Added arduino libs

libraries/EnableInterrupt/examples/Debounce/Debounce.ino

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+/*
+ *  This example shows how to combine the EnableInterrupt
+ *  library with some simple debouncing code for reading
+ *  button presses consistently.
+ *  
+ *  The interrupt is attached to digital input 5 and the
+ *  service routine just toggles the onboard LED status.
+ *  
+ *  Tested on: ATmega328P
+ *  
+ *  Example by Lorenzo Cafaro <lorenzo@ibisco.net>
+ *
+*/
+
+#include <EnableInterrupt.h>
+
+#define BUTTON_PIN 5
+#define DEBOUNCE_DELAY 100 // in ms
+
+uint32_t last_interrupt_time = 0;
+uint8_t led_status = 0;
+
+void setup() {
+  pinMode(BUTTON_PIN, INPUT);
+  pinMode(LED_BUILTIN, OUTPUT);
+  enableInterrupt(BUTTON_PIN, isr_handler, RISING);
+}
+
+void loop() {
+  // zZz
+}
+
+void isr_handler() {
+  uint32_t interrupt_time = millis();
+
+  if (interrupt_time - last_interrupt_time > DEBOUNCE_DELAY) {
+    led_status = !led_status;
+    digitalWrite(LED_BUILTIN, led_status);
+  }
+
+  last_interrupt_time = interrupt_time;
+}