diff --git a/uc/Makefile b/uc/Makefile
index 21f48e0..fb2d8ae 100755
--- a/uc/Makefile
+++ b/uc/Makefile
@@ -87,7 +87,6 @@ F_CPU	= 1000000
 #
 TYPE = 2301
 METERCONST = 7091
-POWERCONST = 12466
 #
 SENSOR0 = 0123456789abcdef0123456789abcde0
 SENSOR1 = 0123456789abcdef0123456789abcde1
diff --git a/uc/main.c b/uc/main.c
index 01671ae..6d28722 100644
--- a/uc/main.c
+++ b/uc/main.c
@@ -38,12 +38,13 @@
 #include <avr/wdt.h>
 
 // variable declarations
-volatile struct state aux[4] = {{false, false, START, 0, 0}, {false, false, START, 0, 244}, {false, false, START, 0, 0}, {false, false, START, 0, 0}};
+volatile struct state aux[4] = {{false, false, START, 0}, {false, false, START, 0}, {false, false, START, 0}, {false, false, START, 0}};
 
 volatile struct sensor EEMEM EEPROM_measurements[4] = {{SENSOR0, START}, {SENSOR1, START}, {SENSOR2, START}, {SENSOR3, START}};
 volatile struct sensor measurements[4];
 
 volatile uint8_t muxn = 0;
+volatile uint16_t timer = 0;
 
 // interrupt service routine for INT0
 ISR(INT0_vect) {
@@ -78,22 +79,26 @@ ISR(TIMER2_OVF_vect) {
   if (muxn < 2) {
     MacU16X16to32(aux[muxn].nano, METERCONST, ADC);
 
-    if (++aux[muxn].count > 487) {
-      aux[muxn].adc = ADC;
-      aux[muxn].toggle = true;
-      aux[muxn].count = 0;
-    }
-
-    if (aux[muxn].nano > 1000000000) {
+    if (aux[muxn].nano > WATT) {
        measurements[muxn].value++;
        aux[muxn].pulse = true;
-       aux[muxn].nano -= 1000000000;
+       aux[muxn].nano -= WATT;
+       aux[muxn].pulse_count++;
+    }
+
+    if (timer == SECOND) {
+      aux[muxn].nano_start = aux[muxn].nano_end;
+      aux[muxn].nano_end = aux[muxn].nano;
+      aux[muxn].pulse_count_final = aux[muxn].pulse_count;
+      aux[muxn].pulse_count = 0;
+      aux[muxn].power = true;
     }
   }
 
-  // rotate amongst the available ADC input channels (0 to 7)
+  // rotate the available ADC input channels (0 to 7)
   muxn++;
-  muxn &= 0x7;
+  if (!(muxn &= 0x7)) timer++;
+  if (timer > SECOND) timer = 0;
 
   // but only use ADC0 and 1
   if (muxn < 2) {
@@ -236,11 +241,14 @@ void send(uint8_t msg_type, const struct sensor *measurement, const struct state
   char message[49];
   uint32_t value = 0;
 
+  int32_t rest;
+  uint8_t pulse_count;
+
   switch (msg_type) {
   case PULSE:
     // blink the green LED
     PORTB |= (1<<PB5);
-    _delay_ms(50);
+    _delay_ms(20);
     PORTB &= ~(1<<PB5);
 
     cli();
@@ -252,11 +260,17 @@ void send(uint8_t msg_type, const struct sensor *measurement, const struct state
 
   case POWER:
     cli();
-    uint16_t adc = aux->adc;
+    rest = aux->nano_end - aux->nano_start;
+    pulse_count = aux->pulse_count_final;
     sei();
 
-    MacU16X16to32(value, adc, POWERCONST);
-    value /= 1000;
+    MacU16X16to32(value, (uint16_t)(labs(rest)/65536), 242);
+    value /= 1024;
+
+    if (rest >= 0)
+      value += pulse_count*3600;
+    else
+      value = pulse_count*3600 - value;
 
     strcpy(message, "pwr ");
     break;
@@ -283,9 +297,9 @@ void loop()
       aux[i].pulse = false;
     }
 
-    if (aux[i].toggle == true && i < 2) {
+    if (aux[i].power == true) {
       send(POWER, (const struct sensor *)&measurements[i], (const struct state *)&aux[i]);
-      aux[i].toggle = false;
+      aux[i].power = false;
     }  
   }
   wdt_reset();
diff --git a/uc/main.h b/uc/main.h
index d84cc7f..5ccb93f 100644
--- a/uc/main.h
+++ b/uc/main.h
@@ -23,6 +23,9 @@
 # define PULSE 0
 # define POWER 1
 
+# define WATT 1000000000
+# define SECOND 487 // rounded down from 488.28125 - 1
+
 #ifndef SENSOR0 
   #define SENSOR0 "0123456789abcdef0123456789abcde0"
 #endif
@@ -46,32 +49,26 @@
 #ifndef METERCONST
   #if TYPE == 2201   // 220V - 1-phase @ 488.28Hz sampling rate
     #define METERCONST 6783
-    #define POWERCONST 11925
     #warning "220V - 1-phase selected. METERCONST set to 6783"
 
   #elif TYPE == 2203 // 220V - 3-phase @ 488.28Hz sampling rate
     #define METERCONST 6721
-    #define POWERCONST 11816
     #warning "220V - 3-phase selected. METERCONST set to 6721"
 
   #elif TYPE == 2301 // 230V - 1-phase @ 488.28Hz sampling rate
     #define METERCONST 7091
-    #define POWERCONST 12466
     #warning "230V - 1-phase selected. METERCONST set to 7091"
 
   #elif TYPE == 2303 // 230V - 3-phase @ 488.28Hz sampling rate
     #define METERCONST 7026
-    #define POWERCONST 12352
     #warning "230V - 3-phase selected. METERCONST set to 7026"
 
   #elif TYPE == 2401 // 240V - 1-phase @ 488.28Hz sampling rate
     #define METERCONST 7399
-    #define POWERCONST 13007
     #warning "240V - 1-phase selected. METERCONST set to 7399"
 
   #elif TYPE == 2403 // 240V - 3-phase @ 488.28Hz sampling rate
     #define METERCONST 7331
-    #define POWERCONST 12888
     #warning "240V - 3-phase selected. METERCONST set to 7331"
   #endif
 #endif
@@ -121,7 +118,12 @@ struct state {
   boolean toggle;
   uint32_t nano;
   uint16_t adc;
-  uint16_t count;
+
+  boolean  power;
+  uint32_t nano_start;
+  uint32_t nano_end;
+  uint8_t  pulse_count;
+  uint8_t  pulse_count_final;
 };
 
 struct sensor {