diff --git a/arduino_nano/main.c b/arduino_nano/main.c
index f2fc8ba..c8b14fa 100644
--- a/arduino_nano/main.c
+++ b/arduino_nano/main.c
@@ -46,10 +46,24 @@ void wdt_init(void)
 {
 	MCUSR = 0;
 	wdt_disable();
-
-	return;
 }
 
+/* enable watchdog with interrupt and system reset (modified wdt_enable) */
+#define wdt_set(value) \
+__asm__ __volatile__ ( \
+    "in __tmp_reg__,__SREG__" "\n\t" \
+    "cli" "\n\t" \
+    "wdr" "\n\t" \
+    "sts %0,%1" "\n\t" \
+    "out __SREG__,__tmp_reg__" "\n\t" \
+    "sts %0,%2" "\n\t" \
+    : /* no outputs */ \
+    : "M" (_SFR_MEM_ADDR(_WD_CONTROL_REG)), \
+    "r" (_BV(_WD_CHANGE_BIT) | _BV(WDE) | _BV(WDIE)), \
+    "r" ((uint8_t) ((value & 0x08 ? _WD_PS3_MASK : 0x00) | _BV(WDE)  | _BV(WDIE) | (value & 0x07)) ) \
+    : "r0"  \
+)
+
 /* initialize GPIO */
 void io_init(void)
 {
@@ -73,7 +87,7 @@ int main(void)
 {
 	io_init(); // initialize IOs
 	
-	printf(PSTR("welcome to the spar counter power meter monitor\n"));
+	//printf(PSTR("welcome to the spar counter power meter monitor\n"));
 	
 	/* configure nRF24 transceiver */
 	nrf24_set_rx_addr(conf.rx_addr); // set device receiving address
@@ -98,24 +112,12 @@ int main(void)
 	
 	bool action = false; // to know if we performed any king of action during which some other activity could have happened
 
-	/* start watchdog */
-/*
-	wdt_enable(WDTO_4S);
-	while (true);
-	WDTCSR = (1<<WDCE); // change settings
-	//WDTCSR = (0<<WDP3)|(1<<WDP2)|(1<<WDP1)|(1<<WDP0); // set time-out to 2s
-	WDTCSR = (1<<WDP3)|(0<<WDP2)|(0<<WDP1)|(1<<WDP0);
-	WDTCSR = (1<<WDCE); // change settings
-	WDTCSR = (1<<WDE)|(1<<WDIE); // enable interrupt than system reset mode
-	while (true);
-*/
-
 	while (true) { // endless loop for micro-controller
 		action = false; // new cycle of actions
-		if (watchdog) { // watchdog interrupt trigger. clear before system reset
-			WDTCSR = (1<<WDCE); // change settings
-			WDTCSR = (1<<WDE)|(1<<WDIE); // enable interrupt than system reset mode
-			watchdog = false;
+		if (watchdog) { // watchdog interrupt trigger. reset watchdog before system reset
+			wdt_set(WDTO_2S); // set to 4s (interrupt and reset mode)
+			sei(); // re-enable interrupts
+			watchdog = false; // wait for next reset
 		}
 		if (timer_seconds!=0 && timer_seconds==conf.request_period) {
 			action = true; // an action is performed