Re: GNAT.Serial_Communications

[tonyg <tonythegair@gmail.com>]

On Apr 15, 2:58 pm, tonyg <tonytheg...@gmail.com> wrote:
> On Apr 14, 6:52 pm, Chris Moore <zmo...@ntlworld.com> wrote:
>
>
>
> > On 13/04/2011 22:12, tonyg wrote:
>
> > > Its actually blocking on top of the write. Also I've discovered after
> > > much experimentation that the writes are not doing the job when it
> > > does not block up. Usually it blocks up after 3-4 write attempts. I
> > > expect I need to discover what is happening at the other end of the
> > > wire, but its my first experience of using a serial port for anything.
>
> > > I suspect there is an option I am not engaging in the setting up of
> > > the port. I am using the gpl version so I was thinking there could be
> > > a bug that is not in the gnat pro version, but I don't want to be a
> > > bad craftsman :) and gnat are usually pretty much on top of stuff like
> > > that from previous experience, but then again its a relatively new
> > > addition to the gnat compiler and no ones perfect. But.... its usually
> > > me.....
>
> > I suspect it's the speed setting.  Serial ports default to 9600 baud
> > which is slow so you're filling the buffers up with the first few writes
> > as they're unable to get the data out quick enough and then they start
> > to block cos there's nowhere to put the data.
>
> > > Saying that though I am successfully reading from the port the
> > > incoming messages although they do appear in sections and I have to
> > > keep re reading the port to get the full message...
>
> > This is how serial interfaces usually work.  The lowest level read
> > function returns the number of bytes actually read.
>
> I found the problem. Its very embarassing and completely my own fault!
> Basically I did not have the write access to the usb port! I am using
> ubuntu for this. Just to let those who are interested know.

Actually this is not the problem I spoke too soon. Minicom will talk
and read the correct values.
However gnat will read correctly but not write to the port properly,
but its not hanging anymore so thats a plus. I just cannot see why
minicom would write the string correctly to the port but when I write
the string to the port through gnat.serial_communication it does not
work!!

      GNAT.Serial_Communications.Write(Port   => The_Port,
                        Buffer =>
String_To_Stream(Broadcast_Message));

  function String_To_Stream ( The_String : in String) return
Ada.Streams.Stream_Element_Array is

      Return_Value :
Ada.Streams.Stream_Element_Array(1..The_String'length);

   begin
      Put (" Start of Data out  :- ");
      for count in
1..Ada.Streams.Stream_Element_Offset(The_String'Length) loop
         Return_Value(count) :=
character'pos(The_String(Integer(count)));
         int_io.Put(Integer(Return_Value(count)));
      end loop;
      Put (" End of Data out ");
	Put_Line (The_String);

      Return Return_Value(1..The_String'Length);
   end String_To_Stream;

Is there anything you can see thats wrong there ?