simplify and fix serialport-arduino sample (#75)

* simplify and fix serialport-arduino sample

* add sdk version in global.json

samples/serialport-arduino/README.md

@@ -46,21 +46,10 @@ To setup such app from the scratch (assumes your folder name is `arduino-demo` a
 
 ```
 dotnet new console
-dotnet add package System.IO.Ports
+dotnet add package System.IO.Ports -v 4.6.0-preview.18571.3
 ```
 
-ensure you got following nuget.config:
-
-```xml
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-  <packageSources>
-    <add key="dotnet-core" value="https://dotnet.myget.org/F/dotnet-core/api/v3/index.json" />
-  </packageSources>
-</configuration>
-```
-
-add runtime identifier in the property group to make it easier to publish:
+add runtime identifier in the property group to make it easier to publish (you can also provide it during publishing: `dotnet publish -r linux-arm`):
 
 ```xml
 <RuntimeIdentifier>linux-arm</RuntimeIdentifier>
@@ -79,12 +68,6 @@ To run your app simply call it while in that directory
 ./arduino-demo /dev/ttyS0
 ```
 
-Note: this version might be out of date and not contain recent fixes - please see dogfooding instructions to test latest version of System.IO.Ports
-
-### To dogfood latest bits
-
-[See example csproj file](arduino-demo.csproj) and edit versions accordingly (currently contains latest as of writing this demo). It contains comments explaining how to edit it and find latest versions.
-
 ## Arduino example app
 
 The most interesting part of the code is `serial_on_line_read` and `SPIN_PIXEL_ONCE` macro.

samples/serialport-arduino/arduino-demo.csproj

@@ -6,22 +6,9 @@
     <RootNamespace>arduino_demo</RootNamespace>
     <!-- this can also be passed from the command line (i.e. dotnet publish -r linux-arm) -->
     <RuntimeIdentifier>linux-arm</RuntimeIdentifier>
-    <!--
-        To use the latest version of core-setup we can pass the version manually:
-        <RuntimeFrameworkVersion>4.6.0-preview.18559.1</RuntimeFrameworkVersion>
-        Latest versions of all packages used here can be found here
-           (RuntimeFrameworkVersion is related to Microsoft.NETCore.App package):
-            https://github.com/dotnet/versions/blob/master/build-info/dotnet/core-setup/master/Latest_Packages.txt
-
-        Currently this is not needed because we consume private corefx.
-        Once this gets public the following line and package reference to Microsoft.Private.CoreFx.NETCoreApp
-        can be removed.
-    -->
-    <PackageConflictPreferredPackages>Microsoft.Private.CoreFx.NETCoreApp;runtime.$(RuntimeIdentifier).Microsoft.Private.CoreFx.NETCoreApp;$(PackageConflictPreferredPackages)</PackageConflictPreferredPackages>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Private.CoreFx.NETCoreApp" Version="4.6.0-preview.18559.1" />
     <PackageReference Include="System.IO.Ports" Version="4.6.0-preview.18558.3" />
   </ItemGroup>
 

samples/serialport-arduino/global.json

+{
+  "sdk": {
+    "version": "3.0.100-*"
+  }
+}
\ No newline at end of file