gpio_ex2_inputInterrupt.c

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/*******************************************************************************
 * MSP430i2xx GPIO - Input Interrupt
 *
 * Description: In this example, P1.4 is setup as an output pin. P2.0 is set up
 * as an input pin that interrupts when the voltage applied goes from high to
 * low. When the voltage transition happens the ISR is fired and P1.4 is
 * toggled to show that an interrupt happened. If P2.0 is still low then the
 * interrupt edge is switched to trigger when P2.0 goes from low to high. This
 * way an interrupt occurs on every voltage change of P2.0.
 *
 *
 *                MSP430i2041
 *             ------------------
 *         /|\|                  |
 *          | |                  |
 *          --|RST           P2.0|<--Input Signal
 *            |                  |
 *            |                  |
 *            |              P1.4|-->LED
 *            |                  |
 *            |                  |
 *
 * Author: Zack Lalanne
 ******************************************************************************/
 
#include "driverlib.h"
 
int main(void) {
 
    WDT_hold(WDT_BASE);
 
    // Set P1.4 as output pin to drive the LED
    GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN4);
 
    // Setup P2.0 to interrupt on High to Low transition
    GPIO_setAsInputPin(GPIO_PORT_P2, GPIO_PIN0);
    GPIO_selectInterruptEdge(GPIO_PORT_P2, GPIO_PIN0,
                             GPIO_HIGH_TO_LOW_TRANSITION);
    GPIO_clearInterrupt(GPIO_PORT_P2, GPIO_PIN0);
    GPIO_enableInterrupt(GPIO_PORT_P2, GPIO_PIN0);
 
    // Go into LPM0 with interrupts enabled
    __bis_SR_register(LPM0_bits | GIE);
}
 
#if defined(__TI_COMPILER_VERSION__) || defined(__IAR_SYSTEMS_ICC__)
#pragma vector=PORT2_VECTOR
__interrupt
#elif defined(__GNUC__)
__attribute__((interrupt(PORT2_VECTOR)))
#endif
void PORT2_ISR(void) {
 
    switch(__even_in_range(P2IV, 0x10)){
        case 0x00: break;               // No interrupt
        case 0x02:                      // P2.0 interrupt
            // Check current state of P2.0 and set correct interrupt edge to occur
            if(GPIO_getInputPinValue(GPIO_PORT_P2, GPIO_PIN0) == GPIO_INPUT_PIN_HIGH) {
                GPIO_selectInterruptEdge(GPIO_PORT_P2, GPIO_PIN0,
                                         GPIO_HIGH_TO_LOW_TRANSITION);
            } else {
                GPIO_selectInterruptEdge(GPIO_PORT_P2, GPIO_PIN0,
                                         GPIO_LOW_TO_HIGH_TRANSITION);
            }
 
            // Toggle 1.4 to indicate an interrupt occurred
            GPIO_toggleOutputOnPin(GPIO_PORT_P1, GPIO_PIN4);
            break;
        case 0x04: break;               // P2.1 interrupt
        case 0x06: break;               // P2.2 interrupt
        case 0x08: break;               // P2.3 interrupt
        case 0x0A: break;               // P2.4 interrupt
        case 0x0C: break;               // P2.5 interrupt
        case 0x0E: break;               // P2.6 interrupt
        case 0x10: break;               // P2.7 interrupt
    }
}