diff --git a/src/Makefile b/src/Makefile
index 7fd88283b..233414ed4 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -157,6 +157,11 @@ PXX = NO
 # Values = NO, SERIAL, PPM
 DSM2 = NO
 
+# DSM/PPM TX caddy PCB (Gruvin)
+# For auto-switching switching between DSM2/X and Fr-Sky transmitter modules
+# Values = YES, NO
+TX_CADDY = NO
+
 #IR protocols (SILV / TRAC09 / PICZ / SWIFT)
 IRPROTOS = NO
 
@@ -662,6 +667,10 @@ ifeq ($(DSM2), PPM)
   CPPDEFS += -DDSM2 -DDSM2_PPM
 endif
 
+ifeq ($(TX_CADDY), YES)
+  CPPDEFS += -DTX_CADDY
+endif
+
 ifeq ($(IRPROTOS), YES)
   CPPDEFS += -DIRPROTOS
 endif
diff --git a/src/pulses_avr.cpp b/src/pulses_avr.cpp
index ba4cde6a3..65c998567 100644
--- a/src/pulses_avr.cpp
+++ b/src/pulses_avr.cpp
@@ -736,6 +736,13 @@ void setupPulses()
     PORTH |= 0x80; // PORTH:7 LOW->HIGH signals start of setupPulses()
 #endif
 
+#if defined (PCBGRUVIN9X) && defined(TX_CADDY)
+    if (required_protocol == PROTO_DSM2)
+      PORTH &= ~0x80;
+    else
+      PORTH |= 0x80;
+#endif
+
   if (s_pulses_paused)
     required_protocol = PROTO_NONE;