diff --git a/src/portable/nuvoton/nuc120/dcd_nuc120.c b/src/portable/nuvoton/nuc120/dcd_nuc120.c
index 4e1db24a..ba593ba0 100644
--- a/src/portable/nuvoton/nuc120/dcd_nuc120.c
+++ b/src/portable/nuvoton/nuc120/dcd_nuc120.c
@@ -430,4 +430,16 @@ void dcd_isr(uint8_t rhport)
   USBD_IRQHandler();
 }
 
+void dcd_disconnect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_detach();
+}
+
+void dcd_connect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_attach();
+}
+
 #endif
diff --git a/src/portable/nuvoton/nuc121/dcd_nuc121.c b/src/portable/nuvoton/nuc121/dcd_nuc121.c
index 25d723d9..e7cb3dcd 100644
--- a/src/portable/nuvoton/nuc121/dcd_nuc121.c
+++ b/src/portable/nuvoton/nuc121/dcd_nuc121.c
@@ -446,4 +446,16 @@ void dcd_isr(uint8_t rhport)
   USBD_IRQHandler();
 }
 
+void dcd_disconnect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_detach();
+}
+
+void dcd_connect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_attach();
+}
+
 #endif
diff --git a/src/portable/nuvoton/nuc505/dcd_nuc505.c b/src/portable/nuvoton/nuc505/dcd_nuc505.c
index 8457e686..de842eeb 100644
--- a/src/portable/nuvoton/nuc505/dcd_nuc505.c
+++ b/src/portable/nuvoton/nuc505/dcd_nuc505.c
@@ -126,6 +126,11 @@ static void usb_attach(void)
   USBD->PHYCTL |= USBD_PHYCTL_DPPUEN_Msk;
 }
 
+static void usb_detach(void)
+{
+  USBD->PHYCTL &= ~USBD_PHYCTL_DPPUEN_Msk;
+}
+
 static void usb_control_send_zlp(void)
 {
   USBD->CEPINTSTS = USBD_CEPINTSTS_STSDONEIF_Msk;
@@ -647,4 +652,16 @@ void dcd_isr(uint8_t rhport)
   USBD_IRQHandler();
 }
 
+void dcd_disconnect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_detach();
+}
+
+void dcd_connect(uint8_t rhport)
+{
+  (void) rhport;
+  usb_attach();
+}
+
 #endif