diff --git a/book/08：补充内容/01.md b/book/08：补充内容/01.md
index 4ed68cb..d6f5149 100644
--- a/book/08：补充内容/01.md
+++ b/book/08：补充内容/01.md
@@ -177,3 +177,144 @@ float resistance2Temperature(float R1) {
 # 2. I2C
 
 [I2C 温湿度传感器](https://www.bilibili.com/video/BV1QN411D7ak/?spm_id_from=333.788&vd_source=3c8e333d6657680a469ddf0238f01d6a)
+
+## 2.1. 设置
+
+1. 先新建一个工程，取名为 humidity；
+2. 设置调试模式为 Serial Wire；
+3. 打开串口2；
+4. 查看开发板19号外设，使用PB6/PB7；
+
+![image-20241015151124859](./img/image-20241015151124859.png)
+
+在引脚设置中点击PB6，看到使用的是I2C1；
+
+![image-20241015151052757](./img/image-20241015151052757.png)
+
+5. 在Connectivity中找到I2C1，设置I2C模式为 I2C；
+
+![image-20241015151355494](./img/image-20241015151355494.png)
+
+6. 在Project Manager中设置为每个外设使用独立的 c/.h 文件：
+
+![image-20241015151501806](./img/image-20241015151501806.png)
+
+7. 按照上个例子设置printf使用浮点；
+
+## 2.2. 编码
+
+inc目录建立一个新文件aht20.h
+
+```h
+#ifndef __DHT20_H__
+#define __DHT20_H__
+
+#include "i2c.h"
+
+// 初始化AHT20
+void AHT20_Init(void);
+
+// 获取温度和湿度
+void AHT20_Read();
+
+#endif
+```
+
+src 目录建立一个新文件 aht20.c
+
+```c
+#include <aht20.h>
+
+#define AHT20_ADDRESS 0x70
+
+/**
+ * 查看状态字是否校准
+ */
+void AHT20_Init(void) {
+	uint8_t read_buf = 0;
+	// 等待DHT20上电稳定
+	HAL_Delay(40);
+	HAL_I2C_Master_Receive(&hi2c1, AHT20_ADDRESS, &read_buf, 1, 10);
+	if ((read_buf & 0x08) != 0x08) {
+		// 状态字没有校准，发送出初始化命令
+		uint8_t send_buf[3] = { 0xBE, 0x08, 0x00 };
+		HAL_I2C_Master_Transmit_DMA(&hi2c1, AHT20_ADDRESS, send_buf, 3);
+		HAL_Delay(100);
+	}
+}
+
+/**
+ *
+ */
+void AHT20_Read(float *temp, float *hum) {
+	uint8_t sendBuffer[3] = { 0xAC, 0x33, 0x00 };
+	uint8_t readBuffer[6];
+	HAL_I2C_Master_Transmit(&hi2c1, AHT20_ADDRESS, sendBuffer, 3, HAL_MAX_DELAY);
+	HAL_Delay(75);
+	HAL_I2C_Master_Receive(& hi2c1, AHT20_ADDRESS, readBuffer, 6, HAL_MAX_DELAY);
+	if ((readBuffer[0] & 0x80) == 0x00) {
+		uint32_t data = 0;
+		data = ((uint32_t) readBuffer[3] >> 4) + ((uint32_t) readBuffer[2] << 4) + ((uint32_t) readBuffer[1] << 12);
+		*hum = data * 100.0f / (1 << 20);
+
+		data = (((uint32_t) readBuffer[3] & 0x0F) << 16) + (((uint32_t) readBuffer[4]) << 8) + (uint32_t) readBuffer[5];
+		*temp = data * 200.0f / (1 << 20) - 50;
+	}
+}
+```
+
+main.c 文件的 USER CODE BEGIN Includes 区域添加头文件：
+
+```c
+/* USER CODE BEGIN Includes */
+#include "aht20.h"
+#include <stdio.h>
+#include <string.h>
+/* USER CODE END Includes */
+```
+
+main函数的 USER CODE BEGIN 2 区域添加内容
+
+```c
+	/* USER CODE BEGIN 2 */
+	AHT20_Init();
+	float temp, hum;
+	char message[50];
+	/* USER CODE END 2 */
+```
+
+完善 main 函数的 while 循环：
+
+```c
+	while (1) {
+		AHT20_Read(&temp, &hum);
+		sprintf(message, "温度：%.1f 湿度：%.1f \n", temp, hum);
+		HAL_UART_Transmit(&huart2, (uint8_t*) message, strlen(message), 100);
+		HAL_Delay(2000);
+		/* USER CODE END WHILE */
+
+		/* USER CODE BEGIN 3 */
+	}
+```
+
+## 2.3. 代码分析
+
+### 2.3.1. I2C的地址
+
+在启动传输后,随后传输的I2C首字节包括7位的I2C设备地址 0x38和一个SDA方向位 x(读R:‘1’，写W:‘0’)。
+
+![image-20241015145204114](./img/image-20241015145204114.png)
+
+因此，如果是读：实际地址是 0x71；如果是写，实际地址是0x70；注意代码中关于I2C的读写命令；
+
+HAL_I2C_Master_Transmit和HAL_I2C_Master_Receive 的地址都使用0x70，HAL_I2C_Master_Transmit会自动设置最后一位是0（仍然是0x70）；HAL_I2C_Master_Receive会自动设置最后一位是1（就是0x71）
+
+### 温湿度数据的重组
+
+按照AHT20的说明（p8），返回六个字节的顺序：
+
+![image-20241015162601769](./img/image-20241015162601769.png)
+
+![image-20241015162613515](./img/image-20241015162613515.png)
+
+![alt text](img/aht20_data.drawio.png)
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