分享一款嵌入式开源按键框架代码工程MultiButton

一、工程简介

　　MultiButton 是一个小巧简单易用的事件驱动型按键驱动模块。

　　Github地址：https://github.com/0x1abin/MultiButton

　　这个项目非常精简，只有两个文件：

　　（1）可无限扩展按键；

　　（2）按键事件的回调异步处理方式可以简化程序结构，去除冗余的按键处理硬编码，让按键业务逻辑更清晰。

　　通过此工程可以学习到以下知识点：

　　（1）按键各种类型事件；

　　（2）状态机的思想；

　　（3）单向链表语法。

　　工程支持如下的按键事件：

　　MultiButton 的按键状态及软件流程图：

二、工程代码分析

　　注：在使用源码工程时稍微修改了两个点，后续贴出修改后的完整代码，有需要查看修改的同学可以将源码工程下载后进行对比，修改的点如下：

　　（1）将按键时间的相关参数通过接口定义进行初始化；

　　（2）修改按键长按期间一直触发事件为真正的长按按键定时触发事件。

　　在头文件multi_button.h中包括：

　　（1）定义了按键时间相关参数；

　　（2）定义了按键的事件类型；

　　（3）定义按键链表结构体，这里使用了位域操作，解决字节的存储空间问题。

 1 #ifndef _MULTI_BUTTON_H_
 2 #define _MULTI_BUTTON_H_
 3
 4 #include <stdint.h>
 5 #include <string.h>
 6
 7 typedef struct ButtonPara {
 8   uint8_t ticks_interval;
 9   uint8_t debounce_ticks;
10   uint16_t short_ticks;
11   uint16_t long_ticks;
12 }ButtonPara;
13
14 typedef void (*BtnCallback)(void*);
15
16 typedef enum {
17   PRESS_DOWN = 0,
18   PRESS_UP,
19   PRESS_REPEAT,
20   SINGLE_CLICK,
21   DOUBLE_CLICK,
22   LONG_PRESS_START,
23   LONG_PRESS_HOLD,
24   number_of_event,
25   NONE_PRESS
26 }PressEvent;
27
28 typedef struct Button {
29   uint16_t ticks;
30   uint8_t  repeat : 4;
31   uint8_t  event : 4;
32   uint8_t  state : 3;
33   uint8_t  debounce_cnt : 3;
34   uint8_t  active_level : 1;
35   uint8_t  button_level : 1;
36   uint8_t  button_id;
37   uint8_t  (*hal_button_Level)(uint8_t button_id_);
38   BtnCallback  cb[number_of_event];
39   struct Button* next;
40 }Button;
41
42 #ifdef __cplusplus
43 extern "C" {
44 #endif
45 void button_para_init(struct ButtonPara para);
46 void button_init(struct Button* handle, uint8_t(*pin_level)(uint8_t), uint8_t active_level, uint8_t button_id);
47 void button_attach(struct Button* handle, PressEvent event, BtnCallback cb);
48 PressEvent get_button_event(struct Button* handle);
49 int  button_start(struct Button* handle);
50 void button_stop(struct Button* handle);
51 void button_ticks(void);
52
53 #ifdef __cplusplus
54 }
55 #endif
56
57 #endif

