1 files changed, 15 insertions, 3 deletions
diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index 49a3796..1b1fa71 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -50,6 +50,10 @@ struct ring_buffer
   volatile int tail;
 };
 
+#if defined(USBCON)
+  ring_buffer rx_buffer = { { 0 }, 0, 0};
+  ring_buffer tx_buffer = { { 0 }, 0, 0};
+#endif
 #if defined(UBRRH) || defined(UBRR0H)
   ring_buffer rx_buffer  =  { { 0 }, 0, 0 };
   ring_buffer tx_buffer  =  { { 0 }, 0, 0 };
@@ -81,10 +85,13 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
   }
 }
 
+#if !defined(USART0_RX_vect) && defined(USART1_RX_vect)
+// do nothing - on the 32u4 the first USART is USART1
+#else
 #if !defined(USART_RX_vect) && !defined(SIG_USART0_RECV) && \
     !defined(SIG_UART0_RECV) && !defined(USART0_RX_vect) && \
 	!defined(SIG_UART_RECV)
-  #error Don't know what the Data Received vector is called for the first UART
+  #error "Don't know what the Data Received vector is called for the first UART"
 #else
   void serialEvent() __attribute__((weak));
   void serialEvent() {}
@@ -111,6 +118,7 @@ inline void store_char(unsigned char c, ring_buffer *buffer)
     store_char(c, &rx_buffer);
   }
 #endif
+#endif
 
 #if defined(USART1_RX_vect)
   void serialEvent1() __attribute__((weak));
@@ -168,8 +176,11 @@ void serialEventRun(void)
 }
 
 
+#if !defined(USART0_UDRE_vect) && defined(USART1_UDRE_vect)
+// do nothing - on the 32u4 the first USART is USART1
+#else
 #if !defined(UART0_UDRE_vect) && !defined(UART_UDRE_vect) && !defined(USART0_UDRE_vect) && !defined(USART_UDRE_vect)
-  #error Don't know what the Data Register Empty vector is called for the first UART
+  #error "Don't know what the Data Register Empty vector is called for the first UART"
 #else
 #if defined(UART0_UDRE_vect)
 ISR(UART0_UDRE_vect)
@@ -204,6 +215,7 @@ ISR(USART_UDRE_vect)
   }
 }
 #endif
+#endif
 
 #ifdef USART1_UDRE_vect
 ISR(USART1_UDRE_vect)
@@ -393,7 +405,7 @@ size_t HardwareSerial::write(uint8_t c)
 #elif defined(UBRR0H) && defined(UBRR0L)
   HardwareSerial Serial(&rx_buffer, &tx_buffer, &UBRR0H, &UBRR0L, &UCSR0A, &UCSR0B, &UDR0, RXEN0, TXEN0, RXCIE0, UDRIE0, U2X0);
 #elif defined(USBCON)
-  #warning no serial port defined  (port 0)
+  // do nothing - Serial object and buffers are initialized in CDC code
 #else
   #error no serial port defined  (port 0)
 #endif