APM: allow serial buffer size to be configured

very useful for packet forwarding setups

ArduPlane/Makefile

@@ -44,10 +44,10 @@ etags:
 	cd .. && etags -f ArduPlane/TAGS --langmap=C++:.pde.cpp.h $$(git ls-files ArduPlane libraries)
 
 obc:
-	make -f Makefile EXTRAFLAGS="-DCONFIG_APM_HARDWARE=APM_HARDWARE_APM2 -DOBC_FAILSAFE=ENABLED -DTELEMETRY_UART2=ENABLED"
+	make -f Makefile EXTRAFLAGS="-DCONFIG_APM_HARDWARE=APM_HARDWARE_APM2 -DOBC_FAILSAFE=ENABLED -DTELEMETRY_UART2=ENABLED -DSERIAL_BUFSIZE=512"
 
 obc-sitl:
-	make -f ../libraries/Desktop/Makefile.desktop EXTRAFLAGS="-DOBC_FAILSAFE=ENABLED"
+	make -f ../libraries/Desktop/Makefile.desktop EXTRAFLAGS="-DOBC_FAILSAFE=ENABLED -DSERIAL_BUFSIZE=512"
 
 sitl-newcontrollers:
 	make -f ../libraries/Desktop/Makefile.desktop EXTRAFLAGS="-DAPM_CONTROL=ENABLED"

ArduPlane/config.h

@@ -849,3 +849,7 @@
 #ifndef APM_CONTROL
 # define APM_CONTROL DISABLED
 #endif
+
+#ifndef SERIAL_BUFSIZE
+# define SERIAL_BUFSIZE 256
+#endif

ArduPlane/system.pde

@@ -81,7 +81,7 @@ static void init_ardupilot()
     // The console port buffers are defined to be sufficiently large to support
     // the MAVLink protocol efficiently
     //
-    Serial.begin(SERIAL0_BAUD, 128, 256);
+    Serial.begin(SERIAL0_BAUD, 128, SERIAL_BUFSIZE);
 
     // GPS serial port.
     //
@@ -137,7 +137,7 @@ static void init_ardupilot()
     }
 #else
     // we have a 2nd serial port for telemetry
-    Serial3.begin(map_baudrate(g.serial3_baud, SERIAL3_BAUD), 128, 256);
+    Serial3.begin(map_baudrate(g.serial3_baud, SERIAL3_BAUD), 128, SERIAL_BUFSIZE);
     gcs3.init(&Serial3);
 #endif