　　在源码文件multi_button.c中包括：

　　（1）对按键时间参数进行初始化；

　　（2）对按键对象结构体进行初始化，初始化成员包括按键句柄，绑定GPIO电平读取函数，设置有效触发电平；

　　（3）初始化按键完成之后，进行按键绑定操作，将绑定按键结构体成员，按键触发事件，按键回调函数；

　　（4）按键启动：也就是将按键加入链表当中，启动按键。这里选择的插入方式是头部插入法，在链表的头部插入按键节点，效率高，时间复杂度为O(1)；

　　（5）按键删除：将按键从当前链表中删除。使用到了二级指针删除一个按键元素。与链表中成员删除方法相同；

　　（6）按键滴答函数：每间隔Nms触发一次按键事件，驱动状态机运行；

　　（7）读取当前引脚的状态，获取按键当前属于哪种状态；

　　（8）按键处理核心函数，驱动状态机。

  1 #include "multi_button.h"
  2
  3 #define EVENT_CB(ev)   if(handle->cb[ev])handle->cb[ev]((void*)handle)
  4 #define PRESS_REPEAT_MAX_NUM  15 /*!< The maximum value of the repeat counter */
  5
  6 static struct ButtonPara buttonpara;
  7 //button handle list head.
  8 static struct Button* head_handle = NULL;
  9
 10 static void button_handler(struct Button* handle);
 11
 12
 13 void button_para_init(struct ButtonPara para)
 14 {
 15   buttonpara.ticks_interval = para.ticks_interval;
 16   buttonpara.debounce_ticks = para.debounce_ticks;
 17   buttonpara.short_ticks = para.short_ticks;
 18   buttonpara.long_ticks = para.long_ticks;
 19 }
 20 /**
 21   * @brief  Initializes the button struct handle.
 22   * @param  handle: the button handle struct.
 23   * @param  pin_level: read the HAL GPIO of the connected button level.
 24   * @param  active_level: pressed GPIO level.
 25   * @param  button_id: the button id.
 26   * @retval None
 27   */
 28 void button_init(struct Button* handle, uint8_t(*pin_level)(uint8_t), uint8_t active_level, uint8_t button_id)
 29 {
 30   memset(handle, 0, sizeof(struct Button));
 31   handle->event = (uint8_t)NONE_PRESS;
 32   handle->hal_button_Level = pin_level;
 33   handle->button_level = handle->hal_button_Level(button_id);
 34   handle->active_level = active_level;
 35   handle->button_id = button_id;
 36 }
 37
 38 /**
 39   * @brief  Attach the button event callback function.
 40   * @param  handle: the button handle struct.
 41   * @param  event: trigger event type.
 42   * @param  cb: callback function.
 43   * @retval None
 44   */
 45 void button_attach(struct Button* handle, PressEvent event, BtnCallback cb)
 46 {
 47   handle->cb[event] = cb;
 48 }
 49
 50 /**
 51   * @brief  Inquire the button event happen.
 52   * @param  handle: the button handle struct.
 53   * @retval button event.
 54   */
 55 PressEvent get_button_event(struct Button* handle)
 56 {
 57   return (PressEvent)(handle->event);
 58 }
 59
 60 /**
 61   * @brief  Button driver core function, driver state machine.
 62   * @param  handle: the button handle struct.
 63   * @retval None
 64   */
 65 static void button_handler(struct Button* handle)
 66 {
 67   uint8_t read_gpio_level = handle->hal_button_Level(handle->button_id);
 68
 69   //ticks counter working..
 70   if((handle->state) > 0) handle->ticks++;
 71
 72   /*------------button debounce handle---------------*/
 73   if(read_gpio_level != handle->button_level) { //not equal to prev one
 74     //continue read 3 times same new level change
 75     if(++(handle->debounce_cnt) >= buttonpara.debounce_ticks) {
 76       handle->button_level = read_gpio_level;
 77       handle->debounce_cnt = 0;
 78     }
 79   } else { //level not change ,counter reset.
 80     handle->debounce_cnt = 0;
 81   }
 82
 83   /*-----------------State machine-------------------*/
 84   switch (handle->state) {
 85   case 0:
 86     if(handle->button_level == handle->active_level) {  //start press down
 87       handle->event = (uint8_t)PRESS_DOWN;
 88       EVENT_CB(PRESS_DOWN);
 89       handle->ticks = 0;
 90       handle->repeat = 1;
 91       handle->state = 1;
 92     } else {
 93       handle->event = (uint8_t)NONE_PRESS;
 94     }
