diff --git a/examples/device/nrf52840_freertos/src/main.c b/examples/device/nrf52840_freertos/src/main.c
index a0c418920..6fb76a84d 100644
--- a/examples/device/nrf52840_freertos/src/main.c
+++ b/examples/device/nrf52840_freertos/src/main.c
@@ -61,9 +61,6 @@
 //--------------------------------------------------------------------+
 void print_greeting(void);
 void led_blinky_cb(TimerHandle_t xTimer);
-void cdc_task(void* params);
-void usb_hid_task(void* params);
-
 
 /*------------- MAIN -------------*/
 int main(void)
@@ -78,10 +75,16 @@ int main(void)
   tusb_init();
 
   // Create task
+#if CFG_TUD_CDC
+  extern void cdc_task(void* params);
   xTaskCreate( cdc_task, "cdc", 256, NULL, 2, NULL);
+#endif
+
+#if CFG_TUD_HID
+  extern void usb_hid_task(void* params);
+#endif
 
   vTaskStartScheduler();
-
   NVIC_SystemReset();
 
   return 0;
@@ -90,6 +93,7 @@ int main(void)
 //--------------------------------------------------------------------+
 // USB CDC
 //--------------------------------------------------------------------+
+#if CFG_TUD_CDC
 void cdc_task(void* params)
 {
   (void) params;
@@ -111,10 +115,12 @@ void cdc_task(void* params)
     taskYIELD();
   }
 }
+#endif
 
 //--------------------------------------------------------------------+
 // USB HID
 //--------------------------------------------------------------------+
+#if CFG_TUD_HID
 void usb_hid_task(void* params)
 {
   (void) params;
@@ -170,6 +176,7 @@ void tud_hid_generic_set_report_cb(uint8_t report_id, hid_report_type_t report_t
 {
   // TODO not Implemented
 }
+#endif
 
 //--------------------------------------------------------------------+
 // tinyusb callbacks
diff --git a/examples/device/nrf52840_freertos/src/msc_flash_qspi.c b/examples/device/nrf52840_freertos/src/msc_flash_qspi.c
index d8058d8ac..53bdc5a71 100644
--- a/examples/device/nrf52840_freertos/src/msc_flash_qspi.c
+++ b/examples/device/nrf52840_freertos/src/msc_flash_qspi.c
@@ -47,19 +47,6 @@ void flash_flush (void);
 //--------------------------------------------------------------------+
 // MACRO TYPEDEF CONSTANT ENUM DECLARATION
 //--------------------------------------------------------------------+
-enum
-{
-  FLASH_STATE_IDLE,
-  FLASH_STATE_BUSY,
-  FLASH_STATE_COMPLETE
-};
-
-volatile uint8_t _fl_state = FLASH_STATE_IDLE;
-
-void qspi_flash_complete (void)
-{
-  _fl_state = FLASH_STATE_COMPLETE;
-}
 
 //------------- IMPLEMENTATION -------------//
 // Callback invoked when received READ10 command.
@@ -68,24 +55,8 @@ int32_t tud_msc_read10_cb(uint8_t lun, uint32_t lba, uint32_t offset, void* buff
 {
   uint32_t addr = lba * CFG_TUD_MSC_BLOCK_SZ + offset;
 
-  switch ( _fl_state )
-  {
-    case FLASH_STATE_IDLE:
-      _fl_state = FLASH_STATE_BUSY;
-      flash_read(buffer, addr, bufsize);
-      return 0;    // data not ready
-
-    case FLASH_STATE_BUSY:
-      return 0;    // data not ready
-
-    case FLASH_STATE_COMPLETE:
-      _fl_state = FLASH_STATE_IDLE;
-      return bufsize;
-
-    default:
-      _fl_state = FLASH_STATE_IDLE;
-      return -1;
-  }
+  flash_read(buffer, addr, bufsize);
+  return bufsize;
 }
 
 // Callback invoked when received WRITE10 command.
@@ -124,16 +95,7 @@ void flash_flush (void)
   if ( _fl_addr == NO_CACHE ) return;
 
   TU_ASSERT(NRFX_SUCCESS == nrfx_qspi_erase(NRF_QSPI_ERASE_LEN_4KB, _fl_addr),);
-  while ( _fl_state != FLASH_STATE_COMPLETE )
-  {
-  }
-  _fl_state = FLASH_STATE_IDLE;
-
   TU_ASSERT(NRFX_SUCCESS == nrfx_qspi_write(_fl_buf, FLASH_PAGE_SIZE, _fl_addr),);
-  while ( _fl_state != FLASH_STATE_COMPLETE )
-  {
-  }
-  _fl_state = FLASH_STATE_IDLE;
 
   _fl_addr = NO_CACHE;
 }