Initial commit

button.ino

@@ -0,0 +1,14 @@
+volatile unsigned long lastButtonPress = millis();
+
+void buttonISRstate() {
+  if ((millis() - lastButtonPress) > 100) {
+    if (countdown > 0)
+      countdown = 0;
+    else
+      countdown = BREAK_LENGTH;
+  }
+}
+
+void buttonISRtime() {
+  lastButtonPress = millis();
+}

metronom.ino

@@ -0,0 +1,32 @@
+const uint BUZZER_PIN = 0;
+
+const uint BUTTON_LED_PIN = 5;
+const uint BUTTON_PIN = 6;
+
+const int BREAK_LENGTH = 300000;
+const int BREAK_STEP = 2000;
+
+volatile int countdown = 0;
+int step;
+
+void setup() {
+  pinMode(BUTTON_PIN, INPUT_PULLUP);
+  // Order of ISRs matter: RISING should be invoked first
+  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonISRtime, CHANGE);
+  attachInterrupt(digitalPinToInterrupt(BUTTON_PIN), buttonISRstate, RISING);
+}
+
+void loop() {
+  if (countdown > 0) {
+    step = min(BREAK_STEP, countdown);
+    countdown -= step;
+    
+    digitalWrite(BUTTON_LED_PIN, HIGH);
+    delay(min(BREAK_STEP/2, step));
+    digitalWrite(BUTTON_LED_PIN, LOW);
+    delay(max(step-BREAK_STEP/2, 0));
+  } else {
+    tone(BUZZER_PIN, 1000, 100);
+    delay(1000);
+  }
+}