I'm trying to create a device that you plug into any windows computer via usb and and than "send" a keyboard output to the computer (alt + F4) to close the active window as a prank.
My first instinct was to take apart a wireless keyboard and use that, but it turned out to be more difficult that anticipated due to the delicate circuits, so I decided to go for an Arduino Leonardo.
My question is: Do you need the Arduino Software or any other specific software on an computer to use the Leonardo as a keyboard?
No, you do not need any additional software for the keyboard part of the Leonardo
BUT
When you plug a Leonardo to a Windows computer it has never been plugged in before, Windows will ask for a driver for the Leonardo.
Why?
Because the computer recognizes the Leonardo not only as a keyboard but also as some "serial over USB device". This is why Windows asks for a driver.
[By the way: this is the German language part of the forum]
What I have done in (maybe) similar situations: I "hacked" a (cheap) standard keyboard, took it apart, threw away all the physical keys, kept the keyboard "controller" inside the keyboard. Then found out what pins to connect to get the keystrokes i needed and used a small microcontroller to "press" the desired keys.
Other option, I also used several times: Create a HID/keyboard with VUSB, an ATtiny45 or 85 (Examples) and only few other parts.
