User friendliness

Step 1) Adding control system (pin and if statement).

Author: Epipeppy

libraries/USBHID/examples/Keyboard/Keyboard.ino

@@ -1,15 +1,26 @@
+/**************************************************************
+** Brief introduction to a few HID Keyboard commands.        **
+** Unlike the other Keyboard library, this one doesn't use   **
+** the "press", "release", and "send" commands.              **
+**************************************************************/
+
 #include "PluggableUSBHID.h"
 #include "USBKeyboard.h"
 
 USBKeyboard Keyboard;
 
-void setup() {
-  // put your setup code here, to run once:
+// Arbitrary pin.
+const int CONTROL_PIN = 2;
 
+void setup() {
+  // We will use this to start/end the prints.
+  pinMode(CONTROL_PIN, INPUT_PULLUP);
 }
 
 void loop() {
-  // put your main code here, to run repeatedly:
-  delay(1000);
-  Keyboard.printf("Hello world\n\r");
+  // This will run only if the control pin is connected to ground.
+  if( digitalRead(CONTROL_PIN) == LOW){
+    delay(1000);
+    Keyboard.printf("Hello world\n\r");
+  }
 }