Winsoft has a native pascal component for Delphi XE5 Firemonkey on Android which will allow you to communicate with the ComPort of your Android device. Apparently not all phones have a ComPort but HTC devices do. There is a native library for Android in Java that will allow you to access the ComPort too but this component does not appear to use that library and is in pascal. This is a commercial com port component but it comes with a free trial so you can see if it works for you first. The example that is included with the free trial is pretty straight forward. Here is some sample code to read and write data to the ComPort:
procedure TFormMain.MemoKeyDown(Sender: TObject; var Key: Word; var KeyChar: Char; Shift: TShiftState);
procedure TFormMain.TimerTimer(Sender: TObject);
var Text: string;
Text := AComPort.ReadUtf8;
if Text <> '' then
Memo.Text := Memo.Text + Text;
Access The Com Port On Android With Delphi XE5 Firemonkey Component by Delphi XE5 XE6 XE7 XE8 10 Seattle Berlin Tokyo Firemonkey, Delphi Android, Delphi IOS is licensed under a Creative Commons Attribution 4.0 International License.