buttons

Buttons Example

In this example we will see how to use the four buttons of the nRF52 Development Kit.

Code

To know if a button is pressed or not, we will use the procedure State of the NRF52_DK.Buttons package.

   type Button_State is (Pressed, Released);

   type Button_Id is (Button_1, Button_2, Button_3, Button_4);

   function State (Button : Button_Id) return Button_State;

Arguments:

• Button : The Id of the button that we want to check. There are four Ids: Button_1, Button_2, Button_3, and Button_4 which correspond to the silkscreen on the board.

Return value:

The procedure State return the Button_State that can be either Pressed or Released.

Here is the code:

with NRF52_DK.Buttons; use NRF52_DK.Buttons;
with NRF52_DK.LEDs; use NRF52_DK.LEDs;
with NRF52_DK.Time;

procedure Main is
begin
   Initialize_LEDs;
   loop
      Turn_Off (LED1);
      Turn_Off (LED2);
      Turn_Off (LED3);
      Turn_Off (LED4);
      if NRF52_DK.Buttons.State (Button_1) = Pressed then
         Turn_On (LED1);
      end if;

      if NRF52_DK.Buttons.State (Button_2) = Pressed then
         Turn_On (LED2);
      end if;

      if NRF52_DK.Buttons.State (Button_3) = Pressed then
         Turn_On (LED3);
      end if;

      if NRF52_DK.Buttons.State (Button_4) = Pressed then
         Turn_On (LED4);
      end if;

      NRF52_DK.Time.Delay_Ms (200);
   end loop;
end Main;