NVIC SAMPLE

/* 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;            /* suppress compiler warning "unused variable" */

}

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");

}