MSP430g2553 Port2 Interrupt is missing

Hi Hamid !

In the example   "  MSP430G2xx3 Demo - Software Port Interrupt Service on P1.4 from LPM4 "

there is a special line

  _BIS_SR(LPM4_bits + GIE);                 // Enter LPM4 w/interrupt

Please, try that -- seems you need the GIE (general interrupt enable) in any case ...

Have fun, Uli

hi,

 by the quick look at the code,,, it looks fine. there are few improvements can be done and as the other poster suggested you have forgot to enable interrupts before entering ion to infinite while loop.

Hamid Khalessi said:

 P2SEL &= ~(BIT0+BIT1+BIT2+BIT3);
    P2DIR &=~(BIT0+BIT1+BIT2+BIT3);
    P2IFG=0x00;
    P2IES &=~(BIT0+BIT1+BIT2+BIT3);
    P2IE |=BIT0+BIT1+BIT2+BIT3;

By default all ports in msp430 work in port configuration mode not in secondary functionality.  So no need to  configure P2SEL regs.

By default all ports are inputs in msp so u only need to configure ports if they are outputs -----------P2DIR

add this intrensic function before while loop and after P2IE configuration _enable_interrupts();        . I think u can c ISR being executed this time. If u dont c it, my advice would be pull any of pins 0,1,2,3 low and c weather ISR is entered.

Regards,

Sri.

Hi Sri,

IT did not help. I could not get into the ISR for PORT2. I even pulled pin 2.0 low and hooked it to ground as you recommended but still my interrupt does not get hit.

Regards,

Dr. Ulrich Kaiser said:

  _BIS_SR(LPM4_bits + GIE);                 // Enter LPM4 w/interrupt

Well, GIE is right. IF GEI is not set, all interrupts are globally disabled, independent of their individual IE bits.
However, setting LPM_bits too will stop the execution of the main thread until an ISR awakens it again. Which doesn't happen.

_bis_SR_register(GIE) or _BIS_SR(GIE) or simply _EINT() or _enable_interrupt() (all do the same) is required before entering the while(1) loop.

sri-sri said:

there are few improvements can be done

Indeed. One of them is to use the same nomenclature throughout the code.

If (P2IFG& TACH_FAN_1) is use inside the ISR, then  P1SEL |= TACH_FAN_1 should be used for the configuration too (and not "BIT0"). Else if the definition of TACH_FAN_1 ever changes, the initialization will not change and cause a problem that is difficult to detect.

However, there are more severe problems: inside the ISR currently the IFG bits for TACH_FAN_3+4 are not deleted. If such an interrupt occurs, the ISR will be called, do nothing, exit and then it will be immediately called again for all eternity (or until next reset/power off). Main will stop executing.
If part of the ISR is deactivated, then part of the initialization (set appropriate IE bits9 should be deactivated too.

Also, before setting the P2IE bits, P2IFG should be cleared. because there might be already some interrupts pending due to previous events or by changing the edge setting.

Then,. with GIE set, it should work.

Hi,

Thanks for ur reply.

I have modified the code to include some of your earlier comments. But still,my break point inside the PORT 2 interrupt does not get hit.Thanks for your help and comments.

The new code :

#define TACH_FAN_1        BIT0
#define TACH_FAN_2        BIT1

#define TACH_FAN_INTS (BIT0+BIT1)

void main(void) {

    static struct timeT timeFlash_FanCheck;
    //static struct timeT timeFanCheck;
    static int ADC_proc;

    //initialize peripheral and other
    WDTCTL=WDTPW+WDTHOLD;      //stop watchdog timer
    low_level_init();
    // Initialize UARTS
    usart0_init();
    timera_init();
    //adc_init();
    initFans();
    P3OUT |= BIT2;    //set to 1
    __bis_SR_register(GIE);
    P1DIR &= ~(BIT6+BIT7);                                // LED Column 0 and 1 off
    P2OUT |= BIT5;                                        // Row 0 off*, RS485 Status Red
    P2DIR |= BIT5;                                        // Row 0 set to output
    P3DIR &= ~(BIT2+BIT3);                                // Rows 2&3 high=off
    P3DIR |= BIT7;                                        // Column 2 Enable output
    P3OUT |= BIT7;                                        // LED Column 2 on
    P2DIR |= BIT4;
    P2OUT &= ~BIT4;                                        // Row 1*, RS485 Status Green
    timeFlash_FanCheck = getTime();
    ADC_proc=VICOR_TEMP;
    //port 2 setup interrupt configuration
    P2IFG=0x00;
    P2IES |= TACH_FAN_INTS;
    P2IE |=TACH_FAN_INTS;
    _enable_interrupts();

    _NOP();
    while(1)
    {

          if (timer(timeFlash_FanCheck,1000))
            {
                timeFlash_FanCheck = getTime();
                readFanSpeed();   //will process TACH variable incremented by port 2 interrupt
                P2OUT ^= BIT4;                            // Row 1*, RS485 Status Green, toggle
            }

}

// Fan Tach PORT2 Interrupt Service Routine
#pragma vector = PORT2_VECTOR
__interrupt void isrPORT2(void)
{
    _NOP();  //Deug only

    //configure port2 pins0,1,2,3 IE in low_level_init()
    if (P2IFG & TACH_FAN_1)        // Tachometer pulse detected ?
    {
        Fans[0].TachCount++;        // Increment tach counter
        P2IFG &= ~TACH_FAN_1;        // Clear interrupt flag
    }

    if (P2IFG & TACH_FAN_2)        // Tachometer pulse detected ?
    {
        Fans[1].TachCount++;        // Increment tach counter
        P2IFG &= ~TACH_FAN_2;        // Clear interrupt flag
    }
}

Please, insert   a command before the NOP in order to toggle the LED.

Can you see any changes at the LED ?

rgds, Uli