Keyboard press how it works?

Projects Programming
1

Hi everyone !

I want to design a simple behaviour using Keyboard.press. My goal is to make arduino ables to print the letter I already assigned for three times. To do that I used this code:

#include<Keyboard.h>
void setup() {

 
Serial.begin(9600);
Keyboard.begin();
}

void loop() {

Keyboard.press('w');
          delay(1500);
          Keyboard.release('w');
          Keyboard.end();

}

It works but there is a little glitch because the delay is settled to print to me 3 letters " W ", the fact is that the first 2 letters are printed smoothly whereas the last one takes few seconds to be printed.

How can make the print part smoother ? The delay is not the appropriate one ?

2

Why did you call the 'end()' method?

3

You are using the operating system's auto-repeat timing to get your three repeats. That won't work if you move to a different system or change OS keyboard settings.

Better would be to press and release the key three times.

#include <Keyboard.h>

void setup()
{
  Keyboard.begin();

  Keyboard.press('w');
  delay(100);
  Keyboard.release('w');

  delay(500);

  Keyboard.press('w');
  delay(100);
  Keyboard.release('w');

  delay(500);

  Keyboard.press('w');
  delay(100);
  Keyboard.release('w');

  Keyboard.end();
}

void loop() {}
4

My aim is to simulate the natural behaviour of when you keep pressing the letter in your keyboard, because I want to use that mechanisms to automatize some action on FIFA game, for that reason I need to load the shot keeping the letter down for a while example

5

Why fight with the auto-repeat when you can completely control the key press timing from the Arduino?

It doesn't seem necessary for the purpose you describe, to use auto repeat.

6

Because I read only that I can risk that my arduino may go to loop and will be impossible to configure again

7

Oh. Then just ignore what you see in the text input. The game probably uses raw keyboard events and doesn't see character input events generated by the OS.

8

Did you read it on the internet? :slight_smile:

9

So, do you think is fine as I already coded ?

10

Does it work with the game? If it's an absolute requirement that you send exactly 3 key presses, then you are not doing it a good way.

11

I would not put that code in loop() unless you want it to run over and over. If you want to maintain control I would not include Keyboard.end();.

12

There are a few things that can go wrong when using Arduinos as a HID but that will never be unrecoverable.

  1. You spam your PC with text; that is problematic because when you try to modify your sketch with the board connected that text will go into the IDE.
  2. You use Keyboard.press() but forget Keyboard.release(); the pressed key will be stuck in the PC.

The below code adds a safety pin to your code and will only send keyboard commands if that pin is connected to ground; if it's not connected to ground it will release the keys that you might have forgotten to release.

#include <Keyboard.h>
#define SAFETY_ENABLED HIGH
const uint8_t safetyPin = A1;

void setup()
{
  Serial.begin(115200);
  while (!Serial);

  pinMode(safetyPin, INPUT_PULLUP);
}

void loop()
{
  static bool isPressed = false;
  // check if the safetyPin is connected to ground
  if (digitalRead(safetyPin) != SAFETY_ENABLED)
  {
    // press the left shift key once
    if (isPressed == false)
    {
      Keyboard.press(KEY_LEFT_SHIFT);
      isPressed = true;
      Serial.println("Key pressed");
    }
  }
  // if the safety pin is not connected to ground
  else
  {
    // release any key that might be stuck
    Keyboard.releaseAll();
    Serial.println("All keys released");
    isPressed = false;
  }

  delay(500);
}

Your actions can go inside this part

  if (digitalRead(safetyPin) != SAFETY_ENABLED)
  {
  }

There is something more generic that can go wrong; part of the code that you upload provides the USB functionality; if you write crappy code that overwrites variables used by that specific code for the USB, you will experience upload problems; easy to resolve (if you know how).