Small knowledge, big challenge! This article is participating in the creation activity of “Essential Tips for Programmers”
This article has participated in the “Digitalstar Project” and won a creative gift package to challenge the creative incentive money.
Interrupt is one of the most important functions in the MCU, through interrupt can improve the operation efficiency of the program, can be the MCU timely response to various peripheral requests. The interrupt of STM32 series MCU is mainly managed by nested vector interrupt controller.
The nested vector interrupt controller has the following characteristics:
- 68 masked interrupt channels (excluding the 16 Cortex™-M3 interrupts);
- 16 programmable priority levels (using 4-bit interrupt priority);
- Low latency exception and interrupt handling;
- Power management control;
- The realization of system control register;
The nested vector interrupt Controller (NVIC) is closely linked to the processor core, enabling low latency interrupt processing and efficient processing of late interrupts.
The external interrupt/event controller consists of 19 edge detectors that generate event/interrupt requests. Each input line can be independently configured with the input type (pulse or suspend) and corresponding triggering events (rising or falling or both). Each input line can be screened independently. The suspend register holds the interrupt request for the state line.
The main characteristics of EXTI controller are as follows:
- Each interrupt/event has its own triggering and masking
- Each interrupt line has a dedicated status bit
- Supports interrupt/event requests for up to 20 software
- Detects external signals whose pulse width is lower than the APB2 clock width. Refer to the electrical characteristics section of the data sheet for related parameters.
Interrupt control block diagram is as follows:
The following key port as an interrupt detection port, to demonstrate the use of interrupt.
//KEY0 PC1 KEY1 PC13 WK_UP PA0
void KEY_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOC, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_13;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; // Pull up input
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD; // Drop input
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
Copy the codeThe IO port used by the key is initialized first. Three keys are used here. One of the keys is low by default, and becomes high after the key is pressed. The remaining two keys are high by default and low when pressed. Let’s start the initialization interrupt.
//KEY0 PC1 KEY1 PC13 WK_UP PA0
void EXTIx_Init(void)
{
EXTI_InitTypeDef EXTI_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
// 1. Initialize the IO
KEY_Init(); // Key port initialization
// 2. Start AFIO clock
RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE); // Enable the function clock reuse function
// 3. Set the mapping between the I/O port and the interrupt line
GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0); //PA0
// 4. Set trigger condition for initialization line interruption
EXTI_InitStructure.EXTI_Line = EXTI_Line0; / / WK_UP rise along
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOC, GPIO_PinSource1); //PC1
EXTI_InitStructure.EXTI_Line = EXTI_Line1; / / KEY0 drop down
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
GPIO_EXTILineConfig(GPIO_PortSourceGPIOC, GPIO_PinSource13);//PC13
EXTI_InitStructure.EXTI_Line = EXTI_Line13; / / KEY1 rise along
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
// 5. Configure interrupt group and enable interrupt
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x03;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x02;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x01;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
void EXTI0_IRQHandler(void)
{
if(EXTI_GetITStatus(EXTI_Line0) ! = RESET) { delay_ms(10);
if(WK_UP == 1) { LED0 = ! LED0; LED1 = ! LED1; } EXTI_ClearITPendingBit(EXTI_Line0); }}void EXTI1_IRQHandler(void)
{
if(EXTI_GetITStatus(EXTI_Line1) ! = RESET) { delay_ms(10);
if(KEY0 == 1)
{
LED0 = !LED0;
}
EXTI_ClearITPendingBit(EXTI_Line1);
}
}
void EXTI15_10_IRQHandler(void)
{
if(EXTI_GetITStatus(EXTI_Line13) ! = RESET) { delay_ms(10);
if(KEY1 == 1)
{
LED1 = !LED1;
}
EXTI_ClearITPendingBit(EXTI_Line13);
}
}
Copy the codeDuring initialization, you need to set the interrupt line corresponding to each I/O interface. The connection between the interrupt line is shown as follows:
It can be seen from the figure above that all ports P0 correspond to median line 0, all ports P1 correspond to median line 1, and so on. The three keys used here are PC1, PC13 and PA0, that is, the corresponding interrupt line is interrupt line 1, interrupt line 13 and interrupt line 0.
After the interrupt line is set, the interrupt group needs to be set, that is, the interrupt priority needs to be set. When the interrupt is triggered at the same time, the interrupt with higher priority will be processed first.
