diff --git a/firmware/include/app.h b/firmware/include/app.h
index d8b9b58..cf2353a 100644
--- a/firmware/include/app.h
+++ b/firmware/include/app.h
@@ -1,10 +1,25 @@
-#ifndef ZAUBERSTAB_APP_H
-#define ZAUBERSTAB_APP_H
+#pragma once
 
 struct App {
-    void (*loop)(void);
-    void (*setup)(void);
+    void virtual init() = 0;
+    void virtual deinit() = 0;
+    void virtual loop() = 0;
 };
 
-struct App 
-#endif
\ No newline at end of file
+struct BeatDetectApp : public App {
+    void init();
+    void deinit();
+    void loop();
+};
+
+struct VuMeterApp: public App {
+    void init();
+    void deinit();
+    void loop();
+};
+
+struct FFTTestApp: public App {
+    void init();
+    void deinit();
+    void loop();
+};
\ No newline at end of file
diff --git a/firmware/include/zauberstab.h b/firmware/include/zauberstab.h
index 7c85f25..57a875b 100644
--- a/firmware/include/zauberstab.h
+++ b/firmware/include/zauberstab.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "Arduino.h"
 #include <FastLED.h>
 
 #define LED_PIN 12
diff --git a/firmware/src/beat_detect.cpp b/firmware/src/applications/beat_detect.cpp
similarity index 97%
rename from firmware/src/beat_detect.cpp
rename to firmware/src/applications/beat_detect.cpp
index 76de9bd..4587887 100644
--- a/firmware/src/beat_detect.cpp
+++ b/firmware/src/applications/beat_detect.cpp
@@ -1,5 +1,6 @@
 #include <algorithm>
 
+#include "app.h"
 #include "biquad.h"
 #include "pt1.h"
 #include "zauberstab.h"
@@ -80,15 +81,18 @@ set_filter()
     }
 }
 
-void setup()
+void BeatDetectApp::init()
 {
-    zauberstab_init();
-    Serial.begin(250000);
     set_filter();
     initial_time = micros();
 }
 
-void loop()
+void BeatDetectApp::deinit()
+{
+
+}
+
+void BeatDetectApp::loop()
 {
     float sample = get_sample();
     energy += std::abs(sample) * std::abs(sample);
diff --git a/firmware/src/applications/fft_test.cpp b/firmware/src/applications/fft_test.cpp
new file mode 100644
index 0000000..1d9956d
--- /dev/null
+++ b/firmware/src/applications/fft_test.cpp
@@ -0,0 +1,70 @@
+#include "app.h"
+#include "fft.h"
+#include "zauberstab.h"
+
+#define N_SAMPLES 256
+
+std::complex<float> samples[N_SAMPLES];
+std::complex<float> z[N_SAMPLES];
+double vReal[N_SAMPLES];
+double vImag[N_SAMPLES];
+uint32_t sample_counter = 0;
+unsigned long max_dt = 0;
+unsigned long last_sample = 0;
+
+void FFTTestApp::init()
+{
+}
+
+void FFTTestApp::deinit()
+{
+
+}
+
+void FFTTestApp::loop()
+{
+    if (micros() - last_sample >= 200)
+    {
+        unsigned long dt = micros() - last_sample;
+        last_sample = micros();
+        if (dt > max_dt)
+        {
+            max_dt = dt;
+        }
+
+        samples[sample_counter++] = get_sample();
+
+        if (sample_counter == N_SAMPLES)
+        {
+            unsigned long start = micros();
+            fft(samples, z, N_SAMPLES);
+            unsigned long end = micros();
+
+            float max = 0.f;
+            for (int i = 0; i < N_SAMPLES / 2; i++)
+            {
+                float v = std::log10(std::abs(z[i]));
+                if (v > max)
+                {
+                    max = v;
+                }
+            }
+
+            for (int i = 0; i < N_SAMPLES / 2; i++)
+            {
+                float v = std::log10(std::abs(z[i]));
+                if (v < 2.f)
+                {
+                    v = 0.f;
+                }
+                uint8_t led_value = v * 20;
+                leds[i].setRGB(led_value, led_value, led_value);
+            }
+
+            sample_counter = 0;
+            start = micros();
+            FastLED.show();
+            end = micros();
+        }
+    }
+}
\ No newline at end of file
diff --git a/firmware/temp/vumeter.cpp b/firmware/src/applications/vumeter.cpp
similarity index 88%
rename from firmware/temp/vumeter.cpp
rename to firmware/src/applications/vumeter.cpp
index 6c95c0d..03533e5 100644
--- a/firmware/temp/vumeter.cpp
+++ b/firmware/src/applications/vumeter.cpp
@@ -1,3 +1,4 @@
+#include "app.h"
 #include "pt1.h"
 #include "zauberstab.h"
 
@@ -9,17 +10,19 @@ float vu_filt = 0.0f;
 float vu_filt_slow = 0.0f;
 float dt;
 
-Pt1<float> vu_pt1_fast{1.f, 1.f};
-Pt1<float> vu_pt1_slow{1.f, 0.05f};
+Pt1<float> vu_pt1_fast{1.f, 0.05f};
+Pt1<float> vu_pt1_slow{1.f, 1.f};
 
-void setup()
+void VuMeterApp::init()
 {
-    zauberstab_init();
-    Serial.begin(115200);
     FastLED.setBrightness(100);
 }
 
-void loop()
+void VuMeterApp::deinit()
+{
+}
+
+void VuMeterApp::loop()
 {
     if (micros() - last_sample_time >= 500)
     {
diff --git a/firmware/src/main.cpp b/firmware/src/main.cpp
new file mode 100644
index 0000000..1620cc6
--- /dev/null
+++ b/firmware/src/main.cpp
@@ -0,0 +1,36 @@
+#include "zauberstab.h"
+#include <vector>
+#include "app.h"
+
+struct BeatDetectApp beat_detect_app{};
+struct VuMeterApp vu_meter_app {};
+struct FFTTestApp fft_test_app {};
+
+std::vector<std::reference_wrapper<App>> apps = {
+    std::ref<App>(beat_detect_app),
+    std::ref<App>(vu_meter_app),
+    std::ref<App>(fft_test_app),
+};
+
+unsigned int current_app = 0;
+unsigned int next_app;
+
+void setup()
+{
+    next_app = current_app;
+    zauberstab_init();
+    Serial.begin(115200);
+
+    apps[current_app].get().init();
+}
+
+void loop()
+{
+    if (next_app != current_app) {
+        apps[current_app].get().deinit();
+        apps[next_app].get().init();
+        current_app = next_app;
+    }
+
+    apps[current_app].get().loop();
+}
\ No newline at end of file
diff --git a/firmware/temp/main.cpp b/firmware/temp/main.cpp
deleted file mode 100644
index 4ea6ade..0000000
--- a/firmware/temp/main.cpp
+++ /dev/null
@@ -1,10 +0,0 @@
-#include "zauberstab.h"
-
-void setup()
-{
-  zauberstab_init();
-}
-
-void loop()
-{
-}
\ No newline at end of file