LPC2478 external interrupt usage

LPC2478 external interrupt

The external interrupt model of 2478 is as follows

That is to say, port 0 and 2 support external interrupts, EINT0-2 are interrupts for three independent pins, and EINT3 is the vector shared by all interrupts of port 0 and 2.

For port 0 and 2, you do not need to configure the pins to interrupt mode. Just configure them to input mode and enable interrupts. For independent interrupts, the configuration process is as follows

1. Configure the corresponding pin to EINT mode

2. Set the mode to pull up or down according to your needs

3. Configure the interrupt mode and interrupt polarity in the system control register

4. Configure the middle end, match the interrupt function, priority, enable interrupt, etc.

The interrupts of PORT0 and PORT2 are actually similar in usage, mainly the configuration of EINT3

1. Select GPIO for IO port function

2. Enable the GPIO interrupt of the pin

3. Next, configure the eint3 interrupt and you can use it

When interrupt processing, eint0-2 can be processed directly, and port0 and port2 interrupts in eint3 need to be judged once, relying on the following three registers

From these three registers, you can see the interrupt status of each pin and choose the correct processing method

Check the code for details

1. #ifndef __EXTI_H_  

2. #define __EXTI_H_  

3. #include "common.h"  

4. #include "lpc24xx.h"  

5.   

6. extern u8 eint0Count;  

7.   

8. extern u8 eint3Count;  

9.   

10. void ExtiInit(void);  

11.   

12.   

13. void GPIOEINT3Init(void);  

14.   

15.   

16. #endif  

1. #include "exti.h"  

2.   

3. u8 eint0Count = 0;  

4. u8 eint3Count = 0;  

5.   

6. void __irq EINT0_Handler(void)  

7. {  

8.     IENABLE; /* handles nested interrupt */    

9.     EXTINT |= (1<<0); // Clear interrupt  

10.     //do something here  

11.       

12.     eint0Count = 1;  

13.       

14.     IDISABLE;  

15.     VICVectAddr = 0; /* Acknowledge Interrupt */  

16. }  

17.   

18. void __irq EINT3_Handler(void)  

19. {  

20.     IENABLE; /* handles nested interrupt */    

21.     //do something here  

22.       

23.     if((IO_INT_STAT&(1<<0)) == 1)//port0 interrupt  

24.     {  

25.         if((IO0_INT_STAT_F&(1<<10)) != 0)//Confirm that an interrupt occurs on P0.10  

26.         {  

27.             eint3Count = 1;  

28.             IO0_INT_CLR |= (1<<10);  

29.         }  

30.     }  

31.     EXTINT |= (1<<3); // Clear interrupt  

32.       

33.     IDISABLE;  

34.     VICVectAddr = 0; /* Acknowledge Interrupt */  

35. }  

36.   

37.   

38.   

39.   

40. //Use exti0 as an example  

41. void ExtiInit(void)  

42. {  

43.     PINSEL4 &= ~(3<<20); //Configure as interrupt  

44.     PINSEL4 |= (1<<20);  

45.       

46.     PINMODE4 &= ~(3<<20); //Configure pull-up resistor  

47.       

48.     EXTMODE |= (1<<0); //Edge trigger  

49. //    

50.     EXTPOLAR |= (1<<0); // rising edge trigger  

51.       

52.     //Interrupt vector configuration  

53.     VICSoftIntClr |= (1<<14); // Clear software interrupt, eint0 interrupt source is 14 0 start  

54.     VICIntEnClr |= (1<<14); //Disable interrupt  

55.     VICIntSelect &= (1<<14); //Select IRQ interrupt  

56.     VICVectAddr14 = (unsigned)EINT0_Handler; //Connect interrupt vector  

57.     VICVectPriority14 = 0x01; //Interrupt priority register  

58.     VICIntEnable |= (1<<14); //Interrupt vector enable is valid  

59. }  

60.   

61.   

62.   

63. //Use p0.10 as an example  

64. void GPIOEINT3Init(void)  

65. {  

66.     PINSEL0 &= ~(3<<20); //Select normal IO function  

67.     PINMODE0 &= ~(3<<20); //Select pull-up  

68.     IO0_INT_EN_F |= (1<<10); // falling edge interrupt enable  

69.       

70.       

71.     EXTMODE |= (1<<3); //Edge trigger  

72.     EXTPOLAR &= ~(1<<3); //Falling edge trigger  

73.       

74.     //Interrupt vector configuration  

75.     VICSoftIntClr |= (1<<17); // Clear software interrupt, eint3 interrupt source is 17 0 start  

76.     VICIntEnClr |= (1<<17); //Disable interrupt  

77.     VICIntSelect &= (1<<17); //Select IRQ interrupt  

78.     VICVectAddr17 = (unsigned)EINT3_Handler; //Connect interrupt vector  

79.     VICVectPriority17 = 0x01; //Interrupt priority register  

80.     VICIntEnable |= (1<<17); //Interrupt vector enable is valid  

81.       

82. }  

In the external interrupt handler, remember to clear the corresponding IO port interrupt first

Then clear the EINT0 interrupt. Do not clear EINT first and then clear the IO port interrupt (this will cause repeated interrupts)