> OK, this is just getting weird...
>
> I had external interrupts working in the JAL prototype of my
> remote-control receiver code, but I'm rewriting it in C18 (mainly
> because I can do floating-point calculations for timer preload and
> threshold values; JAL AIUI only handles integer math).
>
> The thing is, I'm not seeing any interrupts -- none at all. I put a
> breakpoint on the "goto ISR" line, and the PIC didn't break. I also
> didn't see anything on the logic analyser....
>
> I must be doing something stupid, but I can't for the life of me figure
> out what:
>
> #include <p18cxxx.h>
> #pragma config OSC = HS     // High Speed Crystal oscillator
> #pragma config WDT = OFF    // Watchdog timer off
> #pragma config LVP = OFF    // Low-voltage programming off
> #pragma config MCLRE = ON   // MCLR (reset) on
> #pragma config FSCM = 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 = 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 = TMR0L;
>      TMR0L = 0;
>      overflow = INTCONbits.TMR0IF;
>      INTCONbits.TMR0IF = 0;
>
>      // detect RB0 int flag
>      if (INTCONbits.INT0IF) {
>          char pol;
>
>          // clear interrupt flag
>          INTCONbits.INT0IF = 0;
>
>          // store bit polarity, then flip to other polarity
>          pol = INTCON2bits.INTEDG0;
>          INTCON2bits.INTEDG0 = !INTCON2bits.INTEDG0;
>      }
> }
>
> void main(void)
> {
>      // Initialise pin directions
>      LATA = LATB = 0;        // Clear port holding registers
>      TRISA = TRISB = 0;        // Default to all outputs
>      PIN_IR_DIR = 1;            // IR pin is an input
>
>      // Set up timer 0
>      T0CON = 0;            // Clear timer control register
> #ifdef TIMER0_USE_PRESCALER
>      T0CONbits.PSA = 1;        // Assign prescaler to timer0
>      T0CONbits.T0PS0 = (TIMER0_PRESCALER_SETTING & 1)==1;
>      T0CONbits.T0PS1 = (TIMER0_PRESCALER_SETTING & 2)==2;
>      T0CONbits.T0PS2 = (TIMER0_PRESCALER_SETTING & 4)==4;
> #else
>      T0CONbits.PSA = 0;        // Disable prescaler
> #endif
>      TMR0L = 0;            // Clear timer0 value
>
>      // Set up interrupts
>      INTCON2bits.INTEDG0 = IPOL_ACT;    // Trigger RB0 interrupt on
>                      // active-going edge
>      INTCONbits.INT0IF = 0;        // Clear RB0 interrupt flag
>      INTCONbits.INT0IE = 1;        // Enable INT0 interrupt
>      // The ISR handles the timer-0 overflow interrupt.
>      INTCONbits.GIE = 1;        // Enable interrupts (globally)
>
>      debug_word(0xCAFE);
>      debug_word(0xBABE);
>
>      for (;;) {
>      }
> }
>
>
> Can anyone see what I'm doing wrong here?
> The chip seems to be acting as
> if GIE were never set, but the SFR window suggests it *is* being set (as
> is INT0IE)...
>   What intterrupts are you expecting? Your code seems to talk about a timer interrupt but doesn't seem to actually enable the timer interrupt.

> OK, this is just getting weird...
>
> I had external interrupts working in the JAL prototype of my
> remote-control receiver code, but I'm rewriting it in C18 (mainly
> because I can do floating-point calculations for timer preload and
> threshold values; JAL AIUI only handles integer math).
>
> The thing is, I'm not seeing any interrupts -- none at all. I put a
> breakpoint on the "goto ISR" line, and the PIC didn't break. I also
> didn't see anything on the logic analyser....
>
> I must be doing something stupid, but I can't for the life of me figure
> out what:
>
> #include <p18cxxx.h>
> #pragma config OSC = HS     // High Speed Crystal oscillator
> #pragma config WDT = OFF    // Watchdog timer off
> #pragma config LVP = OFF    // Low-voltage programming off
> #pragma config MCLRE = ON   // MCLR (reset) on
> #pragma config FSCM = 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 = 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 = TMR0L;
>      TMR0L = 0;
>      overflow = INTCONbits.TMR0IF;
>      INTCONbits.TMR0IF = 0;
>
>      // detect RB0 int flag
>      if (INTCONbits.INT0IF) {
>          char pol;
>
>          // clear interrupt flag
>          INTCONbits.INT0IF = 0;
>
>          // store bit polarity, then flip to other polarity
>          pol = INTCON2bits.INTEDG0;
>          INTCON2bits.INTEDG0 = !INTCON2bits.INTEDG0;
>      }
> }
>