add USB docs ( english version )

docs/en/module/usb.md

@@ -0,0 +1,85 @@
+# USB
+
+<img src="assets/img/product_pics/module/module_usb_01.png" width="30%" height="30%"> <img src="assets/img/product_pics/module/module_usb_02.png" width="30%" height="30%">
+
+***
+
+:memo:**[Description](#Description)**&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;:octocat:**[Example](#Example)**&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;:electric_plug:**[Schematic](#Schematic)**&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;🛒**[Purchase](https://www.aliexpress.com/store/product/M5Stack-New-USB-Module-USB-HOST-HID-with-MAX3421E-SPI-Interface-Output-5-Input-5-Compatible/3226069_32961627365.html?spm=2114.12010615.8148356.4.6c042548sAUbGi)**
+
+## Description
+
+<mark>USB模块</mark>是一款USB控制器，内置了USB芯片MAX3421E。堆叠了M5Core之后，通过通信速率可高达26MHz的SPI接口与M5Core连接，即可作USB外设又可作USB主机。
+
+## Feature
+
+-  高达26MHz的SPI接口
+-  8路GPIO输入输出
+-  内置锂电池接口
+
+## Including
+
+-  1x USB模块
+
+## Application
+
+-  USB键盘记录器
+-  M5Core读写U盘
+
+## Related Link
+
+- **[Offical Video](https://www.youtube.com/channel/UCozgFVglWYQXbvTmGyS739w)**
+
+- **[Forum](http://forum.m5stack.com/)**
+
+- **[Datasheet]** - [MAX3421E](https://www.sparkfun.com/datasheets/DevTools/Arduino/MAX3421E.pdf)
+
+## Example
+
+*以下仅为用法示意，并不完整。如果需要完整例程请点击[这里](https://github.com/m5stack/M5-ProductExampleCodes/tree/master/Module/USB/Arduino)。*
+
+烧录例程`usb_mouse.ino`，USB鼠标接入模块之后，按住左键并拖动鼠标描绘白色线条；按住右键，描述绿色线条；按下中间滚轮键，清屏。
+
+```arduino
+#include <M5Stack.h>
+#include <SPI.h>
+#include <Usb.h>
+#include <hiduniversal.h>
+#include <hidboot.h>
+#include <usbhub.h>
+#include "M5Mouse.h"
+
+// new objects
+USB Usb;
+USBHub  Hub(&Usb);
+HIDBoot<USB_HID_PROTOCOL_MOUSE> HidMouse(&Usb);
+MouseRptParser  Prs;
+
+// initialization
+M5.begin();
+Usb.Init();
+HidMouse.SetReportParser(0,(HIDReportParser*)&Prs);
+
+// handle event coming from usb device
+Usb.Task();
+if(Usb.getUsbTaskState() == USB_STATE_RUNNING)
+{
+  Mouse_Pointer(mou_px, mou_py);
+  mou_px = 0;
+  mou_py = 0;
+  /* left button pressed: draw white point */
+  if (mou_button == 1)
+    M5.Lcd.drawCircle(StaPotX, StaPotY, 1, WHITE);
+  /* right button pressed: draw green point */
+  if (mou_button == 2)
+    M5.Lcd.drawCircle(StaPotX, StaPotY, 1, GREEN);
+  /* middle button pressed: clear screen */
+  if (mou_button == 4)
+    M5.Lcd.fillScreen(BLACK);
+}
+```
+
+<img src="assets/img/product_pics/module/module_example/USB/example_module_usb_01.png">
+
+## Schematic
+
+<img src="assets/img/product_pics/module/usb_sch.png">

docs/en/unit/gps.md

@@ -22,14 +22,14 @@
 <!-- -  GROVE接口，支持[UiFlow](http://flow.m5stack.com)编程，[Arduino](http://www.arduino.cc)编程 -->
 -  With two Lego plugin holes on the Unit, it could be more easier to compatable with Lego mountings
 
-## 应用
+## Application
 
 - Vehicle location
 - Intelligent Law enforcement location
 
-## 相关链接
+## Related Link
 
-- **[Offical Video](https://i.youku.com/i/UNjE1ODA2MzE0OA==?spm=a2hzp.8253869.0.0)**
+- **[Offical Video](https://www.youtube.com/channel/UCozgFVglWYQXbvTmGyS739w)**
 
 - **[Forum](http://forum.m5stack.com/)**
 

docs/index.md

@@ -47,9 +47,7 @@
 
 **Expansion Modules**
 
-[![battery_01.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_battery_01.png)](en/module/battery)         [![proto_01.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_proto_01.png)](en/module/proto)         [![plus_1.png](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_plus_01.png)](en/module/plus)
-
-<!-- [![module_usb.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_usb_01.png)](en/module/usb) -->
+[![battery_01.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_battery_01.png)](en/module/battery)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[![proto_01.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_proto_01.png)](en/module/proto)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[![plus_1.png](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_plus_01.png)](en/module/plus)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[![module_usb.jpg](http://m5-docs.oss-cn-shenzhen.aliyuncs.com/assets/img/product_pics/homepage_picture/module/module_usb_01.png)](en/module/usb)
 
 <!-- |[BATTERY]()|[PROTO]()| -->