diff --git a/uc/Makefile b/uc/Makefile
index 79913d3..07c21b3 100755
--- a/uc/Makefile
+++ b/uc/Makefile
@@ -86,13 +86,15 @@ F_CPU	= 1000000
 # make TYPE= xxxx SENSOR0=yyyy ...
 #
 TYPE = 2301
+METERCONST = 7091
+MUXN = 0
 #
 SENSOR0 = 0123456789abcdef0123456789abcde0
 SENSOR1 = 0123456789abcdef0123456789abcde1
 SENSOR2 = 0123456789abcdef0123456789abcde2
 SENSOR3 = 0123456789abcdef0123456789abcde3
 #
-CEXTRA = -D TYPE=$(TYPE) -D 'SENSOR0="$(SENSOR0)"' -D 'SENSOR1="$(SENSOR1)"' -D 'SENSOR2="$(SENSOR2)"' -D 'SENSOR3="$(SENSOR3)"'
+CEXTRA = -D TYPE=$(TYPE) -D METERCONST=$(METERCONST) -D MUXN=$(MUXN) -D 'SENSOR0="$(SENSOR0)"' -D 'SENSOR1="$(SENSOR1)"' -D 'SENSOR2="$(SENSOR2)"' -D 'SENSOR3="$(SENSOR3)"'
 #####################################################################################
 
 #####################################################################################
diff --git a/uc/main.h b/uc/main.h
index 1d58be2..c478a08 100644
--- a/uc/main.h
+++ b/uc/main.h
@@ -40,36 +40,37 @@
   #define TYPE 2301
 #endif
 
+#ifndef METERCONST
+  #if TYPE == 2201   // 220V - 1-phase @ 488.28Hz sampling rate
+    #define METERCONST 6783
+    #define MUXN 0
+    #warning "220V - 1-phase selected. METERCONST set to 6783"
 
-#if TYPE == 2201   // 220V - 1-phase @ 488.28Hz sampling rate
-  #define METERCONST 6783
-  #define MUXN 0
-  #warning "220V - 1-phase selected. METERCONST set to 6783"
+  #elif TYPE == 2203 // 220V - 3-phase @ 488.28Hz sampling rate
+    #define METERCONST 6721
+    #define MUXN 1
+    #warning "220V - 3-phase selected. METERCONST set to 6721"
 
-#elif TYPE == 2203 // 220V - 3-phase @ 488.28Hz sampling rate
-  #define METERCONST 6721
-  #define MUXN 1
-  #warning "220V - 3-phase selected. METERCONST set to 6721"
+  #elif TYPE == 2301   // 230V - 1-phase @ 488.28Hz sampling rate
+    #define METERCONST 7091
+    #define MUXN 0
+    #warning "230V - 1-phase selected. METERCONST set to 7091"
 
-#elif TYPE == 2301   // 230V - 1-phase @ 488.28Hz sampling rate
-  #define METERCONST 7091
-  #define MUXN 0
-  #warning "230V - 1-phase selected. METERCONST set to 7091"
+  #elif TYPE == 2303 // 230V - 3-phase @ 488.28Hz sampling rate
+    #define METERCONST 7026
+    #define MUXN 1
+    #warning "230V - 3-phase selected. METERCONST set to 7026"
 
-#elif TYPE == 2303 // 230V - 3-phase @ 488.28Hz sampling rate
-  #define METERCONST 7026
-  #define MUXN 1
-  #warning "230V - 3-phase selected. METERCONST set to 7026"
+  #elif TYPE == 2401 // 240V - 1-phase @ 488.28Hz sampling rate
+    #define METERCONST 7399
+    #define MUXN 0
+    #warning "240V - 1-phase selected. METERCONST set to 7399"
 
-#elif TYPE == 2401 // 240V - 1-phase @ 488.28Hz sampling rate
-  #define METERCONST 7399
-  #define MUXN 0
-  #warning "240V - 1-phase selected. METERCONST set to 7399"
-
-#elif TYPE == 2403 // 240V - 3-phase @ 488.28Hz sampling rate
-  #define METERCONST 7331
-  #define MUXN 1
-  #warning "240V - 3-phase selected. METERCONST set to 7331"
+  #elif TYPE == 2403 // 240V - 3-phase @ 488.28Hz sampling rate
+    #define METERCONST 7331
+    #define MUXN 1
+    #warning "240V - 3-phase selected. METERCONST set to 7331"
+  #endif
 #endif
 
 #define START 0