diff --git a/src/main.c b/src/main.c
index a2e51bf..7e1783d 100644
--- a/src/main.c
+++ b/src/main.c
@@ -12,6 +12,9 @@
 #include "ir_nec.h"
 
 /* global variables */
+#define INPUT_MAX 255 /* max length for user input string */
+char input[INPUT_MAX+2]; /* user input from USART */
+volatile uint8_t input_i = 0; /* user input index */
 volatile uint8_t pwr_ok; /* is power ok */
 volatile uint8_t fan; /* fan signal state, to measure tachometer */
 volatile uint8_t timer2_ovf = 0; /* to measure fan speed using timer 2 */
@@ -19,25 +22,34 @@ static const uint16_t TIMER2_PRESCALE[8] = {0,1,8,32,64,128,256,1024}; /* timer
 volatile uint16_t tachometer = 0; /* the tachometer time (from timer) */
 volatile uint8_t ir; /* IR signal state, to measure IR code */
 static const uint16_t TIMER1_PRESCALE[8] = {0,1,8,64,256,1024,0,0}; /* timer 1 CS1[2:0] values */
+volatile uint16_t ir_tick; /* number of counter ticks per millisecond */
 volatile uint8_t pulse = 0; /* pulse index within the burst */
 #define PULSE_MAX 128 /* maximum number of pulses to save */
 uint16_t burst[PULSE_MAX]; /* pulse times forming a burst (from timer) */
 
+/* flags, set in the interrupts and handled in the main program */
+volatile bool input_flag = false;
+volatile bool power_flag = false;
+
+/* UART receive interrupt */
+ISR(USART_RX_vect) {
+	input[input_i] = getchar(); /* save input */
+	input[input_i+1] = 0; /* always end the string */
+	if (input_i<INPUT_MAX) { /* next character, if space is available */
+		input_i++;
+	}
+	input_flag = true; /* set flag */
+}
 
 /* power ok interrupt */
 ISR(PCINT0_vect) { /* PCI0 Interrupt Vector for PCINT[7:0] */
 	if (pwr_ok!=(PINB&(1<<PWR_OK))) { /* did the PWR_OK pin state changed */
 		pwr_ok = PINB&(1<<PWR_OK); /* save new state */
-		if (pwr_ok) {
-			/* switch timer 2 on to start measuring the fan speed */
-			puts("power ok");
-		} else {
-			puts("power ko");
-		}
+		power_flag = true;
 	} else if (ir!=(PINB&(1<<IR))) { /* did the IR pin state changed */
 		ir = PINB&(1<<IR); /* save new state */
 		if (pulse>0) { /* save pulse, except the first */
-			burst[pulse-1] = TCNT1;
+			burst[pulse-1] = (TCNT1*1000UL)/ir_tick;
 			burst[pulse] = 0;
 		}
 		if (pulse<PULSE_MAX-1) { /* prepare to save next pulse */
@@ -69,7 +81,6 @@ ISR(TIMER2_OVF_vect) { /* timer 2 overflow interrupt vector */
 /* timer 1 interrupt used to measure IR pulse */
 ISR(TIMER1_COMPA_vect) { /* timer 1 OCR1A match interrupt vector */
 	if (pulse>0) {
-		pulse2time(burst,pulse-1);
 		time2nec(burst,pulse-1);
 		struct nec ir_data = nec2data(burst,pulse-1);
 		if (ir_data.valid) {
@@ -79,7 +90,6 @@ ISR(TIMER1_COMPA_vect) { /* timer 1 OCR1A match interrupt vector */
 				printf("IR addr: %u, command: %u\n",ir_data.address,ir_data.command);
 			}
 		}
-		OCR0A = ~OCR0A;
 		pulse = 0;
 	}
 }
@@ -140,8 +150,11 @@ static void ioinit(void)
 	/* clock/8 prescaler, offers most precision for 15ms (up to 28.5ms) */
 	TCCR1B |= (1<<CS11);
 	TCCR1B &= ~((1<<CS12)|(1<<CS10));
-	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10];
-	OCR1A = (uint32_t)(15*F_CPU)/(1000*prescale); /* set clear time to 15 ms (no IR toggle should be longer) */
+	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10]; /* timer 1 presacler */
+	if (0!=prescale) {
+		ir_tick = F_CPU/(1000*prescale); /* ticks per ms */
+		OCR1A = (uint32_t)(15*F_CPU)/(1000*prescale); /* set clear time to 15 ms (no IR toggle should be longer) */
+	}
 	TIFR1 &= ~(1<<OCF1A); /* clear timer 1 overflow interrupt flag */
 	TIMSK1 |= (1<<OCIE1A); /* enable timer 1 overflow interrupt */
 
@@ -159,35 +172,28 @@ static void ioinit(void)
 	sei(); /* enable interrupts */
 }
 
-/* convert burst to micro-seconds */
-static void pulse2time(uint16_t* burst, uint8_t pulses)
-{
-	uint16_t prescale = TIMER1_PRESCALE[(TCCR1B&((1<<CS12)|(1<<CS11)|(1<<CS10)))>>CS10]; /* timer 1 presacler */
-	uint16_t tick = F_CPU/(1000*prescale); /* ticks per ms */
-
-	if (0==prescale) {
-		return;
-	}
-	for (uint8_t i=0; i<pulse; i++) {
-		if (0==burst[i]) {
-			return;
-		}
-		burst[i] = (burst[i]*1000UL)/tick;
-	}
-}
-
 int main(void)
 {
 	ioinit(); /* initialize IOs */
 
-	char input;
+	uint8_t command_i = 0; /* command index */
+	char c = 0;
 
 	puts("LED dimmer up & running");
-	_delay_ms(1000);
-	while(1) {
-		input = getchar();
-		printf("%c\n", input);
-		switch (input) {
+	while (true) {
+		/* handle user input */
+		while (input_flag) {
+			while (command_i<input_i) {
+				c = input[command_i++];
+				putchar(c); /* echo back */
+			}
+			input_flag = false;
+		}
+	}
+{
+		_delay_ms(1000);
+		
+		switch (c) {
 			case 'l':
 				PIND |= (1<<LED);
 				printf("LED: ");
diff --git a/src/main.h b/src/main.h
index 2c602f5..1f92129 100644
--- a/src/main.h
+++ b/src/main.h
@@ -17,4 +17,3 @@
 #define CH2_5 PD7
 
 static void ioinit(void);
-static void pulse2time(uint16_t* burst, uint8_t pulses);
diff --git a/src/uart.c b/src/uart.c
index 34e5390..efbae80 100644
--- a/src/uart.c
+++ b/src/uart.c
@@ -20,8 +20,9 @@ void uart_init(void)
 #else
 	UCSR0A &= ~(1<<U2X0);
 #endif
-	UCSR0C = (1<<UCSZ01) | (1<<UCSZ00); /* 8N1-bit data */ 
-	UCSR0B = (1<<RXEN0) | (1<<TXEN0);   /* enable RX and TX */
+	UCSR0C = (1<<UCSZ01)|(1<<UCSZ00); /* 8N1 bit data */
+	UCSR0B = (1<<RXEN0)|(1<<TXEN0);   /* enable RX and TX */
+	UCSR0B |= (1<<RXCIE0); /* enable RX complete interrupt */
 }
 
 void uart_putchar(char c, FILE *stream)