diff --git a/Versuch5/Core/Src/main.c b/Versuch5/Core/Src/main.c
index 1226cf2..9c19209 100644
--- a/Versuch5/Core/Src/main.c
+++ b/Versuch5/Core/Src/main.c
@@ -21,6 +21,7 @@
 #include "cmsis_os.h"
 #include "fatfs.h"
 #include "usb_host.h"
+#include "waveplayer.h"
 
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
@@ -162,12 +163,12 @@ void createGuiElements(){
 
 
 // helper to update volume value on display
-uint8_t volume = 70;
-void drawVolume(){
+uint8_t volumeVersuch4 = 70;
+void drawVolumeVersuch4(){
 		      Display_Printf( 0, 40,
 		      		LCD_COLOR_WHITE, LCD_COLOR_BLACK,
 		      		&FontBig,
-		          "%03d", volume
+		          "%03d", volumeVersuch4
 		      );
 }
 
@@ -180,7 +181,7 @@ void Task9_receiveGuiEvents(void *){
   uint8_t gui_msg = 0;
 
   //initially draw volume
-  drawVolume();
+  drawVolumeVersuch4();
 
   // receive gui events
 	while(1){
@@ -189,13 +190,13 @@ void Task9_receiveGuiEvents(void *){
 
       switch(gui_msg){
         case BUTTON_PLUS:
-          if (++volume > 100) volume = 100;
-          drawVolume();
+          if (++volumeVersuch4 > 100) volumeVersuch4 = 100;
+          drawVolumeVersuch4();
         break;
 
         case BUTTON_MINUS:
-          if (volume-- == 0) volume = 0;
-          drawVolume();
+          if (volumeVersuch4-- == 0) volumeVersuch4 = 0;
+          drawVolumeVersuch4();
           break;
 
         case BUTTON_PLAY:
@@ -338,7 +339,7 @@ void Task8_printLoad(void *){
 		Display_Printf( 0, 0,
 			LCD_COLOR_WHITE, LCD_COLOR_BLACK,
 			&FontBig,
-		  "%03d", Usage_GetUsage()
+		  "%03d%%", Usage_GetUsage()
 		);
 
     Usage_PrintStats();
@@ -388,9 +389,8 @@ int main(void)
   /* USER CODE BEGIN 2 */
 
   Usage_Init();
-
   Display_Init();
-
+  Player_Init();
   GUI_Init();
   // local variables
   uint32_t timestamp_lastCounted   = HAL_GetTick();
@@ -445,8 +445,8 @@ int main(void)
   //xTaskCreate(Task6_countButtonPresses, "Task6_countButtonPresses", 256, NULL, 0, NULL);
   //xTaskCreate(Task7_receiveQueueEvents, "Task7_receiveQueueEvents", 256, NULL, 0, NULL);
 
-  xTaskCreate(Task8_printLoad, "Task8_stats", 256, NULL, 0, NULL);
-  xTaskCreate(Task9_receiveGuiEvents, "Task9_GUI", 256, NULL, 0, NULL);
+    xTaskCreate(Task8_printLoad, "Task8_stats", 256, NULL, 0, NULL);
+  // xTaskCreate(Task9_receiveGuiEvents, "Task9_GUI", 256, NULL, 0, NULL);
 
