Update arduino demos.

  * demos-arduino-due/debounce_hardware.adb: added explanatory comment.
    (Handler): ISR_Register's name has changed (to PIOA_ISR_Register :-)
  * demos-arduino-due/debounce_software.adb: likewise.
    (Button'Spec): added Outstanding_Interrupts, Suppress_Interrupts_Until.
    (Button.Wait): only clear Trigger when there are no outstanding
      interrupts left.
    (Button.Handler): rewrite.
    (T): flash the LED each time Button.Wait is released.
  * demos-arduino-due/.gdbinit: copied from ../test-arduino-due.

demos-arduino-due/.gdbinit

@@ -0,0 +1,2 @@
+target remote :2331
+load

demos-arduino-due/debounce_hardware.adb

@@ -1,4 +1,4 @@
---  Copyright (C) 2016, 2019 Free Software Foundation, Inc.
+--  Copyright (C) 2016, 2019, 2020 Free Software Foundation, Inc.
 
 --  This file is part of the Cortex GNAT RTS package.
 --
@@ -18,6 +18,12 @@
 
 --  This package, in file debounce_hardware.adb, is the
 --  hardware-implemented version of debouncing.
+--
+--  To run, connect a pushbutton between GND and pin 53. On button-up,
+--  the LED will flash a number of times indicating how many button-up
+--  interrupts were received,
+--
+--  To check, comment out the line where debounce is enabled (:132).
 
 with Ada.Interrupts.Names;
 with Ada.Real_Time;
@@ -63,7 +69,7 @@ package body Debounce_Impl is
       end Wait;
 
       procedure Handler is
-         Status : constant ISR_Register := PIOB_Periph.ISR;
+         Status : constant PIOA_ISR_Register := PIOB_Periph.ISR;
       begin
          if Status.Arr (Input_Pin) /= 0 then
             Interrupts := Interrupts + 1;
@@ -122,7 +128,7 @@ begin
    --  .. debounce vs glitch ..
    PIOB_Periph.DIFSR.Arr := (Input_Pin => 1, others => 0);
 
-   --  .. enable debounce ..
+   --  .. enable debounce (comment-out to disable) ..
    PIOB_Periph.IFER.Arr := (Input_Pin => 1, others => 0);
 
    --  .. enable interrupts.

demos-arduino-due/debounce_software.adb

@@ -1,4 +1,4 @@
---  Copyright (C) 2016, 2019 Free Software Foundation, Inc.
+--  Copyright (C) 2016, 2019, 2020 Free Software Foundation, Inc.
 
 --  This file is part of the Cortex GNAT RTS package.
 --
@@ -16,8 +16,12 @@
 --  along with this program; see the file COPYING3.  If not, see
 --  <http://www.gnu.org/licenses/>.
 
---  This package, in file debounce_hardware.adb, is the
+--  This package, in file debounce_software.adb, is the
 --  software-implemented version of debouncing.
+--
+--  To run, connect a pushbutton between GND and pin 53. On button-up,
+--  the LED will flash a number of times indicating how many button-up
+--  interrupts were received,
 
 with Ada.Interrupts.Names;
 with Ada.Real_Time;
@@ -45,6 +49,9 @@ package body Debounce_Impl is
       entry Wait;
    private
       Triggered : Boolean := False;
+      Outstanding_Interrupts : Natural := 0;
+      Suppress_Interrupts_Until : Ada.Real_Time.Time
+        := Ada.Real_Time.Time_First;
       procedure Handler
       with
         Attach_Handler => Ada.Interrupts.Names.PIOB_IRQ,
@@ -56,14 +63,25 @@ package body Debounce_Impl is
    protected body Button is
       entry Wait when Triggered is
       begin
-         Triggered := False;
+         Outstanding_Interrupts := Outstanding_Interrupts - 1;
+         if Outstanding_Interrupts = 0 then
+            Triggered := False;
+         end if;
       end Wait;
 
       procedure Handler is
-         Status : constant ISR_Register := PIOB_Periph.ISR;
+         Status : constant PIOA_ISR_Register := PIOB_Periph.ISR;
+         Now : constant Ada.Real_Time.Time := Ada.Real_Time.Clock;
+         use type Ada.Real_Time.Time;
       begin
-         if Status.Arr (Input_Pin) /= 0 then
+         if Status.Arr (Input_Pin) /= 0
+           --  Pull-up is enabled, so the pin is 0 if the button is pressed
+           and then PIOB_Periph.PDSR.Arr (Input_Pin) /= 0
+           and then Now >= Suppress_Interrupts_until
+         then
             Triggered := True;
+            Outstanding_Interrupts := Outstanding_Interrupts + 1;
+            Suppress_Interrupts_Until := Now + Ada.Real_Time.Milliseconds (5);
          end if;
       end Handler;
    end Button;
@@ -77,15 +95,12 @@ package body Debounce_Impl is
       loop
          Button.Wait;
 
+         PIOB_Periph.SODR.Arr := (Output_Pin => 1, others => 0);
          delay until
-           Ada.Real_Time.Clock + Ada.Real_Time.Milliseconds (5);
-
-         --  Pull-up is enabled, so the pin is 0 if the button is pressed
-         if PIOB_Periph.PDSR.Arr (Input_Pin) /= 0 then
-            PIOB_Periph.CODR.Arr := (Output_Pin => 1, others => 0);
-         else
-            PIOB_Periph.SODR.Arr := (Output_Pin => 1, others => 0);
-         end if;
+           Ada.Real_Time.Clock + Ada.Real_Time.Milliseconds (100);
+         PIOB_Periph.CODR.Arr := (Output_Pin => 1, others => 0);
+         delay until
+           Ada.Real_Time.Clock + Ada.Real_Time.Milliseconds (100);
       end loop;
    end T;