 95     break;
 96
 97   case 1:
 98     if(handle->button_level != handle->active_level) { //released press up
 99       handle->event = (uint8_t)PRESS_UP;
100       EVENT_CB(PRESS_UP);
101       handle->ticks = 0;
102       handle->state = 2;
103     } else if(handle->ticks > buttonpara.long_ticks) {
104       handle->event = (uint8_t)LONG_PRESS_START;
105       EVENT_CB(LONG_PRESS_START);
106       handle->state = 5;
107     }
108     break;
109
110   case 2:
111     if(handle->button_level == handle->active_level) { //press down again
112       handle->event = (uint8_t)PRESS_DOWN;
113       EVENT_CB(PRESS_DOWN);
114       if(handle->repeat != PRESS_REPEAT_MAX_NUM) {
115         handle->repeat++;
116       }
117       EVENT_CB(PRESS_REPEAT); // repeat hit
118       handle->ticks = 0;
119       handle->state = 3;
120     } else if(handle->ticks > buttonpara.short_ticks) { //released timeout
121       if(handle->repeat == 1) {
122         handle->event = (uint8_t)SINGLE_CLICK;
123         EVENT_CB(SINGLE_CLICK);
124       } else if(handle->repeat == 2) {
125         handle->event = (uint8_t)DOUBLE_CLICK;
126         EVENT_CB(DOUBLE_CLICK); // repeat hit
127       }
128       handle->state = 0;
129     }
130     break;
131
132   case 3:
133     if(handle->button_level != handle->active_level) { //released press up
134       handle->event = (uint8_t)PRESS_UP;
135       EVENT_CB(PRESS_UP);
136       if(handle->ticks < buttonpara.short_ticks) {
137         handle->ticks = 0;
138         handle->state = 2; //repeat press
139       } else {
140         handle->state = 0;
141       }
142     } else if(handle->ticks > buttonpara.short_ticks) { // SHORT_TICKS < press down hold time < LONG_TICKS
143       handle->state = 1;
144     }
145     break;
146
147   case 5:
148     if(handle->button_level == handle->active_level) {
149       //continue hold trigger
150       if(handle->ticks > buttonpara.long_ticks) {
151       handle->event = (uint8_t)LONG_PRESS_HOLD;
152       EVENT_CB(LONG_PRESS_HOLD);
153       handle->ticks = 0;
154       }
155     } else { //released
156       handle->event = (uint8_t)PRESS_UP;
157       EVENT_CB(PRESS_UP);
158       handle->state = 0; //reset
159     }
160     break;
161   default:
162     handle->state = 0; //reset
163     break;
164   }
165 }
166
167 /**
168   * @brief  Start the button work, add the handle into work list.
169   * @param  handle: target handle struct.
170   * @retval 0: succeed. -1: already exist.
171   */
172 int button_start(struct Button* handle)
173 {
174   struct Button* target = head_handle;
175   while(target) {
176     if(target == handle) return -1;  //already exist.
177     target = target->next;
178   }
179   handle->next = head_handle;
180   head_handle = handle;
181   return 0;
182 }
183
184 /**
185   * @brief  Stop the button work, remove the handle off work list.
186   * @param  handle: target handle struct.
187   * @retval None
188   */
189 void button_stop(struct Button* handle)
190 {
191   struct Button** curr;
192   for(curr = &head_handle; *curr; ) {
193     struct Button* entry = *curr;
194     if(entry == handle) {
195       *curr = entry->next;
196 //      free(entry);
197       return;//glacier add 2021-8-18
198     } else {
199       curr = &entry->next;
200     }
201   }
202 }
203
204 /**
205   * @brief  background ticks, timer repeat invoking interval 5ms.
206   * @param  None.
207   * @retval None
208   */
209 void button_ticks(void)
210 {
211   struct Button* target;
212   for(target=head_handle; target; target=target->next) {
213     button_handler(target);
214   }
215 }