After the interrupt line is set, the interrupt entry function needs to be provided, because when the interrupt is triggered, the system will automatically jump to the interrupt entry function and execute the interrupt function code. The function name for each interrupt entry is fixed and cannot be defined by itself. The entry name of the interrupt function can be viewed in the startup_stm32f10x_hs.s file.
; External Interrupts
DCD WWDG_IRQHandler ; Window Watchdog
DCD PVD_IRQHandler ; PVD through EXTI Line detect
DCD TAMPER_IRQHandler ; Tamper
DCD RTC_IRQHandler ; RTC
DCD FLASH_IRQHandler ; Flash
DCD RCC_IRQHandler ; RCC
DCD EXTI0_IRQHandler ; EXTI Line 0
DCD EXTI1_IRQHandler ; EXTI Line 1
DCD EXTI2_IRQHandler ; EXTI Line 2
DCD EXTI3_IRQHandler ; EXTI Line 3
DCD EXTI4_IRQHandler ; EXTI Line 4
DCD DMA1_Channel1_IRQHandler ; DMA1 Channel 1
DCD DMA1_Channel2_IRQHandler ; DMA1 Channel 2
DCD DMA1_Channel3_IRQHandler ; DMA1 Channel 3
DCD DMA1_Channel4_IRQHandler ; DMA1 Channel 4
DCD DMA1_Channel5_IRQHandler ; DMA1 Channel 5
DCD DMA1_Channel6_IRQHandler ; DMA1 Channel 6
DCD DMA1_Channel7_IRQHandler ; DMA1 Channel 7
DCD ADC1_2_IRQHandler ; ADC1 & ADC2
DCD USB_HP_CAN1_TX_IRQHandler ; USB High Priority or CAN1 TX
DCD USB_LP_CAN1_RX0_IRQHandler ; USB Low Priority or CAN1 RX0
DCD CAN1_RX1_IRQHandler ; CAN1 RX1
DCD CAN1_SCE_IRQHandler ; CAN1 SCE
DCD EXTI9_5_IRQHandler ; EXTI Line 9.. 5
DCD TIM1_BRK_IRQHandler ; TIM1 Break
DCD TIM1_UP_IRQHandler ; TIM1 Update
DCD TIM1_TRG_COM_IRQHandler ; TIM1 Trigger and Commutation
DCD TIM1_CC_IRQHandler ; TIM1 Capture Compare
DCD TIM2_IRQHandler ; TIM2
DCD TIM3_IRQHandler ; TIM3
DCD TIM4_IRQHandler ; TIM4
DCD I2C1_EV_IRQHandler ; I2C1 Event
DCD I2C1_ER_IRQHandler ; I2C1 Error
DCD I2C2_EV_IRQHandler ; I2C2 Event
DCD I2C2_ER_IRQHandler ; I2C2 Error
DCD SPI1_IRQHandler ; SPI1
DCD SPI2_IRQHandler ; SPI2
DCD USART1_IRQHandler ; USART1
DCD USART2_IRQHandler ; USART2
DCD USART3_IRQHandler ; USART3
DCD EXTI15_10_IRQHandler ; EXTI Line 15.10.
DCD RTCAlarm_IRQHandler ; RTC Alarm through EXTI Line
DCD USBWakeUp_IRQHandler ; USB Wakeup from suspend
DCD TIM8_BRK_IRQHandler ; TIM8 Break
DCD TIM8_UP_IRQHandler ; TIM8 Update
DCD TIM8_TRG_COM_IRQHandler ; TIM8 Trigger and Commutation
DCD TIM8_CC_IRQHandler ; TIM8 Capture Compare
DCD ADC3_IRQHandler ; ADC3
DCD FSMC_IRQHandler ; FSMC
DCD SDIO_IRQHandler ; SDIO
DCD TIM5_IRQHandler ; TIM5
DCD SPI3_IRQHandler ; SPI3
DCD UART4_IRQHandler ; UART4
DCD UART5_IRQHandler ; UART5
DCD TIM6_IRQHandler ; TIM6
DCD TIM7_IRQHandler ; TIM7
DCD DMA2_Channel1_IRQHandler ; DMA2 Channel1
DCD DMA2_Channel2_IRQHandler ; DMA2 Channel2
DCD DMA2_Channel3_IRQHandler ; DMA2 Channel3
DCD DMA2_Channel4_5_IRQHandler ; DMA2 Channel4 & Channel5
Copy the codeThe interrupt vector table here lists all interrupt function entry names.
When the key is pressed, the program will jump to the interrupt function, in the interrupt function through the LED light to indicate the effect of different keys pressed.