John Mazzei

KBI interrupt problem on AW60

Discussion created by John Mazzei on Apr 1, 2008
Latest reply on Apr 1, 2008 by John Mazzei
Hello everyone,
I am experiencing a problem with the KBI interrupt on an AW60 microcontroller.
The interrupt is enabled on the falling edge of KBIP0 (PTG0) by an init routine.
On the occurrance of the interrupt a pin toggle is executed.
Here are the routines:
void KBIInit(void)
    KBI1PE = 0b00000001;    /* interrupt on KBI0 */           
    KBI1SC = 0b00000100;    /* KBEDGE7..4 --> 0 (don't care) */
                                              /* KBF --> 0 (read only) */
                                              /* KBACK --> 1 (reset KBF) */
                                              /* KBIE --> 0 (interrupt disabled) */
                                              /* KBIMOD --> 0 (only edge detection) */
    KBI1SC = 0b00000110;   /* KBI interrupt enable */
#pragma TRAP_PROC
void KbiIntHandler (void)
    if (KBI1SC_KBF)
       OUPUT = !OUPUT;            //pin toggle
        KBI1SC_KBACK = 1;        /* ACK to reset interrupt flag */
The input signal on the KBI pin is a square ware with frequency approx 50Hz.
I would expect to see a 50 Hz pin toggle on the output pin.
What happenes is that some times (quite often) as soon as the interrupt procedure is exited it is entered again so I see a pin toggle 10 usec after the previous one.
Thank you,