add pi readme

Author: lxw119

README.md

@@ -6,6 +6,37 @@
 
 You can download the `.dll` at [Release](https://github.com/elephantrobotics/Mycobot.csharp/releases)
 
+#Build on PI<br>
+##Environment<br>
+The **MonoDevelop** development tool is recommended<br>
+How to **install MonoDevelop**:**https://www.monodevelop.com/download/#fndtn-download-lin**<br>
+eg:1、Install:<br>
+		**sudo apt install apt-transport-https dirmngr**<br>
+		**sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF**<br>
+		**echo "deb https://download.mono-project.com/repo/ubuntu vs-bionic main" | sudo tee /etc/apt/sources.list.d/mono-official-vs.list**<br>
+		**sudo apt update**<br>
+		**sudo apt-get install monodevelop**<br>
+	2、Test:<br>
+		**Test whether the software is successful**, see the introduction here: **https://www.monodevelop.com/documentation/creating-a-simple-solution/**<br>
+
+##Build&Run<br>
+1、Create a **C# console** application;<br>
+2、**Copy** the code of the cloned file **program.cs**,then **paste** it into the program.cs of the new project;<br>
+3、Change the **serial port** id to **/dev/ttyAMA0**;<br>
+![pic](res/chang_port.png)<br>
+4、Change the compilation mode to **Release**;<br>
+![pic](res/compile_mode.png)<br>
+5、Add **Mycobot.csharp.dll** library:ReFerences-->Edit References-->.Net Assembly-->Browse(path for .dll)<br>
+![pic](res/add-dll.gif)<br>
+6、Run.<br>
+Note:Build&&Run,the whole operation process can be seen in the following GIF:<br>
+![pic](res/all1.gif)<br>
+![pic](res/all2.gif)<br>
+![pic](res/all3.gif)<br>
+
+
+#Build on Windows
+
 ###**notice:**<br>
 if you project **target frame** is **.net core**,download **net core/Mycobot.csharp.dll**,if is **.net framework**,download **net framework/Mycobot.csharp.dll**)