diff --git a/bme280.ino b/bme280.ino
new file mode 100644
index 0000000..93271c8
--- /dev/null
+++ b/bme280.ino
@@ -0,0 +1,23 @@
+#include "Seeed_BME280.h"
+
+BME280 sensor;
+float highTemp = 0.0, lowTemp = 0.0;
+const float blindZone = 0.03;
+
+void initBME280() {
+  sensor.init();
+}
+
+void readTemperature() {
+  float newTemperature = sensor.getTemperature();
+
+  if (newTemperature > highTemp) {
+    temperature = newTemperature;
+    highTemp = newTemperature;
+    lowTemp = highTemp - blindZone;
+  } else if (newTemperature < lowTemp) {
+    temperature = newTemperature;
+    lowTemp = newTemperature;
+    highTemp = lowTemp + blindZone;
+  };
+}
diff --git a/button.ino b/button.ino
index 9fd0b9b..a29d8c5 100644
--- a/button.ino
+++ b/button.ino
@@ -1,11 +1,24 @@
 volatile unsigned long lastButtonPress = millis();
 
+// Debouncing na timerze:
+// https://github.com/khoih-prog/TimerInterrupt/blob/master/examples/SwitchDebounce/SwitchDebounce.ino
+void initButton() {
+  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 buttonISRstate() {
   if ((millis() - lastButtonPress) > 100) {
-    if (countdown > 0)
+    if (countdown < 0)
       countdown = 0;
-    else
-      countdown = BREAK_LENGTH;
+    else if (countdown == 0)
+      countdown = COUNTDOWN;
+    else {
+      countdown = -1;
+      digitalWrite(BUTTON_LED_PIN, LOW);
+    }
   }
 }
 
diff --git a/buzzer.ino b/buzzer.ino
new file mode 100644
index 0000000..39ff25c
--- /dev/null
+++ b/buzzer.ino
@@ -0,0 +1,22 @@
+SAMDTimer BuzzerTimer(TIMER_TC5);
+
+bool attached = false;
+
+void initBuzzer() {
+  pinMode(BUZZER_PIN, OUTPUT);
+}
+
+void buzzerISR() {
+  digitalWrite(BUZZER_PIN, !digitalRead(BUZZER_PIN));
+}
+
+void buzz() {
+  if (attached)
+    BuzzerTimer.enableTimer();
+  else
+    BuzzerTimer.attachInterrupt(BUZZER_FREQ *2, buzzerISR);
+}
+
+void noBuzz() {
+  BuzzerTimer.disableTimer();
+}
diff --git a/metronom.ino b/metronom.ino
index dbf53f7..f6a369b 100644
--- a/metronom.ino
+++ b/metronom.ino
@@ -1,32 +1,50 @@
+#include "SAMDTimerInterrupt.h"
+#include "SAMD_ISR_Timer.h"
+
+SAMDTimer TaskTimer(TIMER_TC3);
+SAMD_ISR_Timer TasksISRs;
+
+void TasksHandler(void) { TasksISRs.run(); }
+
+
+const int COUNTDOWN = 240;
+const int PERIOD_MS = 1000;
+const int BUZZER_FREQ = 300;
+
+const uint BUTTON_PIN = 6;
+const uint BUTTON_LED_PIN = 5;
 const uint BUZZER_PIN = 0;
 
-const uint BUTTON_LED_PIN = 5;
-const uint BUTTON_PIN = 6;
-
-const int BREAK_LENGTH = 240000;
-const int BREAK_STEP = 2000;
-
-volatile int countdown = 0;
-int step;
+/* Metronome state is expressed by countdown:
+ *  -1 - IDLE
+ *   0 - BEATING
+ *  >0 - COUNTDOWN
+ */
+volatile int countdown = -1;
+volatile float temperature = 0.0;
 
 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);
+  initButton();
+  initBME280();
+  initBuzzer();
+  initTube();
+
+  TaskTimer.attachInterruptInterval_MS(20, TasksHandler);
+  TasksISRs.setInterval(PERIOD_MS, runMetronome);
+  TasksISRs.setInterval(PERIOD_MS, readTemperature);
+  // TODO: move display from ISR to loop()
+  TasksISRs.setInterval(200, updateTube);
 }
 
-void loop() {
+void runMetronome() {
   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, 300, 100);
-    delay(1000);
+    countdown -= 1;
+
+    digitalWrite(BUTTON_LED_PIN, countdown % 2 ? HIGH : LOW);
+  } else if (countdown == 0) {
+    TasksISRs.setTimeout(100, noBuzz);
+    buzz();
   }
 }
+
+void loop() {}
diff --git a/tube.ino b/tube.ino
new file mode 100644
index 0000000..9d998d7
--- /dev/null
+++ b/tube.ino
@@ -0,0 +1,30 @@
+#include "grove_alphanumeric_display.h"
+
+Seeed_Digital_Tube tube;
+char tubeText[5] = "";
+
+void initTube() {
+  // Wire initialized by BME280 sensor
+  tube.setTubeType(TYPE_4, TYPE_4_DEFAULT_I2C_ADDR);
+  tube.setBrightness(15);
+  tube.setBlinkRate(BLINK_OFF);
+}
+
+void updateTube() {
+  char newText[5];
+  bool highPoint = false, lowPoint = false;
+
+  if (countdown <= 0) {
+    sprintf(newText, "%4u", (unsigned int) (temperature * 100.0));
+    lowPoint = true;
+  } else {
+    sprintf(newText, "%4u", countdown);
+  }
+
+  if (strcmp(tubeText, newText)) {
+    strcpy(tubeText, newText);
+    tube.displayString(tubeText);
+    tube.setPoint(highPoint, lowPoint);
+    tube.display();
+  }
+}