diff --git a/Core/Inc/bubble.h b/Core/Inc/bubble.h
new file mode 100644
index 0000000..3985546
--- /dev/null
+++ b/Core/Inc/bubble.h
@@ -0,0 +1,22 @@
+#ifndef __BUBBLE_H
+#define __BUBBLE_H
+
+
+#ifdef __cplusplus  
+extern "C" {    
+#endif
+
+#include "main.h"
+#include "stdint.h"
+
+extern uint8_t getPWMDutyCycle(void);
+uint8_t bubble_init(void);
+uint8_t bubble_set_mode(uint8_t mode);
+uint8_t bubbleGetSize(void);
+uint8_t bubbleGetStatus(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
\ No newline at end of file
diff --git a/Core/Src/bubble.c b/Core/Src/bubble.c
new file mode 100644
index 0000000..28b9bf2
--- /dev/null
+++ b/Core/Src/bubble.c
@@ -0,0 +1,74 @@
+// Interface Mode 6 / 7
+// The output is configured as PWM output, the input is configured as test input.
+/*
++----------------------------+----------+--------------------------------------------+
+|            mode            | Priority |                  ABD-OUT                   |
++----------------------------+----------+--------------------------------------------+
+| Liquid/small-bubbles       | Low      | PWM-signal:20-<80%,represents-bubble-size  |
++----------------------------+----------+--------------------------------------------+
+| Air/Bubble                 | Medium   | 80%                                        |
++----------------------------+----------+--------------------------------------------+
+| Internal-error(self-test)  | High     | 90%                                        |
++----------------------------+----------+--------------------------------------------+
+| Serious-fault(watchdog)    | Highest  | Static-H                                   |
++----------------------------+----------+--------------------------------------------+
+| Start-Mode                 | --       | H                                          |
++----------------------------+----------+--------------------------------------------+
+| Boot-mode                  | --       | UART-Tx                                    |
++----------------------------+----------+--------------------------------------------+
+*/
+
+#include "bubble.h"
+#define DELTA 1
+/**
+ * 初始化
+ * 
+ * @return 0:成功 其他:失败 
+ */
+uint8_t bubble_init(void)
+{
+    return 0;
+}
+
+/**
+ * 设置模式
+ * 
+ * @param mode 模式
+ * @return 0:成功 其他:失败 
+ */
+uint8_t bubble_set_mode(uint8_t mode)
+{
+    return 0;
+}
+
+/**
+ * 获取气泡大小
+ * 
+ * @return 气泡大小,20-80%/小气泡，80-90%/大气泡，90%以上/故障
+ */
+uint8_t bubbleGetSize(void)
+{
+    return getPWMDutyCycle();
+}
+
+/**
+ * 获取气泡状态
+ * 
+ * @return 气泡状态,0:无气泡,1:有气泡,2:故障
+ */
+uint8_t bubbleGetStatus(void)
+{
+    uint8_t size = bubbleGetSize();
+    if (size < (80 - DELTA))
+    {
+        return 0;
+    }
+    else if (size >= (80 - DELTA) && size < (90 + DELTA))
+    {
+        return 1;
+    }
+    else if (size <= (90 + DELTA) && size >= (90 - DELTA))
+    {
+        return 2;
+    }
+}