title: FormatException Uint8List convert to string with dart
body: <p>I am trying to convert a Uint8List to a string using Dart (in a Flutter project).
  I am using the Flutter Android USB Serial plugin ( <a href="https://github.com/altera2015/usbserial" rel="nofollow noreferrer">https://github.com/altera2015/usbserial</a>)</p>
  
  <p>The data are coming from a usb device and are returned from the library as a Stream. </p>
  
  <p>If outputed as a string, it looks like:</p>
  
  <p>[255,0,0,0,255....]</p>
  
  <p>When I try:</p>
  
  <pre><code>String newTag = ascii.decode(asyncSnapshot.data);
  </code></pre>
  
  <p>I get the error :</p>
  
  <pre><code>FormatException:Invalid value in input: 255
  </code></pre>
  
  <p>I don't know how to solve this issue, my result should be :</p>
  
  <pre><code>"352206000079439"
  </code></pre>