Interrupt using Cortex m4

This blog post explains interrupt programming with cortex m4 development board

Steps to Configure Interrupt

1. Configure pin P2.10 as EINT0 pin using IOCON register P2_10
2. Configure the pin P2.10 as input
3. Select edge triggering mode and select falling edge
4. Enable interrupt and Set Priority
5. Clear the Interrupt Flag initially
6. Go to the interrupt service routine and do some task
7. Clear the Interrupt

Interrupt using Cortex m4 -C Source code

#include "LPC407x_8x_177x_8x.h"

unsigned int count=0;

void delay_ms(long ms);
void Init_LED(void);
void Init_EINT0(void);

void EINT0_IRQHandler(void)
{
  //6. the interrupt service routine 
  LPC_SC->EXTINT  |= 1;     //7. Clear Interrupt flag
  count++;
  while((LPC_GPIO2->PIN & 0x400)==0);
}

int main(void)
{
  Init_LED(); 
  Init_EINT0();
  while(1)
  {
   LPC_GPIO4->PIN = count;
  }
}

void delay_ms(long ms)      // delay 1 ms per count @ CCLK 120 MHz
{
  long i,j;
  for (i = 0; i < ms; i++ )
  for (j = 0; j < 26659; j++ );
}

void Init_LED(void)
{
  //Set the PCGPIO bit
  LPC_SC->PCONP |= (1<<15);
 
  //Configure pins P4.0 to P4.7 as GPIO pins
  LPC_IOCON->P4_0 = 0;
  LPC_IOCON->P4_1 = 0;
  LPC_IOCON->P4_2 = 0;
  LPC_IOCON->P4_3 = 0;
  LPC_IOCON->P4_4 = 0;
  LPC_IOCON->P4_5 = 0;
  LPC_IOCON->P4_6 = 0;
  LPC_IOCON->P4_7 = 0;
 
  //Configure the pins P4.0 to P4.7 as output
  LPC_GPIO4->DIR= 0xFF;
}

void Init_EINT0(void)
{
  //1. Configure pin P2.10 as EINT0 pin
  LPC_IOCON->P2_10 = 1;
 
  //2. Configure the pin P2.10 as input
  LPC_GPIO2->DIR  &= ~(1<<10);
     
  //3. Select Edge Triggering Mode and Select Falling Edge
  LPC_SC->EXTMODE = 1;       
  LPC_SC->EXTPOLAR= 0;
 
  //4. Enable Interrupt and Set Priority
  NVIC->ISER[0] |= (1<<18);     //Enable EINT0
  NVIC->IP[4]   |= (0x3<<19);    //Interrupt Priority 0-High, 31-low  
 
  //5. Clear Interrupt Flag
  LPC_SC->EXTINT  = 1; 
}