/*
* 本文中的相关图片来自火哥的教程，只作为随笔记录，无侵权之意
* 21:25:46, 2017-04-08
*/
EXTI：外部中断/事件控制器。STM32F429共有23根，其中EXTI0~EXTI15，分别对应GPIO中的PX0 ~ PX15，另外7根线有如下用途：
（中间省略了EXTI1 ~ EXTI15）
EXTI功能框图如下所示：
按照图中的序号标识，可以清晰的看出外部GPIO引脚上的电平变化是如何传递到内核，即GPIO -> EXTI -> NVIC，并触发相应的中断/事件。NVIC属于内核上的外设，EXTI和GPIO同属于STM32F4XX的片上外设。
举例：按键触发中断控制LED亮灭
分析：分别从GPIO, EXTI以及NVIC和最后的ISR部分，来构建整个程序的功能
如果我们需要使用EXTI和GPIO这两个外设，第一步就需要中RCC（Reset & Clock Control）相关寄存器中使能（ENABLE）相应的时钟，因此需要分别使能实际用到的GPIOA-I中的一个或多个端口时钟；使能EXTI时钟
RCC_AHB1PeriphClockCmd (KEY2_GPIO_CLK, ENABLE); RCC_APB2PeriphClockCmd (RCC_APB2Periph_SYSCFG, ENABLE);
接下来需要配置GPIO的引脚各寄存器，比如输入输出，上下拉等，之后可以调用固件库函数GPIO_Init(Init_Struct)进行初始化。
现在，引脚的相关工作模式已经配置好，如何把PIN与EXTI进行关联？STM32F4有如下说明：
即通过配置寄存器SYSCFG_EXTICRx，可以实现GPIO与EXTI的映射，参考stm32f4xx_syscfg.c Example：
SYSCFG_EXTILineConfig(KEY1_INT_EXTI_PORTSOURCE, KEY1_INT_EXTI_PINSOURCE);
接下来就是需要初始化EXTI相关的寄存器，同样最后也是调用EXTI_Init函数对EXTI寄存器进行初始化。
1 // EXTI_DeInit(); 2 EXTI_KEY1_InitStruct.EXTI_Line = EXTI_Line0; 3 EXTI_KEY1_InitStruct.EXTI_Trigger = EXTI_Trigger_Rising; 4 EXTI_KEY1_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt; 5 EXTI_KEY1_InitStruct.EXTI_LineCmd = ENABLE; 6 7 /*Initiallize the EXTI*/ 8 EXTI_Init(&EXTI_KEY1_InitStruct);
之后进行NVIC初始化，NVIC是嵌套向量中断控制器，掌管着包括内核异常（EXCEPTION）和外部中断（INTERRPUT）在内的相关功能。其中初始化部分，主要包括：确定中断源，确定抢占优先级，确定子优先级，是否使能NVIC_IRQChannel中指定的中断源。
@note To configure interrupts priority correctly, the NVIC_PriorityGroupConfig() function should be called before NVIC_Init() function.
1 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); 2 3 NVIC_InitStruct ->NVIC_IRQChannel = EXTI0_IRQn; 4 NVIC_InitStruct ->NVIC_IRQChannelPreemptionPriority = 1; 5 NVIC_InitStruct ->NVIC_IRQChannelSubPriority = 1; 6 NVIC_InitStruct ->NVIC_IRQChannelCmd = ENABLE; 7 8 /* 调用固件库NVIC初始化函数 - misc.c */ 9 NVIC_Init(NVIC_InitStruct);
最后需要装stm32f4xx_it.c中编写相应的ISR
1 /**
2 * @brief This function handles EXTI0 Handler
3 * @param None
4 * @retval None
5 */
6 void EXTI0_IRQHandler(void){
7 if(EXTI_GetITStatus(EXTI_Line0) != RESET){
8 LED1_TOGGLE;
9 EXTI_ClearITPendingBit(EXTI_Line0);
10 }
11 }
附：bsp_exti.c
1 #include "bsp_exti.h"
2 #include "stm32f4xx.h"
3
4 /**
5 * Four Steps to Config A Key Related EXTI Interrupt
6 * S1: Initiallize the GPIOA, PA0
7 * S2:
8 * S3:
9 * S4:
10 *
11 */
12
13
14 /**
15 * @brief S1: Initiallize the KEY1: PA0.
16 * Initiallize the Key2: PC13
17 *
18 * @note .
19 *
20 * @note .
