diff --git a/IO.h b/IO.h
index b8e5a7e..c50f08f 100644
--- a/IO.h
+++ b/IO.h
@@ -48,9 +48,17 @@
 #define SCAN_PAUSE 20000
 
 #if defined(DUPLEX)
-#define CAL_DLY_LOOP 96100U
+#if defined(STM32_USB_HOST)
+#define CAL_DLY_LOOP 98950U
 #else
-#define CAL_DLY_LOOP 106000U
+#define CAL_DLY_LOOP 105100U
+#endif
+#else
+#if defined(STM32_USB_HOST)
+#define CAL_DLY_LOOP 110850U
+#else
+#define CAL_DLY_LOOP 114350U
+#endif
 #endif
 
 extern uint32_t  m_frequency_rx;