   /* USER CODE END RTOS_THREADS */
 
diff --git a/Versuch5/Core/Src/waveplayer.c b/Versuch5/Core/Src/waveplayer.c
index de07c37..28f2581 100644
--- a/Versuch5/Core/Src/waveplayer.c
+++ b/Versuch5/Core/Src/waveplayer.c
@@ -1,66 +1,187 @@
-/*******************************************************************
-File: waveplayer.c
-Date: 29-September-2025
-Author: Peter Spindler
-Description: Functions to play a wave file. Requires functions from audio.c
- ********************************************************************/
-#include "stm32f7xx_hal.h"
-#include "audio.h"
-
-#include "FreeRTOS.h"
-#include "semphr.h"
-#include "task.h"
-
-#include "ff.h"
-#include "fatfs.h"
-
-#include "audio.h"
-#include "gui.h"
-#include "display.h"
-
-FIL WaveFile;
-#define AUDIO_BUFFER_SIZE_WORDS  (1024*8)
-uint16_t Audio_Buffer[AUDIO_BUFFER_SIZE_WORDS];
-
-void Player_Start( const char *Filename ) {
-	FRESULT res;
-	if( (res=f_open(&WaveFile, Filename , FA_READ )) != FR_OK) {
-		printf("Error: Can't open audio file %s: %d\n", Filename, res);
-		return;
-	}
-	printf("Open wavefile %s: successful\n", Filename );
-
-	Audio_SetFrequency(22050);
-	
-    /* ToDo: Fill audio buffer completely */
-    
-	Audio_Play( (uint8_t*) Audio_Buffer, sizeof(Audio_Buffer)/2 );
-}
-
-void Player_Stop( void ) {
-    Audio_Stop();
-	f_close(&WaveFile);
-}
-
-// Player_HalfTransfer_CallBack: called from DMA2_Stream4-ISR if first half of audio buffer has been transferred to SAI2
-void Player_HalfTransfer_CallBack( void ) {
-    /* ToDo: Inform Player_Task about first half*/
-}
-
-// Player_CompleteTransfer_CallBack: called from DMA2_Stream4-ISR if second half of audio buffer has been transferred to SAI2
-void Player_CompleteTransfer_CallBack( void ) {
-    /* ToDo: Inform Player_Task about second half*/
-}
-
-static void Player_Task( void *arguments ) {
-	/* ToDo */
-}
-
-void Player_Init( void ) {
-	portENABLE_INTERRUPTS(); // Workaround to re-enable interrupts after FreeRTOS functions
-    // 70: initial volume, 44100: initial sampling frequency
-	if( Audio_Init(OUTPUT_DEVICE_AUTO,70,44100) != AUDIO_OK ) {
-		printf("Error: Can't init audio!\n");
-	}
-	xTaskCreate(Player_Task,"Player", 512,NULL,0,NULL);
-}
+/*******************************************************************
+File: waveplayer.c
+Date: 29-September-2025
+Author: Peter Spindler
+Description: Functions to play a wave file. Requires functions from audio.c
+ ********************************************************************/
+#include "stm32f7xx_hal.h"
+#include "audio.h"
+
+#include "FreeRTOS.h"
+#include "semphr.h"
+#include "task.h"
+
+#include "ff.h"
+#include "fatfs.h"
+
+#include "audio.h"
+#include "gui.h"
+#include "display.h"
+#include <stdio.h>
+#include <string.h>
+
+#define BUTTON_PLUS 0
+#define BUTTON_MINUS 1
+#define BUTTON_PLAY 2
+#define BUTTON_PAUSE 3
+#define BUTTON_STOP 4
+
+enum playerState {PAUSED, PLAYING, STOPPED} playerState = PLAYING;
+
+FIL WaveFile;
+#define AUDIO_BUFFER_SIZE_WORDS  (1024*8)
+uint16_t Audio_Buffer[AUDIO_BUFFER_SIZE_WORDS];
+#define PLAYER_NOTIFY_HALF   (1UL << 0)
+#define PLAYER_NOTIFY_FULL   (1UL << 1)
+static TaskHandle_t PlayerTaskHandle = NULL;
+
+
+SemaphoreHandle_t Semphr_FillBuffer = NULL;
+uint8_t fillFlag = 0;
+
+// helper to update volume value on display
+uint8_t volume = 70;
+void drawVolume(){
+		      Display_Printf( 0, 40,
+		      		LCD_COLOR_WHITE, LCD_COLOR_BLACK,
+		      		&FontBig,
+		          "%03d", volume
+		      );
+}
+
+void Player_Start( const char *Filename ) {
+	FRESULT res;
+	printf("debug: Player_Start opening file...\n");
+	// FIXME: Currently is stuck / crashes here (when stopping, then playing again) ===================
+	if( (res=f_open(&WaveFile, Filename , FA_READ )) != FR_OK) {
+		printf("Error: Can't open audio file %s: %d\n", Filename, res);
+		return;
+	}
+	printf("debug: Player_start finished opening file. \n");
+	printf("Open wavefile %s: successful\n", Filename );
+
+	Audio_SetFrequency(22050);
+
+	// fill audio buffer completely
+	UINT bytesRead = 0;
+	res = f_read(&WaveFile, Audio_Buffer, sizeof(Audio_Buffer), &bytesRead);
+	if( res != FR_OK ) {
+		printf("Error: Can't read audio file %s: %d\n", Filename, res);
+		f_close(&WaveFile);
+		return;
+	}
+
+	Audio_Play( (uint8_t*) Audio_Buffer, sizeof(Audio_Buffer)/2 );
+}
+
+void Player_Stop( void ) {
+    Audio_Stop();
+	f_close(&WaveFile);
+}
+
+// Player_HalfTransfer_CallBack: called from DMA2_Stream4-ISR if first half of audio buffer has been transferred to SAI2
+void Player_HalfTransfer_CallBack( void ) {
+	fillFlag = 0;
+	//printf("give 0\n");
+	xSemaphoreGiveFromISR(Semphr_FillBuffer, NULL);
+}
+
+// Player_CompleteTransfer_CallBack: called from DMA2_Stream4-ISR if second half of audio buffer has been transferred to SAI2
+void Player_CompleteTransfer_CallBack( void ) {
+	fillFlag = 1;
+	//printf("give 1\n");
+	xSemaphoreGiveFromISR(Semphr_FillBuffer, NULL);
+}
+
+static void Player_Task( void *arguments ) {
+	UINT bytesRead = 0;
+	uint32_t notifyValue = 0;
+	drawVolume();
+	while(1) {
+		// 1. fill audio buffer if requested 
+    	if (xSemaphoreTake(Semphr_FillBuffer, pdMS_TO_TICKS(20))){
+			if (playerState != PLAYING) continue;
+			if (fillFlag == 0){ // half flag -> fill first half
+				if( f_read(&WaveFile, &Audio_Buffer[0], sizeof(Audio_Buffer)/2, &bytesRead) != FR_OK ) {
+					bytesRead = 0;
+				}
+				if( bytesRead < AUDIO_BUFFER_SIZE_WORDS/2 ) {
+					printf("error reading bytes, stopping playback\n");
+					Player_Stop();
+					playerState = STOPPED;
+				}
+			}
+
+			else if (fillFlag == 1){ // complete flag -> fill second half
+				bytesRead = 0;
+				if( f_read(&WaveFile, &Audio_Buffer[AUDIO_BUFFER_SIZE_WORDS/2], sizeof(Audio_Buffer)/2, &bytesRead) != FR_OK ) {
+					bytesRead = 0;
+				}
+				if( bytesRead < AUDIO_BUFFER_SIZE_WORDS/2 ) {
+					printf("error reading bytes, stopping playback\n");
+					Player_Stop();
+					playerState = STOPPED;
+				}
+			}
+		}
+
+		// 2. run player control (handle gui events)
+	  	//printf("running player control...\n");
+  		  uint8_t gui_msg = 0;
+  		  if (xQueueReceive(GUIQueue, &gui_msg, pdMS_TO_TICKS(0))){
+  		    printf("Received GUI event %d\n", gui_msg);
+
+  		    switch(gui_msg){
+  		      case BUTTON_PLUS:
+  		        if (++volume > 100) volume = 100;
+  		        drawVolume();
+				Audio_SetVolume(volume);
+  		      break;
+
+  		      case BUTTON_MINUS:
+  		        if (volume-- == 0) volume = 0;
+  		        drawVolume();
+				Audio_SetVolume(volume);
+  		        break;
+
+  		      case BUTTON_PLAY:
+  		        printf("Play\r\n");
+				if (playerState == STOPPED){
+					printf("was stopped, starting player from start\n");
+    				//	FATFS fs;
+    				//	printf("1. mounting filesystem...\n");
+    				//	f_mount(&fs, "/", 0);
+					Player_Start("audio.wav");
+				} else if (playerState == PAUSED){
+					printf("was paused, resuming...\n");
+					Audio_Resume();
+				}
+				playerState = PLAYING;
+  		      break;
+
+  		      case BUTTON_PAUSE:
+  		        printf("Pausing\r\n");
+				Audio_Pause();
+				playerState = PAUSED;
+  		      break;
+
+  		      case BUTTON_STOP:
+  		        printf("Stopping player\r\n");
+				Player_Stop();
+				playerState = STOPPED;
+  		      break;
+  		    }
+  		  }
+			vTaskDelay(pdMS_TO_TICKS(10));
+	}
+}
+
+void Player_Init( void ) {
+	portENABLE_INTERRUPTS(); // Workaround to re-enable interrupts after FreeRTOS functions
+    // 70: initial volume, 44100: initial sampling frequency
+	if( Audio_Init(OUTPUT_DEVICE_AUTO,70,44100) != AUDIO_OK ) {
+		printf("Error: Can't init audio!\n");
+	}
+  	Semphr_FillBuffer = xSemaphoreCreateBinary();
+	xTaskCreate(Player_Task,"Player", 512,NULL,0,&PlayerTaskHandle);
+}
diff --git a/Versuch5/USB_HOST/App/usb_host.c b/Versuch5/USB_HOST/App/usb_host.c
index 606cf89..8282745 100644
--- a/Versuch5/USB_HOST/App/usb_host.c
+++ b/Versuch5/USB_HOST/App/usb_host.c
@@ -28,6 +28,9 @@
 
