bbc:microbit and buttons and No_Implicit_Dynamic_Code

["Björn Lundin" <b.f.lundin@gmail.com>]

Hi!
I got my microbot yesterday. I read about it here and
decided to try it out.

I also downloaded the cross-compiler and the gpl 2018 for linux
and ran it all on a linux virtualBox guest on a win 10 system.
I also cloned the Ada_Drivers_Library from github

To my surprise - it just worked :-)
And there was examples too.
I did try avr-ada with an Arduino Nano with limited success a couple of
years ago,but this was a very pleasant surprise.

So I tried some code of my own,
and there are 3 things I wonder.

1 - gpr and style. Why does the setting in the gpr file
   insist on a certain style, and treat everything else as error.
   Selecting all + tab does not pretty print in a way that the gpr file
   wants. Someone new to Ada would have a real hard time to get anything
   done. (Yes I did remove the gnaty but it should be so by default)

2 - Debugging. How do I do it? I've almost never used the debugger,
    not via GPS nor via GDB. Is there a guide somewhere how to use it
    via GPS? (Put_Lines have been my friend, thinking of taking
    advantage of the GPS)

3 - The microbit has 2 buttons. And the microbit.Button package has a
    way of subscribing callbacks to pressed/released events.
    But trying to use it I get

main.adb:55:33: violation of restriction "No_Implicit_Dynamic_Code" at
system.ads:45


code as below.

with Microbit.Display;
with Microbit.Buttons;
with Microbit.Time;

procedure Main is


use Microbit.Buttons;

  procedure Button_Pressed(Button : Button_Id;
                           State  : Button_State) is
  begin
    case State is
      when Pressed => Microbit.Display.Set(2,2);
      when Released => Microbit.Display.Clear(2,2);
    end case;
  end Button_Pressed;

  Ok : Boolean := True;
begin

  MicroBit.Display.Clear;
  Ok := Subscribe(Button_Pressed'Unrestricted_Access);
  if Ok then
    Microbit.Display.Set(0,0);
  end if;

  loop
    Microbit.Time.Delay_Ms (200);
  end loop;
end Main;


I did find an example using
      if State (Button_A) = Pressed then

so problem is fixed, but I like the callback style here.


Thanks for a good integration.

(And I see that I can use my Adafruit Thermo printer too :-) )




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Björn