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@@ -951,7 +951,7 @@ mark {
     display: -webkit-flex;
     display: flex;
     flex-direction:column;
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+    z-index: 50;
     width: max-content;
 
 }
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+++ b/docs/zh_CN/unit/pahub.md
@@ -35,6 +35,21 @@
 
 <img src="assets/img/product_pics/unit/pahub/pahub_sch.png">
 
+
+参考原理图及TCA9548A数据手册可知，该Unit能够通过控制A0~A2引脚的电平组合，修改设备的I2C地址。
+
+在Unit的PCB板上预留了三个贴片电阻焊接位，分别
+
+<img src="assets\img\product_pics\unit\pahub\pahub_p5.jpg">
+
+引脚电平组合与其对应的I2C地址如下表所示。
+
+<img src="assets\img\product_pics\unit\pahub\pahub_p4.jpg">
+
+
+该 Unit 的 I2C 地址为0x77（可通过调整电阻进行更改）.
+
+
 ### 套件清单
 
 - 1x PaHUB Unit