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MSP430F1122 Positive to Negative Edge detection program error

Aakash Patel
Prodigy 65 points
Other Parts Discussed in Thread: MSP430F1122

Below find code for which I have written for detection of positive to negative edge for MSP430F1122.

#include <msp430.h>

int main(void)
{
WDTCTL = WDTPW | WDTHOLD; // Stop watchdog timer
__enable_interrupt(); //Enable interrupt
P1DIR |= 0x01;
P2DIR &= ~0x01; //P2.0 as input port
P2SEL &= ~0x01;// P2.0 as I/O pin for detection of falling edge
P2IE |= 0x01; // P2.0 INTERRUPT ENABLE
P2IES |= 0x01; //P2.0 port will detect pos to neg edge
for (;;) // polling P2.0
{
volatile unsigned int i;
if (P2IFG == 1 )
{
P2IFG &= ~0x01; //Clear Interrupt after trigger.
P1OUT |= 0x01; // P1.0 LED Will be ON for a while

i = 500; // Delay
do (i--);
while (i != 0);


}
else
{
P1OUT &= ~0x01; // P1.0 LED remains off

}
}

return 0;
}

But it does not give me result. Why this simple detection of edge is not

giving me output ?

  • 0
    Guru 23000 points

    Aakash Patel said:
    Why this simple

    Well I think you wants to make it simple for yourself by not reading the datasheet, user manuals or studying the examples and expect the compiler/MCU will do this for you but sorry they wouldn’t!

    Aakash Patel said:
    P2IE |= 0x01; // P2.0 INTERRUPT ENABLE

    Enabling the port interrupt without ISR is danger but lucky you are not setting the GIE bit.

    Aakash Patel said:

    LED Will be ON for a while

    i = 500; // Delay
    do (i--);
    while (i != 0);

    You might have sharp eyes but probably not that fast, a delay of 500 cycles is about 500uS and then the LED goes off again.

  • 0 in reply to Leo Bosch
    Intellectual 610 points

    Its done by writing ISR :

     

    #pragma vector=PORT2_VECTOR

    __interrupt void PORT2_ISR(void)

    {

           P2IFG &= ~0x01;                     //Clear Interrupt after trigger.

           P1OUT ^= 0x01;                          // Toggle P1.0 using exclusive-OR

    }

    Thank you

  • 0 in reply to Jehan Patel
    Guru 74080 points

    Hey you two Patels :-)


    Same last name - same problem?

    http://e2e.ti.com/support/microcontrollers/msp430/f/166/t/356708.aspx

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