 /* USER CODE BEGIN Includes */
 
+#include "waveplayer.h"
+#include "fatfs.h"
+
 /* USER CODE END Includes */
 
 /* USER CODE BEGIN PV */
@@ -94,6 +97,9 @@ void MX_USB_HOST_Init(void)
 /*
  * user callback definition
  */
+
+ #define VERSUCH_5 1
+
 static void USBH_UserProcess  (USBH_HandleTypeDef *phost, uint8_t id)
 {
   /* USER CODE BEGIN CALL_BACK_1 */
@@ -110,7 +116,26 @@ static void USBH_UserProcess  (USBH_HandleTypeDef *phost, uint8_t id)
   case HOST_USER_CLASS_ACTIVE:
   Appli_state = APPLICATION_READY;
   printf("USB device ready\n\r");
+#if VERSUCH_4
   versuch4_write_file();
+
+#else if VERSUCH_5
+
+    FATFS fs;
+    FRESULT res;
+
+    // mount fs
+    printf("1. mounting filesystem...\n");
+    res = f_mount(&fs, "/", 0);
+    if (res != FR_OK){
+        printf("Fehler beim mounten vom dateisystem\n");
+        return;
+    }
+    
+    printf("2. starting playback...");
+    Player_Start("audio.wav");
+#endif
+
   break;
 
   case HOST_USER_CONNECTION: