// Arduino AVR Button and LED Test Using Interrupts

// Copyright (C)2025-2026, Philip Munts dba Munts Technologies.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
//   this list of conditions and the following disclaimer.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

// Hardware configuration (bottom to top):
//
// Arduino Uno R3 (5V logic!)
// Momentary switch plugged into D3 and GND

#include <Arduino.h>

// GPIO pin assignments:

#define Button 3   // Active low interrupt
#define LED    13  // Active high

// Button Input Interrupt Service Routine

void EdgeHandler(void)
{
  digitalWrite(LED, !digitalRead(Button));
}

void setup()
{
  Serial.begin(115200);
  Serial.println("Arduino AVR Button and LED Test Using Interrupts");
  Serial.setTimeout(10000);

  pinMode(Button, INPUT_PULLUP);
  pinMode(LED, OUTPUT);

  digitalWrite(LED, !digitalRead(Button));

  attachInterrupt(digitalPinToInterrupt(Button), EdgeHandler, CHANGE);
}

void loop()
{
  Serial.println("Tick...");
  delay(1000);
}