LPC1114的中斷,由中斷控制模組NVIC控制。一共32箇中斷,每個中斷的優先順序可程式設計為 0~3 四種級別。級別越高對應的優先順序越低。因此,級別0 是最高的中斷優先順序。
設定中斷優先順序的函式,CMISIS已經寫好,並嵌入到了編譯器中,例如,我們用KEIL開發的話,設定中斷優先順序的函式位於core_cm0.h檔案當中,函式如下所示:
/** \brief Set Interrupt Priority The function sets the priority of an interrupt. \note The priority cannot be set for every core interrupt. \param [in] IRQn Interrupt number. \param [in] priority Priority to set. */ __STATIC_INLINE void NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority) { ) { SCB->SHP[_SHP_IDX(IRQn)] = (SCB->SHP[_SHP_IDX(IRQn)] & ~(0xFF << _BIT_SHIFT(IRQn))) | (((priority << ( - __NVIC_PRIO_BITS)) & 0xFF) << _BIT_SHIFT(IRQn)); } else { NVIC->IP[_IP_IDX(IRQn)] = (NVIC->IP[_IP_IDX(IRQn)] & ~(0xFF << _BIT_SHIFT(IRQn))) | (((priority << ( - __NVIC_PRIO_BITS)) & 0xFF) << _BIT_SHIFT(IRQn)); } }
從上面函式可以看出,該函式有兩個引數,IRQn是指你要設定的中斷向量,priority是中斷優先順序,優先順序可以是0 1 2 3四個數,0的優先順序最大,3的優先順序最小。假設你要設定GPIO1中斷的優先順序最高,那麼就是:
NVIC_SetPriority(EINT1_IRQn, 0);
這時,有人會問,”EINT1_IRQn”從哪裡來?答:這個可以在LPC11xx.h檔案當中找到,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;