Electrical – dsPIC33E External Interrupts INT0,INT1,INT2 not firing

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I have read every post I can find and still do not understand why external interrupts are not triggering, the following is my initialization, it is not clean, as I am in the process of trying everything I can think of to make this work.

To simplify the problem, consider only INT1.

Update: It appears the flag is getting triggered, but the ISR is never being executed. The flag is not being lowered

void __attribute__((__interrupt__, no_auto_psv)) _INT1Interrupt(void)
{
IFS1bits.INT1IF = 0;    //Clear the INT1 interrupt flag 
//U1TXREG='0';

m_Capture1 = 1;

}  




// Hall Sensor A                | Pin 31    RPI24       RA8

// Disable all other pin functionality.
TRISAbits.TRISA8 = 1 ;
//LATAbits.LATA8 = 0;
ODCAbits.ODCA8=0;
CNENAbits.CNIEA8=0;
CNPUAbits.CNPUA8=0;
CNPDAbits.CNPDA8=0;


//INTCON1bits.NSTDIS = 0; // interrupt nesting enabled.
//INTCON2bits.GIE = 1;    // Global Interrupt Enable.

INTCON2 = 0x0000;       // all interrupts on rising edge.       

// Reset Interrupt flags.
IFS0bits.INT0IF = 0;      //Reset INT0 interrupt flag 
IFS1bits.INT1IF = 0;    //Reset INT1 interrupt flag
IFS1bits.INT2IF = 0;    //Reset INT2 interrupt flag

INTCON2bits.INT0EP = 1 ;
INTCON2bits.INT1EP = 1 ;
INTCON2bits.INT2EP = 1 ;

// Enable Interrupts.
IEC0bits.INT0IE = 1;    // Enable INT0 Interrupt Service Routine.
IEC1bits.INT1IE = 1;    // Enable INT1 Interrupt Service Routine. 
IEC1bits.INT2IE = 1;    // Enable INT2 Interrupt Service Routine.

// Set Interrupt Priority.
//IPC5bits.INT1IP = 5;  // If all the IPC bits associated with
                        // an interrupt source are cleared, the interrupt 
                        // source is effectively disabled.
//IPC7bits.INT2IP = 2;  //set low priority
//IPC0bits.INT0IP = 2;  //set low priority
IPC5bits.INT1IP = 4;    /*set low priority*/


RPINR0bits.INT1R |= 24;//0x18; //001 1000;    // Set Hall A - RPI24/RA8 set                     INT1
RPINR1bits.INT2R |= 51;//0x33; //011 0011     // Set Hall B = RPI51/RC3 set INT2
// Hall C RP39/RB7 is INT0 (not mappable)

I have verified with 100% certainty that the voltage on the pin is changing from 0 to 3.3V. Any help is appreciated.

Thanks,
Gary

Best Answer

At this point I feel fairly certain the problem was the line

 INTCON2 = 0x0000;

which effectively disabled bit 15 (global interrupt enable). The following is a working initialization function.

void BldcHallSensorInit( void )
{
// Hall Sensor A                | Pin 31    RPI24       RA8     INT2
// Hall Sensor B                | Pin 35    RPI51       RC3     INT1
// Hall Sensor C                | Pin 46    RP39        RB7     not mappable


TRISAbits.TRISA8 = 1 ;
TRISCbits.TRISC3 = 1 ;

RPINR0bits.INT1R = 51;  //001 1000;     // Set Hall B = RPI51/RC3 set INT2
RPINR1bits.INT2R = 24;  //011 0011      // Set Hall A - RPI24/RA8 set INT1 


//CORCONbits.IPL3 = 0;
//INTCON1bits.NSTDIS = 0; // interrupt nesting enabled.
//INTCON2bits.DISI = 0 ;
//INTCON2bits.SWTRAP = 0 ;

//INTCON2 = 0x0000;       // **erroneous line**       

// Reset Interrupt flags.
IFS0bits.INT0IF = 0;      //Reset INT1 interrupt flag 
IFS1bits.INT1IF = 0;    //Reset INT0 interrupt flag
IFS1bits.INT2IF = 0;    //Reset INT0 interrupt flag

// Interrupt edge polarity.
INTCON2bits.INT0EP = 1 ;
INTCON2bits.INT1EP = 1 ;
INTCON2bits.INT2EP = 1 ;

// Set Interrupt Priority.
IPC0bits.INT0IP = 1;    // set low priority.
IPC5bits.INT1IP = 1;    // set low priority.
IPC7bits.INT2IP = 1;    // set low priority.

// Enable Interrupts.
IEC0bits.INT0IE = 1;    // Enable INT0 Interrupt Service Routine.
IEC1bits.INT1IE = 1;    // Enable INT1 Interrupt Service Routine. 
IEC1bits.INT2IE = 1;    // Enable INT2 Interrupt Service Routine.

INTCON2bits.GIE = 1;    // Global Interrupt Enable. Order/placement of this
                        // line is important.
}

Related Solutions

Electronic – How does writing to output pins on PORTB affect RBIF interrupt on PIC16F877

The mismatch condition will set the interrupt flag, and reading the port removes the mismatch, but doing so does not clear the flag, you must still clear it manually inside the isr.

From port B circuitry shown in the datasheet (Figure 3-4) you can tell that there is no way that WR (asserted during port writes) could remove the mismatch when the pin is configured as an input (TRIS bit is 1), because the WR signal does not affect anything but the "Data Latch", and the output of the data latch doesn't go anywhere because the tri-state buffer is in high impedance when the TRIS bit is 1.

The information missing here is that a port write also triggers port read, because all writes are really read-modify-write operations. The datasheet says this explicitly about port A, but I suspect it works the same way on port B. This means that when you write to the port, a read is actually performed as well, so RD is asserted, removing the mismatch.

However, the mismatch being removed when you write to the port does not affect the fact that the interrupt is called, because the flag is still set, which is the only thing you need to worry about. Your code does not change, you would still perform a read and then clear the flag when you enter the isr.

You may be wondering if a read or a read-modify-write operation occurs at exactly the same time as the input change may make it miss a mismatch condition. It does not, the flag is should still be set. This is because of the input latch controlled by a signal Q1 (which is not mentioned in the text). It basically keeps the input value for the mismatch comparison during the part of the read cycle in which the RD is being asserted, so that the mismatch is still caught.

AVR global variable modified by interrupt not persistant

There is an infinite loop inside FadeOnLED(). Once INT1 is triggered, it will take your main() inside FadeOnLED() and as it contains while(1) there is no way out of it. So your main program flow will be stuck inside the infinite loop of FadeOnLED(). After that, other interrupts can shorty interrupt the work of this infinite loop(where your main program flow is), but will not get out (break) of it.

One possible solution (not very nice, but just to show the idea) is to use the following:

void FadeOnLed(void)
{
    GREEN   = 0;
    BLUE    = 0;
    RED     = 90;

    //see led_delay for led delay time
    //RED is defined as 1, GREEN as 2, BLUE as 3 when passing values to function
    while (display_select == 0x01)
    {
        ...
    }
}

Best Answer

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Electronic – How does writing to output pins on PORTB affect RBIF interrupt on PIC16F877

AVR global variable modified by interrupt not persistant

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