s3c2440 external interrupt button implementation

According to the schematic diagram of the TQ2440 development board, the buttons are connected to the EINT0, 1, 2, and 4 pins of the S3C2440 that can be used for external interrupts, and GPFCON can set the functions of these pins.

The EXTINT0 register can set the conditions for the interrupts of these four pins. It should be noted that EINT0~2 have their own interrupt vectors, while EINT4~7 share an interrupt vector.

Therefore, when using EINT4, you must also open the corresponding interrupt enable bit in the EINTMASK register, and after entering the EINT4 interrupt, you must also clear the interrupt bit of the EINTPEND register.

The following is the flowchart of the interrupt handling function. The implementation methods of these four buttons are the same:

Here is the procedure:

/*******************************
    s3c2440 external interrupt button experiment
    LHG
********************************/
#include "2440addr.h"

#include "eint_button.h"
#include "uart.h"

#define U32 unsigned int


int button_result;//Record which button is pressed

int get_button_result(void)//Get the button
{
    int b;
    switch(button_result)//Switch out the correct button number
    {
    case 0:b=4;break;
    case 1:b=1;break;
    case 2:b=3;break;
    case 4:b=2;break;
    default:b=-1;break;
    }
    button_result=-1; 
    return b;//Return button
}


void button_delay(int a,int b)
{
  int c ;
  if (a==0 || b==0)
  return;
  
  while (a--)
  for (c=0;c  ;
}

void share_eint(int b)//Because the interrupt processing flow is the same, we share a processing function, int b is to select which external interrupt source is
{ 
  if ( (rEXTINT0>>(4*b)&7)==0x1 )//Judge whether it is a high-level interrupt
  {
  button_result=b;//Notify that a key is pressed
  rEXTINT0 &=~( (7<<16)|(7<<8)|(7<<4)|(7) );//Set the four buttons to low level to enter the interrupt
  rINTMSK &= ~((U32)0x17);//Enable interrupt eint 0,1,2
  rEINTMASK &= ~((U32)0x10);//Enable interrupt eint 4 
  }
  else
  {
  button_delay(100,100);//Delay debounce
  rGPFCON &=~( (3<<8)|0x3f );//Set the pin to inputif
  ( !(rGPFDAT&(1<  {//It is at a low level, confirm that a key is pressedif
       (b<4)//If 0,1,2 interrupt
       {
       rINTMSK |= ((U32)0x17)&(~(1<       rEINTMASK |= (U32)0x10;//Shield interrupt eint 4
       rEXTINT0 |=(1<<4*b); //Set to high level interrupt
       }
       else//If it is 4 interrupts
       {
      //Uart_Printf("int 4/r/n");
       rINTMSK |= ((U32)0x17)&(~(1<       rEINTMASK &= ~((U32)0x10);//Enable interrupt eint 4   
       rEXTINT0 |=(1<<4*b); //Set to high level interrupt
      }
    
  }
  else
  {
  //It is jitter, do nothing
  }
  }
  
  rGPFCON &=~( (3<<8)|0x3f );//Set GPIO to external interrupt mode
  rGPFCON |= ( (2<<8)|0x2a );
 
  rSRCPND |= 0x17;//clear interrupt flag
  rINTPND |= 0x17;
  rEINTPEND |= 0x10;

}

void __irq eint0ISR(void) //eint0 interrupt function
{ 
  share_eint(0);
}

void __irq eint1ISR(void) //eint1 interrupt function
{
  share_eint(1);
}

void __irq eint2ISR(void) //eint2 interrupt function
{
  share_eint(2);
}

void __irq eint4_7ISR(void) //eint4 interrupt function
{ 
  if (rEINTPEND&0x10)
  share_eint(4);
  
  rSRCPND |= 0x17;//clear interrupt flag
  rINTPND |= 0x17;
  rEINTPEND |= 0x10;
}

void init_eint_button(void)//initialization
{ 
  button_result=-1;//No key pressed
  //Set interrupt entry
   pISR_EINT0=(U32)eint0ISR;
   pISR_EINT1=(U32)eint1ISR;
   pISR_EINT2=(U32)eint2ISR;
   pISR_EINT4_7=(U32)eint4_7ISR;//eint4~7 share an interrupt
  
  rINTMOD &= ~((U32)0x17);//Use IRQ mode
  
  rGPFUP |= 0x17;//No pull-up resistor
  rGPFCON &=~( (3<<8)|0x3f );//Set GPIO
  rGPFCON |= ( (2<<8)|0x2a );
  rEXTINT0 &=~( (7<<16)|(7<<8)|(7<<4)|(7) );//All four buttons enter the interrupt at low level
  
  //Open interrupt
  rSRCPND |= 0x17;//Clear interrupt flag
  rINTPND |= 0x17;
  rEINTPEND |= 0x10;
  
  rINTMSK &= ~((U32)0x17);//Enable interrupt eint 0,1,2
  rEINTMASK &= ~((U32)0x10);//Enable interrupt eint 4
 // Uart_Printf("button init/n/r");
}

Achievement results: