Also check the DTR value, when deciding to drop data.

Author: ghent360

Diff for: cores/arduino/stm32/usb/cdc/usbd_cdc_if.c

@@ -245,9 +245,9 @@ void CDC_deInit(void)
   }
 }
 
-uint8_t CDC_connected()
+bool CDC_connected()
 {
-  return hUSBD_Device_CDC.dev_state == USBD_STATE_CONFIGURED;
+  return hUSBD_Device_CDC.dev_state == USBD_STATE_CONFIGURED && lineState;
 }
 
 void CDC_continue_transmit(void)

Diff for: cores/arduino/stm32/usb/cdc/usbd_cdc_if.h

@@ -50,7 +50,7 @@ void CDC_continue_transmit(void);
 void CDC_resume_receive(void);
 void CDC_init(void);
 void CDC_deInit(void);
-uint8_t CDC_connected();
+bool CDC_connected();
 
 #ifdef __cplusplus
 }