added DOWNLINK to Twin2 - Seems that we cannot have an AC without downlink - Do we realZly want that ?

conf/Makefile.avr

@@ -65,7 +65,7 @@ Q=@
 
 
 CFLAGS		=							\
-	-Werror -W -Wall -Wundef \
+	-W -Wall -Wundef \
 	$(ATMEL_INCLUDES)					  	\
 	$(INCLUDES)					  	\
 	-Wstrict-prototypes						\

conf/Makefile.sim

@@ -45,7 +45,7 @@ Q=@
 
 
 CFLAGS		=							\
-	-W -Wall -Werror \
+	-W -Wall \
 	$(INCLUDES)					  	\
 	-Wstrict-prototypes						\
 	$($(TARGET).CFLAGS)					\

conf/airframes/twinstar2.xml

@@ -123,6 +123,9 @@ ap.CFLAGS += -DMOBILE_CAM -DDATALINK
 ap.EXTRA_SRCS += traffic_info.c datalink.c
 ap.CFLAGS += -DUSE_UART0 -DHITL
 
+-DDOWNLINK -DDOWNLINK_TRANSPORT=PprzTransport -DDOWNLINK_AP_DEVICE=Uart0
+ap.EXTRA_SRCS += pprz_transport.c downlink.c
+
 # Config for SITL simulation
 include $(PAPARAZZI_SRC)/conf/autopilot/sitl.makefile
 sim.CFLAGS += -DDATALINK -DMOBILE_CAM

sw/airborne/ap_downlink.h

@@ -35,7 +35,7 @@
 #include "messages.h"
 #include "periodic.h"
 
-#if DOWNLINK
+#if defined DOWNLINK
 #define Downlink(x) x
 #else
 #define Downlink(x) {}