diff --git a/hw/mcu/nxp/lpc43xx/hal/dcd_lpc43xx.c b/hw/mcu/nxp/lpc43xx/hal/dcd_lpc43xx.c
index a7ec01d79..cb6311287 100644
--- a/hw/mcu/nxp/lpc43xx/hal/dcd_lpc43xx.c
+++ b/hw/mcu/nxp/lpc43xx/hal/dcd_lpc43xx.c
@@ -252,7 +252,7 @@ bool hal_dcd_init(uint8_t coreid)
 
   lpc_usb->ENDPOINTLISTADDR = (uint32_t) p_dcd->qhd; // Endpoint List Address has to be 2K alignment
   lpc_usb->USBSTS_D  = lpc_usb->USBSTS_D;
-  lpc_usb->USBINTR_D = INT_MASK_USB | INT_MASK_ERROR | INT_MASK_PORT_CHANGE | INT_MASK_RESET | INT_MASK_SUSPEND /*| INT_MASK_SOF */;
+  lpc_usb->USBINTR_D = INT_MASK_USB | INT_MASK_ERROR | INT_MASK_PORT_CHANGE | INT_MASK_RESET | INT_MASK_SUSPEND | INT_MASK_SOF;
 
   lpc_usb->USBCMD_D &= ~0x00FF0000; // Interrupt Threshold Interval = 0
   lpc_usb->USBCMD_D |= BIT_(0); // connect
@@ -595,7 +595,7 @@ void hal_dcd_isr(uint8_t coreid)
 
   if (int_status & INT_MASK_SOF)
   {
-//    hal_dcd_bus_event(coreid, USBD_BUS_EVENT_SOF);
+    hal_dcd_bus_event(coreid, USBD_BUS_EVENT_SOF);
   }
 
   if (int_status & INT_MASK_NAK) {}
diff --git a/tinyusb/class/cdc/cdc_device.c b/tinyusb/class/cdc/cdc_device.c
index 4e9a22539..0b83457b5 100644
--- a/tinyusb/class/cdc/cdc_device.c
+++ b/tinyusb/class/cdc/cdc_device.c
@@ -270,6 +270,8 @@ tusb_error_t cdcd_xfer_cb(endpoint_handle_t edpt_hdl, tusb_event_t event, uint32
 
 void cdcd_sof(uint8_t coreid)
 {
+  if ( !tud_cdc_connected(coreid) ) return;
+
   endpoint_handle_t ep = cdcd_data[coreid].edpt_hdl[CDC_PIPE_DATA_IN];
 
   if ( !dcd_pipe_is_busy( ep ) )
@@ -280,16 +282,16 @@ void cdcd_sof(uint8_t coreid)
   }
 }
 
-uint32_t tud_cdc_available(uint8_t coreid)
-{
-  return fifo_count(&_rx_ff);
-}
-
 bool tud_cdc_connected(uint8_t coreid)
 {
   return cdcd_data[coreid].connected;
 }
 
+uint32_t tud_cdc_available(uint8_t coreid)
+{
+  return fifo_count(&_rx_ff);
+}
+
 int tud_cdc_read_char(uint8_t coreid)
 {
   uint8_t ch;