Welcome to the Ada for micro:bit series where we look at simple examples to learn how to program the BBC micro:bit with Ada.
If you haven't already, please follow the instructions in Part 1 to setup your development environment.
In this third part we will see how to control the output state of a micro:bit pin by lighting an LED.
- A breadboard
- An LED
- A 470 ohm resistor
- A couple of wires to connect them all
Wiring the LED directly from the output pin to ground will make it burn, so we have to add a resistor to limit the flow of current.
To control the IO pin we are going to use the procedure
Set of the package
procedure Set (Pin : Pin_Id; Value : Boolean) with Pre => Supports (Pin, Digital);
- Pin : The id of the pin that we want to control as digital output
- Value : A Boolean that says if we want the pin to be high (True) or low (False)
- The procedure
Sethas a precondition that the pin must support digital IO.
We also use the procedure
Delay_Ms of the package
MicroBit.Time to stop the program for a short amount of time.
Here is the full code of the example:
with MicroBit.IOs; with MicroBit.Time; procedure Main is begin -- Loop forever loop -- Turn on the LED connected to pin 0 MicroBit.IOs.Set (0, True); -- Wait 500 milliseconds MicroBit.Time.Delay_Ms (500); -- Turn off the LED connected to pin 0 MicroBit.IOs.Set (0, False); -- Wait 500 milliseconds MicroBit.Time.Delay_Ms (500); end loop; end Main;
Following the instructions of Part 1 you can open this example (Ada_Drivers_Library-master\examples\MicroBit\digital_out\digital_out.gpr), compile and program it on your micro:bit.
See you next week for another Ada project on the micro:bit.
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