LPC1114单片机的NVIC中断函数，有开中断、关中断、设置优先级、挂起等操作函数。这些函数位于core_cm0.h文件里面。比如开中断的函数如下：
/** \brief Enable External Interrupt
The function enables a device-specific interrupt in the NVIC interrupt controller.
\param [in] IRQn External interrupt number. Value cannot be negative.
*/
__STATIC_INLINE void NVIC_EnableIRQ(IRQn_Type IRQn)
{
NVIC->ISER[] = ( << ((uint32_t)(IRQn) & 0x1F));
}
/**/里面的注释告诉我们，这是一个中断函数，函数的功能是允许一个中断，也就是开中断的意思。
比如我们要开P1口的中断，可以这样使用这个函数：NVIC_EnableIRQ(EINT1_IRQn)；
该函数里面，NVIC_EnableIRQ是函数名，EINT1_IRQn是参数，表示P1口的中断，这个参数可以在头文件lpc11xx.h文件中找到。如下所示：
* ==========================================================================
* ---------- Interrupt Number Definition -----------------------------------
* ==========================================================================
*/
typedef enum IRQn
{
/****** Cortex-M0 Processor Exceptions Numbers ******************************/
Reset_IRQn = -, /*!< 1 Reset Vector, invoked on Power up and warm reset */
NonMaskableInt_IRQn = -, /*!< 2 Non maskable Interrupt, cannot be stopped or preempted */
HardFault_IRQn = -, /*!< 3 Hard Fault, all classes of Fault */
SVCall_IRQn = -, /*!< 11 System Service Call via SVC instruction */
PendSV_IRQn = -, /*!< 14 Pendable request for system service */
SysTick_IRQn = -, /*!< 15 System Tick Timer */
/****** LPC11Cxx or LPC11xx Specific Interrupt Numbers *************************/
WAKEUP0_IRQn = , /*!< All I/O pins can be used as wakeup source. */
WAKEUP1_IRQn = , /*!< There are 13 pins in total for LPC11xx */
WAKEUP2_IRQn = ,
WAKEUP3_IRQn = ,
WAKEUP4_IRQn = ,
WAKEUP5_IRQn = ,
WAKEUP6_IRQn = ,
WAKEUP7_IRQn = ,
WAKEUP8_IRQn = ,
WAKEUP9_IRQn = ,
WAKEUP10_IRQn = ,
WAKEUP11_IRQn = ,
WAKEUP12_IRQn = ,
CAN_IRQn = , /*!< CAN Interrupt */
SSP1_IRQn = , /*!< SSP1 Interrupt */
I2C_IRQn = , /*!< I2C Interrupt */
TIMER_16_0_IRQn = , /*!< 16-bit Timer0 Interrupt */
TIMER_16_1_IRQn = , /*!< 16-bit Timer1 Interrupt */
TIMER_32_0_IRQn = , /*!< 32-bit Timer0 Interrupt */
TIMER_32_1_IRQn = , /*!< 32-bit Timer1 Interrupt */
SSP0_IRQn = , /*!< SSP0 Interrupt */
UART_IRQn = , /*!< UART Interrupt */
Reserved0_IRQn = , /*!< Reserved Interrupt */
Reserved1_IRQn = ,
ADC_IRQn = , /*!< A/D Converter Interrupt */
WDT_IRQn = , /*!< Watchdog timer Interrupt */
BOD_IRQn = , /*!< Brown Out Detect(BOD) Interrupt */
FMC_IRQn = , /*!< Flash Memory Controller Interrupt */
EINT3_IRQn = , /*!< External Interrupt 3 Interrupt */
EINT2_IRQn = , /*!< External Interrupt 2 Interrupt */
EINT1_IRQn = , /*!< External Interrupt 1 Interrupt */
EINT0_IRQn = , /*!< External Interrupt 0 Interrupt */
} IRQn_Type;
可以看到，共有32种中断，在使用的时候，你要开什么中断，就用NVIC开中断函数把对应的中断打开。
开了中断以后，中断函数怎么写呢？
例如P1口的中断函数这样写：
void PIOINT1_IRQHandler()
{
// 进中断以后执行的代码
}
为什么P1口的中断函数名称是PIOINT1_IRQHandler，这个其实在startup_lpc11xx.s文件中已经定义好了：
; External Interrupts DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; + : Wakeup PIO0. DCD WAKEUP_IRQHandler ; +: Wakeup PIO0. DCD WAKEUP_IRQHandler ; +: Wakeup PIO0. DCD WAKEUP_IRQHandler ; +: Wakeup PIO1. DCD CAN_IRQHandler ; +: CAN DCD SSP1_IRQHandler ; +: SSP1 DCD I2C_IRQHandler ; +: I2C DCD TIMER16_0_IRQHandler ; +: -bit Counter-Timer DCD TIMER16_1_IRQHandler ; +: -bit Counter-Timer DCD TIMER32_0_IRQHandler ; +: -bit Counter-Timer DCD TIMER32_1_IRQHandler ; +: -bit Counter-Timer DCD SSP0_IRQHandler ; +: SSP0 DCD UART_IRQHandler ; +: UART DCD USB_IRQHandler ; +: USB IRQ DCD USB_FIQHandler ; +: USB FIQ DCD ADC_IRQHandler ; +: A/D Converter DCD WDT_IRQHandler ; +: Watchdog Timer DCD BOD_IRQHandler ; +: Brown Out Detect DCD FMC_IRQHandler ; +: IP2111 Flash Memory Controller DCD PIOINT3_IRQHandler ; +: PIO INT3 DCD PIOINT2_IRQHandler ; +: PIO INT2 DCD PIOINT1_IRQHandler ; +: PIO INT1 DCD PIOINT0_IRQHandler ; +: PIO INT0
总结：NVIC的函数使用，就是这么简单，KEIL已经给我们写好，我们直接使用即可！
