Merge pull request #74 from XPila/MK3

setup second serial port only in case it is selected

Firmware/Configuration.h

@@ -9,7 +9,7 @@
 
 // Firmware version
 #define FW_version "3.0.12-RC2"
-#define FW_build   103
+#define FW_build   104
 #define FW_version_build FW_version " b" STR(FW_build)
 
 

Firmware/MarlinSerial.cpp

@@ -23,7 +23,7 @@
 #include "Marlin.h"
 #include "MarlinSerial.h"
 
-int selectedSerialPort = 0; 
+uint8_t selectedSerialPort = 0;
 
 #ifndef AT90USB
 // this next line disables the entire HardwareSerial.cpp, 
@@ -58,23 +58,23 @@ FORCE_INLINE void store_char(unsigned char c)
       // Test for a framing error.
       if (M_UCSRxA & (1<<M_FEx)) {
           // Characters received with the framing errors will be ignored.
-          // The temporary variable "c" was made volatile, so the compiler does not optimize this out.
-          volatile unsigned char c = M_UDRx;
+          // Dummy register read (discard)
+          (void)(*(char *)M_UDRx);
       } else {
           // Read the input register.
           unsigned char c = M_UDRx;
           store_char(c);
       }
   }
-  
+#ifndef SNMM
   SIGNAL(USART2_RX_vect)
   {
       if (selectedSerialPort == 1) {
         // Test for a framing error.
         if (UCSR2A & (1<<FE2)) {
             // Characters received with the framing errors will be ignored.
-            // The temporary variable "c" was made volatile, so the compiler does not optimize this out.
-            volatile unsigned char c = UDR2;
+            // Dummy register read (discard)
+            (void)(*(char *)UDR2);
         } else {
             // Read the input register.
             unsigned char c = UDR2;
@@ -84,6 +84,7 @@ FORCE_INLINE void store_char(unsigned char c)
       }
   }
 #endif
+#endif
 
 // Constructors ////////////////////////////////////////////////////////////////
 
@@ -124,8 +125,9 @@ void MarlinSerial::begin(long baud)
   sbi(M_UCSRxB, M_TXENx);
   sbi(M_UCSRxB, M_RXCIEx);
   
+#ifndef SNMM
 
-// set up the second serial port
+  if (selectedSerialPort == 1) { //set up also the second serial port 
 	  if (useU2X) {
 		  UCSR2A = 1 << U2X2;
 		  baud_setting = (F_CPU / 4 / baud - 1) / 2;
@@ -141,6 +143,8 @@ void MarlinSerial::begin(long baud)
 	  sbi(UCSR2B, RXEN2);
 	  sbi(UCSR2B, TXEN2);
 	  sbi(UCSR2B, RXCIE2);	  
+  }
+#endif
 }
 
 void MarlinSerial::end()
@@ -149,9 +153,11 @@ void MarlinSerial::end()
   cbi(M_UCSRxB, M_TXENx);
   cbi(M_UCSRxB, M_RXCIEx);
 
+#ifndef SNMM
   cbi(UCSR2B, RXEN2);
   cbi(UCSR2B, TXEN2);
   cbi(UCSR2B, RXCIE2);
+#endif
 }
 
 

Firmware/MarlinSerial.h

@@ -73,7 +73,7 @@
 // is the index of the location from which to read.
 #define RX_BUFFER_SIZE 128
 
-extern int selectedSerialPort;
+extern uint8_t selectedSerialPort;
 
 struct ring_buffer
 {