diff --git a/README.md b/README.md
index ea55082..c74d19b 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ struct Button button1;
 2.初始化按键对象，绑定按键的GPIO电平读取接口**read_button_pin()** ，后一个参数设置有效触发电平
 
 ```c
-button_init(&button1, read_button_pin, 0);
+button_init(&button1, read_button_pin, 0, 0);
 ```
 3.注册按键事件
 
@@ -52,7 +52,8 @@ struct Button {
 	uint8_t  debounce_cnt : 3;
 	uint8_t  active_level : 1;
 	uint8_t  button_level : 1;
-	uint8_t  (*hal_button_Level)(void);
+	uint8_t  button_id;
+	uint8_t  (*hal_button_Level)(uint8_t  button_id_);
 	BtnCallback  cb[number_of_event];
 	struct Button* next;
 };
@@ -78,11 +79,23 @@ LONG_PRESS_HOLD | 长按期间一直触发
 ```c
 #include "button.h"
 
+unit8_t btn1_id = 0;
+
 struct Button btn1;
 
-uint8_t read_button1_GPIO()
+uint8_t read_button_GPIO(uint8_t button_id)
 {
-	return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
+	// you can share the GPIO read function with multiple Buttons
+	switch(button_id)
+	{
+		case btn1_id:
+			return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
+			break;
+
+		default:
+			return 0;
+			break;
+	}
 }
 void BTN1_PRESS_DOWN_Handler(void* btn)
 {
@@ -98,7 +111,7 @@ void BTN1_PRESS_UP_Handler(void* btn)
 
 int main()
 {
-	button_init(&btn1, read_button1_GPIO, 0);
+	button_init(&btn1, read_button_GPIO, 0, btn1_id);
 	button_attach(&btn1, PRESS_DOWN,       BTN1_PRESS_DOWN_Handler);
 	button_attach(&btn1, PRESS_UP,         BTN1_PRESS_UP_Handler);
 	button_attach(&btn1, PRESS_REPEAT,     BTN1_PRESS_REPEAT_Handler);
diff --git a/examples/example_callback.c b/examples/example_callback.c
index d774069..2c9f267 100644
--- a/examples/example_callback.c
+++ b/examples/example_callback.c
@@ -1,22 +1,36 @@
 #include "multi_button.h"
 
+enum Button_IDs {
+	btn1_id,
+	btn2_id,
+};
+
 struct Button btn1;
 struct Button btn2;
 
-uint8_t read_button1_GPIO()
+uint8_t read_button_GPIO(uint8_t button_id)
 {
-	return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
-}
+	// you can share the GPIO read function with multiple Buttons
+	switch(button_id)
+	{
+		case btn1_id:
+			return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
+			break;
 
-uint8_t read_button2_GPIO()
-{
-	return HAL_GPIO_ReadPin(B2_GPIO_Port, B2_Pin);
+		case btn2_id:
+			return HAL_GPIO_ReadPin(B2_GPIO_Port, B2_Pin);
+			break;
+
+		default:
+			return 0;
+			break;
+	}
 }
 
 int main()
 {
-	button_init(&btn1, read_button1_GPIO, 0);
-	button_init(&btn2, read_button2_GPIO, 0);
+	button_init(&btn1, read_button_GPIO, 0, btn1_id);
+	button_init(&btn2, read_button_GPIO, 0, btn2_id);
 
 	button_attach(&btn1, PRESS_DOWN,       BTN1_PRESS_DOWN_Handler);
 	button_attach(&btn1, PRESS_UP,         BTN1_PRESS_UP_Handler);
@@ -54,5 +68,3 @@ void BTN1_PRESS_UP_Handler(void* btn)
 {
 	//do something...
 }
-
-...
\ No newline at end of file
diff --git a/examples/example_poll.c b/examples/example_poll.c
index 054cd72..162b357 100644
--- a/examples/example_poll.c
+++ b/examples/example_poll.c
@@ -1,10 +1,21 @@
 #include "multi_button.h"
 
+unit8_t btn1_id = 0;
 struct Button btn1;
 
-uint8_t read_button1_GPIO() 
+uint8_t read_button_GPIO(uint8_t button_id)
 {
-	return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
+	// you can share the GPIO read function with multiple Buttons
+	switch(button_id)
+	{
+		case btn1_id:
+			return HAL_GPIO_ReadPin(B1_GPIO_Port, B1_Pin);
+			break;
+
+		default:
+			return 0;
+			break;
+	}
 }
 
 
@@ -12,7 +23,7 @@ int main()
 {
 	static uint8_t btn1_event_val;
 	
-	button_init(&btn1, read_button1_GPIO, 0);
+	button_init(&btn1, read_button_GPIO, 0, btn1_id);
 	button_start(&btn1);
 	
 	//make the timer invoking the button_ticks() interval 5ms.
diff --git a/multi_button.c b/multi_button.c
index 762c797..878885d 100644
--- a/multi_button.c
+++ b/multi_button.c
@@ -15,15 +15,17 @@ static struct Button* head_handle = NULL;
   * @param  handle: the button handle strcut.
   * @param  pin_level: read the HAL GPIO of the connet button level.
   * @param  active_level: pressed GPIO level.
+  * @param  button_id: the button id.
   * @retval None
   */
-void button_init(struct Button* handle, uint8_t(*pin_level)(), uint8_t active_level)
+void button_init(struct Button* handle, uint8_t(*pin_level)(), uint8_t active_level, uint8_t button_id)
 {
 	memset(handle, 0, sizeof(struct Button));
 	handle->event = (uint8_t)NONE_PRESS;
 	handle->hal_button_Level = pin_level;
-	handle->button_level = handle->hal_button_Level();
+	handle->button_level = handle->hal_button_Level(button_id);
 	handle->active_level = active_level;
+	handle->button_id = button_id;
 }
 
 /**
@@ -55,7 +57,7 @@ PressEvent get_button_event(struct Button* handle)
   */
 void button_handler(struct Button* handle)
 {
-	uint8_t read_gpio_level = handle->hal_button_Level();
+	uint8_t read_gpio_level = handle->hal_button_Level(handle->button_id);
 
 	//ticks counter working..
 	if((handle->state) > 0) handle->ticks++;
diff --git a/multi_button.h b/multi_button.h
index 6cf54d7..b066ade 100644
--- a/multi_button.h
+++ b/multi_button.h
@@ -38,7 +38,8 @@ typedef struct Button {
 	uint8_t  debounce_cnt : 3;
 	uint8_t  active_level : 1;
 	uint8_t  button_level : 1;
-	uint8_t  (*hal_button_Level)(void);
+	uint8_t  button_id;
+	uint8_t  (*hal_button_Level)(uint8_t button_id_);
 	BtnCallback  cb[number_of_event];
 	struct Button* next;
 }Button;
@@ -47,7 +48,7 @@ typedef struct Button {
 extern "C" {
 #endif
 
-void button_init(struct Button* handle, uint8_t(*pin_level)(), uint8_t active_level);
+void button_init(struct Button* handle, uint8_t(*pin_level)(), uint8_t active_level, uint8_t button_id);
 void button_attach(struct Button* handle, PressEvent event, BtnCallback cb);
 PressEvent get_button_event(struct Button* handle);
 int  button_start(struct Button* handle);