三、工程代码应用

　　以在freertos中应用为例，包括：

　　（1）按键对象的定义及时间参数定义；

　　（2）按键回调函数包括读取按键电平函数和各按键事件处理函数的编写；

　　（3）按键初始化操作及启动按键功能；

　　（4）在while(1)中添加按键滴答函数。

  1 #define TICKS_INTERVAL    5  //按键状态轮询周期，单位ms
  2 #define DEBOUNCE_TICKS    3  //MAX 7 (0 ~ 7) 去抖时间次数，此为15ms/TICKS_INTERVAL=3次
  3 #define SHORT_TICKS       (300 /TICKS_INTERVAL) //短按时间次数，300ms/TICKS_INTERVAL
  4 #define LONG_TICKS        (2000 /TICKS_INTERVAL) //长按时间次数，2000ms/TICKS_INTERVAL
  5
  6 enum Button_IDs {
  7   btn1_id,
  8   btn2_id,
  9   btn3_id,
 10 };
 11 struct ButtonPara btnpara = {TICKS_INTERVAL, DEBOUNCE_TICKS, SHORT_TICKS, LONG_TICKS};
 12 struct Button btn1;
 13 struct Button btn2;
 14 struct Button btn3;
 15
 16 //According to your need to modify the constants.
 17
 18 uint8_t read_button_GPIO(uint8_t button_id)
 19 {
 20   // you can share the GPIO read function with multiple Buttons
 21   switch(button_id)
 22   {
 23     case btn1_id:
 24       return GPIO_ReadInputDataBit(GPIOE,GPIO_Pin_4);
 25     case btn2_id:
 26       return GPIO_ReadInputDataBit(GPIOE,GPIO_Pin_3);
 27     case btn3_id:
 28       return GPIO_ReadInputDataBit(GPIOE,GPIO_Pin_2);
 29     default:
 30       return 0;
 31   }
 32 }
 33
 34 void BTN1_PRESS_DOWN_Handler(void* btn)
 35 {
 36   printf("BTN1_PRESS_DOWN_Handler!\r\n");
 37 }
 38
 39 void BTN1_PRESS_UP_Handler(void* btn)
 40 {
 41   printf("BTN1_PRESS_UP_Handler!\r\n");
 42 }
 43
 44 void BTN1_PRESS_REPEAT_Handler(void* btn)
 45 {
 46   printf("BTN1_PRESS_REPEAT_Handler, repeatcount = %d!\r\n",btn1.repeat);
 47 }
 48
 49 void BTN1_SINGLE_Click_Handler(void* btn)
 50 {
 51   printf("BTN1_SINGLE_Click_Handler!\r\n");
 52 }
 53
 54 void BTN1_DOUBLE_Click_Handler(void* btn)
 55 {
 56   printf("BTN1_DOUBLE_Click_Handler!\r\n");
 57 }
 58
 59 void BTN1_LONG_PRESS_START_Handler(void* btn)
 60 {
 61   printf("BTN1_LONG_PRESS_START_Handler!\r\n");
 62 }
 63
 64 void BTN1_LONG_PRESS_HOLD_Handler(void* btn)
 65 {
 66   printf("BTN1_LONG_PRESS_HOLD_Handler!\r\n");
 67 }
 68
 69 void BTN2_SINGLE_Click_Handler(void* btn)
 70 {
 71   printf("BTN2_SINGLE_Click_Handler!\r\n");
 72 }
 73
 74 void BTN2_DOUBLE_Click_Handler(void* btn)
 75 {
 76   printf("BTN2_DOUBLE_Click_Handler!\r\n");
 77 }
 78
 79 void BTN3_LONG_PRESS_START_Handler(void* btn)
 80 {
 81   printf("BTN3_LONG_PRESS_START_Handler!\r\n");
 82 }
 83
 84 void BTN3_LONG_PRESS_HOLD_Handler(void* btn)
 85 {
 86   printf("BTN3_LONG_PRESS_HOLD_Handler!\r\n");
 87 }
 88
 89 int main(void)
 90 {
 91   button_para_init(btnpara);
 92   button_init(&btn1, read_button_GPIO, 0, btn1_id);
 93   button_init(&btn2, read_button_GPIO, 0, btn2_id);
 94   button_init(&btn3, read_button_GPIO, 0, btn3_id);
 95
 96   button_attach(&btn1, PRESS_DOWN,       BTN1_PRESS_DOWN_Handler);
 97   button_attach(&btn1, PRESS_UP,         BTN1_PRESS_UP_Handler);
 98   button_attach(&btn1, PRESS_REPEAT,     BTN1_PRESS_REPEAT_Handler);
 99   button_attach(&btn1, SINGLE_CLICK,     BTN1_SINGLE_Click_Handler);
100   button_attach(&btn1, DOUBLE_CLICK,     BTN1_DOUBLE_Click_Handler);
101   button_attach(&btn1, LONG_PRESS_START, BTN1_LONG_PRESS_START_Handler);
102   button_attach(&btn1, LONG_PRESS_HOLD,  BTN1_LONG_PRESS_HOLD_Handler);
103
104   button_attach(&btn2, PRESS_REPEAT,     BTN2_PRESS_REPEAT_Handler);
105   button_attach(&btn2, SINGLE_CLICK,     BTN2_SINGLE_Click_Handler);
106   button_attach(&btn2, DOUBLE_CLICK,     BTN2_DOUBLE_Click_Handler);
107
108   button_attach(&btn3, LONG_PRESS_START, BTN3_LONG_PRESS_START_Handler);
109   button_attach(&btn3, LONG_PRESS_HOLD,  BTN3_LONG_PRESS_HOLD_Handler);
110
111   button_start(&btn1);
112   button_start(&btn2);
113   button_start(&btn3);
114
115
116   xTaskCreate((TaskFunction_t )key_task,
117                 (const char*    )"key_task",
118                 (uint16_t       )KEY_STK_SIZE,
119                 (void*          )NULL,
120                 (UBaseType_t    )KEY_TASK_PRIO,
121                 (TaskHandle_t*  )&KeyTask_Handler);
122     vTaskStartScheduler();
123 }
124
125
126 void key_task(void *pvParameters)
127 {
128   while(1)
129   {
130     button_ticks();
131     vTaskDelay(5);      //5ms周期轮询
132   }
133 }

四、思考

　　使用中有如下问题值得思考：

　　（1）组合键和矩阵按键如何实现？

　　在函数uint8_t read_button_GPIO(uint8_t button_id)中进行组合键和矩阵按键返回值的自定义。

　　（2）多个按键时，按键参数进行区分？

　　去抖时间，短按时间，长按时间可以放在一个数组中区分，各个按键定义各自的参数。

　　（3）现在按键事件较多的情况时，需要多个绑定的事件函数？

　　可以将按键事件函数统一放在一个数组中进行初始化注册。

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