Philip Pemberton wrote:
> OK, this is just getting weird...
>
> I had external interrupts working in the JAL prototype of my=20
> remote-control receiver code, but I'm rewriting it in C18 (mainly=20
> because I can do floating-point calculations for timer preload and=20
> threshold values; JAL AIUI only handles integer math).
>
> The thing is, I'm not seeing any interrupts -- none at all. I put a=20
> breakpoint on the "goto ISR" line, and the PIC didn't break. I also=20
> didn't see anything on the logic analyser....
>
> I must be doing something stupid, but I can't for the life of me figure=20
> out what:
>
> #include <p18cxxx.h>
> #pragma config OSC =3D HS     // High Speed Crystal oscillator
> #pragma config WDT =3D OFF    // Watchdog timer off
> #pragma config LVP =3D OFF    // Low-voltage programming off
> #pragma config MCLRE =3D ON   // MCLR (reset) on
> #pragma config FSCM =3D OFF   // Failsafe clock monitor off
>
> // timer0 prescaler settings
> #define TIMER0_USE_PRESCALER
> #define TIMER0_PRESCALER_SETTING 5
>
> // Infra-red receiver
> #define PIN_IR                PORTBbits.RB0
> #define PIN_IR_DIR            TRISBbits.TRISB0
>
> void isr(void);
>
> // ISR stub code
> #pragma code HIGH_INTERRUPT_VECTOR =3D 0x8
> void high_ISR (void)
> {
>      _asm
>          goto isr
>      _endasm
> }
> #pragma code
>
> // Interrupt Service Routine
> #pragma interrupt isr
> void isr(void)
> {
>      unsigned char tval;
>      char overflow;
>
>      // Store timer value and overflow flag and rearm the timer
>      tval =3D TMR0L;
>      TMR0L =3D 0;
>      overflow =3D INTCONbits.TMR0IF;
>      INTCONbits.TMR0IF =3D 0;
>
>      // detect RB0 int flag
>      if (INTCONbits.INT0IF) {
>          char pol;
>
>          // clear interrupt flag
>          INTCONbits.INT0IF =3D 0;
>
>          // store bit polarity, then flip to other polarity
>          pol =3D INTCON2bits.INTEDG0;
>          INTCON2bits.INTEDG0 =3D !INTCON2bits.INTEDG0;
>      }
> }
>
> void main(void)
> {
>      // Initialise pin directions
>      LATA =3D LATB =3D 0;        // Clear port holding registers
>      TRISA =3D TRISB =3D 0;        // Default to all outputs
>      PIN_IR_DIR =3D 1;            // IR pin is an input
>
>      // Set up timer 0
>      T0CON =3D 0;            // Clear timer control register
> #ifdef TIMER0_USE_PRESCALER
>      T0CONbits.PSA =3D 1;        // Assign prescaler to timer0
>      T0CONbits.T0PS0 =3D (TIMER0_PRESCALER_SETTING & 1)=3D=3D1;
>      T0CONbits.T0PS1 =3D (TIMER0_PRESCALER_SETTING & 2)=3D=3D2;
>      T0CONbits.T0PS2 =3D (TIMER0_PRESCALER_SETTING & 4)=3D=3D4;
> #else
>      T0CONbits.PSA =3D 0;        // Disable prescaler
> #endif
>      TMR0L =3D 0;            // Clear timer0 value
>
>      // Set up interrupts
>      INTCON2bits.INTEDG0 =3D IPOL_ACT;    // Trigger RB0 interrupt on
>                      // active-going edge
>      INTCONbits.INT0IF =3D 0;        // Clear RB0 interrupt flag
>      INTCONbits.INT0IE =3D 1;        // Enable INT0 interrupt
>      // The ISR handles the timer-0 overflow interrupt.
>      INTCONbits.GIE =3D 1;        // Enable interrupts (globally)
>
>      debug_word(0xCAFE);
>      debug_word(0xBABE);
>
>      for (;;) {
>      }
> }
>
>
> Can anyone see what I'm doing wrong here?=20

> The chip seems to be acting as=20
> if GIE were never set, but the SFR window suggests it *is* being set (as=
=20
> is INT0IE)...
>  =20
What intterrupts are you expecting? Your code seems to talk about a=20
timer interrupt but doesn't seem to actually enable the timer interrupt.

As for the int0 intterrupt it looks to me like you may have RB0 set as=20
an analog input.

> Thanks,
>  =20

--=20
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