21 *
22 * @param NONE
23 * This parameter can be one of the following values:
24 * @arg
25 * @arg
26 *
27 * @retval None
28 */
29 void EXTI_KEY_Config(void){
30 EXTI_InitTypeDef EXTI_KEY1_InitStruct;
31 GPIO_InitTypeDef GPIO_InitStructure;
32
33 /*?a??KEY1, KEY2 ?à1?μ?GPIOíaéèê±?ó*/
34 RCC_AHB1PeriphClockCmd (KEY1_GPIO_CLK, ENABLE);
35 RCC_AHB1PeriphClockCmd (KEY2_GPIO_CLK, ENABLE);
36 RCC_APB2PeriphClockCmd (RCC_APB2Periph_SYSCFG, ENABLE);
37
38 /*S3: Initiallize NVIC for EXTI0*/
39 EXTI_NVIC_Config();
40
41 /*????òa????μ?GPIOòy??*/
42 GPIO_InitStructure.GPIO_Pin = KEY1_GPIO_PIN;
43 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
44 GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
45
46 /*μ÷ó??aoˉêy￡?ê1ó?é???????μ?GPIO_InitStructure3?ê??ˉGPIO*/
47 GPIO_Init(KEY1_GPIO_PORT, &GPIO_InitStructure);
48
49 /* Init PC13 for KEY2*/
50 GPIO_InitStructure.GPIO_Pin = KEY2_GPIO_PIN;
51 GPIO_Init(KEY2_GPIO_PORT, &GPIO_InitStructure);
52
53 /*
54 * Set the SYSCFG_EXTICR1: Connects PA0 with EXTI0
55 * Connects PC13 with EXTI13
56 */
57 SYSCFG_EXTILineConfig(KEY1_INT_EXTI_PORTSOURCE, KEY1_INT_EXTI_PINSOURCE);
58 SYSCFG_EXTILineConfig(KEY2_INT_EXTI_PORTSOURCE, KEY2_INT_EXTI_PINSOURCE);
59
60 /*S2: Initiallize the EXTI for KEY1 which connects to PA0*/
61
62 // EXTI_DeInit();
63 EXTI_KEY1_InitStruct.EXTI_Line = EXTI_Line0;
64 EXTI_KEY1_InitStruct.EXTI_Trigger = EXTI_Trigger_Rising;
65 EXTI_KEY1_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt;
66 EXTI_KEY1_InitStruct.EXTI_LineCmd = ENABLE;
67
68 /*Initiallize the EXTI*/
69 EXTI_Init(&EXTI_KEY1_InitStruct);
70
71 // EXTI_DeInit();
72 EXTI_KEY1_InitStruct.EXTI_Line = EXTI_Line13;
73 EXTI_KEY1_InitStruct.EXTI_Trigger = EXTI_Trigger_Falling;
74
75 EXTI_KEY1_InitStruct.EXTI_LineCmd = ENABLE;
76 EXTI_Init(&EXTI_KEY1_InitStruct);
77
78 }/*END --EXTI_KEY_Config--*/
79
80
81 /**
82 * @brief S3: Initiallize the NVIC in order to handle the interrupt
83 *
84 * @note .1 ê1?ü?D?????ó￡¨í¨3￡óéíaéè?à1???′??÷éè??￡?
85 * .2 ?????D??ó??è??·?×é￡¨NVIC_IPRX, SCB->AIRCR￡?
86 * .3 3?ê??ˉNVIC_InitTypeDef
87 * .4 ±àD′ISR
88 * @note .
89 *
90 * @param NONE
91 * This parameter can be one of the following values:
92 * @arg
93 * @arg
94 *
95 * @retval None
96 */
97 static void EXTI_NVIC_Config(void){
98
99 NVIC_InitTypeDef NVIC_INIT_S;
100 NVIC_InitTypeDef *NVIC_InitStruct = &NVIC_INIT_S;
101
102 /* .2 */
103 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
104
105 NVIC_InitStruct ->NVIC_IRQChannel = EXTI0_IRQn;
106 NVIC_InitStruct ->NVIC_IRQChannelPreemptionPriority = 1;
107 NVIC_InitStruct ->NVIC_IRQChannelSubPriority = 1;
108 NVIC_InitStruct ->NVIC_IRQChannelCmd = ENABLE;
109
110 /* .3 */
111 NVIC_Init(NVIC_InitStruct);
112
113 /*Following is for KEY2 PC13*/
114 NVIC_InitStruct ->NVIC_IRQChannel = EXTI15_10_IRQn;
115 NVIC_Init(NVIC_InitStruct);
116 }
117
118 /**
119 * @brief
120 *
121 * @note .
122 *
123 * @note .
124 *
125 * @param NONE
126 * This parameter can be one of the following values:
127 * @arg
128 * @arg
129 *
130 * @retval None
131 */
时间： 2024-10-23 12:58:59