View source for Tiva sw1 int source

__NOTOC__
==  sw1_int.c ==

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/* sw1_int.c
 *
 * Runs on EK-TM4C123GXL LaunchPad
 *
 * GPIO PORTF interrupt that will toggle the on board Blue LED
 * on rising edge whenever a user switch (SW1) is pressed.
 *
 */
#include <stdint.h>
#include "inc/tm4c123gh6pm.h"

void DisableInterrupts(void);
void EnableInterrupts(void);
void WaitForInterrupt(void);
void GPIOPortF_Init(void);
void GPIOPortF_Handler(void);

void GPIOPortF_Init(void)
{

    SYSCTL_RCGC2_R |= 0x00000020;   /* 1) activate clock for Port F */

    GPIO_PORTF_LOCK_R = 0x4C4F434B; /* 2) unlock GPIO Port F */
    GPIO_PORTF_CR_R = 0x1F;         /* allow changes to PF4-0 */
    GPIO_PORTF_AMSEL_R = 0x00;      /* 3) disable analog on PF */
    GPIO_PORTF_PCTL_R = 0x00000000; /* 4) PCTL GPIO on PF4-0 */
    GPIO_PORTF_DIR_R = 0x0E;        /* 5) PF4,PF0 in, PF3-1 out */
    GPIO_PORTF_AFSEL_R = 0x00;      /* 6) disable alt funct on PF7-0 */
    GPIO_PORTF_PUR_R = 0x11;        /* enable pull-up on PF0 and PF4 */
    GPIO_PORTF_DEN_R = 0x1F;        /* 7) enable digital I/O on PF4-0 */

    GPIO_PORTF_IS_R &= ~0x10;       /*  PF4 is edge-sensitive */
    GPIO_PORTF_IBE_R &= ~0x10;      /*  PF4 is not both edges */
    GPIO_PORTF_IEV_R &= ~0x10;      /*  PF4 falling edge event */
    GPIO_PORTF_ICR_R = 0x10;        /*  Clear flag4 */
    GPIO_PORTF_IM_R |= 0x10;        /*  arm interrupt on PF4 */
    NVIC_PRI7_R = (NVIC_PRI7_R & 0xFF1FFFFF) | 0x00A00000; /*  priority 5 */
    NVIC_EN0_R = 0x40000000;        /*  Enable interrupt 30 in NVIC */

    EnableInterrupts();             /* Enable global Interrupt flag (I) */
}

void GPIOPortF_Handler(void)
{
    volatile int readback;

    GPIO_PORTF_ICR_R = 0x10;        /* clear PF4 int */
    GPIO_PORTF_DATA_R ^= (1<<2);    /* toggle Blue LED */
    readback = GPIO_PORTF_ICR_R;    /* a read to force clearing of interrupt flag */
    readback = readback;
}

int main(void)
{
    GPIOPortF_Init();               /* initialize GPIO Port F interrupt */

    while(1) {
        WaitForInterrupt();
    }
}

/*********** DisableInterrupts ***************
*
* disable interrupts
*
* inputs:  none
* outputs: none
*/

void DisableInterrupts(void)
{
    __asm ("    CPSID  I\n");
}

/*********** EnableInterrupts ***************
*
* emable interrupts
*
* inputs:  none
* outputs: none
*/

void EnableInterrupts(void)
{
    __asm  ("    CPSIE  I\n");
}

/*********** WaitForInterrupt ************************
*
* go to low power mode while waiting for the next interrupt
*
* inputs:  none
* outputs: none
*/

void WaitForInterrupt(void)
{
    __asm  ("    WFI\n");
}
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