC1 | 0x0008;

Also, make sure the interrupt priorities are correctly set (IPC4bits.CNIP0-2). The CN interrupt priority needs to be higher (larger number) than the CPU priority. The CPU priority is set to zero on reset, so unless you changed that, you should be good to go "out of the box" (so to speak )

BTW: I'm not sure about this, but if you have more than one interrupt going and if any of them have the same priority level as the CN interrupt, then the state of the INTCON1bits.NSTDIS bit may be important.