diff --git a/Makefile b/Makefile
index d594a6d..1ef4029 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 PRG            = lipo-charger
 OBJ            = lipo-charger.o
-MCU_TARGET     = atmega8
+MCU_TARGET     = attiny24
 OPTIMIZE       = -Os
 
 DEFS           =
@@ -47,5 +47,5 @@ bin:  $(PRG).bin
 	$(OBJCOPY) -j .text -j .data -O binary $< $@
 
 install: text
-	uisp -dprog=avr910 -dserial=/dev/ttyS0 -dspeed=115200 -dpart=M8 --erase --upload if=$(PRG).hex
-#	avrdude -p m8 -c butterfly -b 19200 -P /dev/ttyUSB0 -u -e -U flash:w:$(PRG).hex
+#	uisp -dprog=avr910 -dserial=/dev/ttyS0 -dspeed=115200 -dpart=M8 --erase --upload if=$(PRG).hex
+	avrdude -p t24 -c butterfly -b 115200 -P /dev/ttyUSB0 -u -e -U flash:w:$(PRG).hex
diff --git a/lipo-charger.c b/lipo-charger.c
index e34a427..816f398 100644
--- a/lipo-charger.c
+++ b/lipo-charger.c
@@ -22,37 +22,21 @@
 #define F_CPU 8000000
 #include <util/delay.h>
 
-#include <stdio.h>
+#define ADC_REF	PORTA0
+#define ADC_U	PORTA1
+#define ADC_IM	PORTA2
+#define ADC_IP	PORTA3
+#define SUMMER	PORTA7
 
-#define BAUDRATE 19200
-#define UART_CALC_BAUDRATE(baudRate) ((uint32_t)(F_CPU) / ((uint32_t)(baudRate)*16) -1)
+#define LEDRT	PORTB0
+#define LEDGN	PORTB1
+#define PWM	PORTB2
 
-/*
- * LCD:
- * - CS Chip Select
- * - RS Register Select
- * - RW Read/Write
- */
-#define RS		PORTB6
-#define CS		PORTB7
-#define RW		PORTD3
-#define LCD_D4		PORTD4
-#define LCD_D5		PORTD5
-#define LCD_D6		PORTD6
-#define LCD_D7		PORTD7
-#define LCD_DATA_MASK	((1<<LCD_D4) | (1<<LCD_D5) | (1<<LCD_D6) | (1<<LCD_D7))
+/* ADC_U vs GND: voltage with prescaler (12V -> 2V; 15mV -> 2.5mV/bit), ref 2.56V */
+#define CH_U	((1<<REFS0) | 0x01)
 
-/*
- * power supply:
- * - CH0 - voltage with prescaler (12V -> 2V; 15mV -> 2.5mV/bit)
- * - CH1 - current with (1A -> 1000mV; 2.5mA -> 2.5mV/bit)
- * - PWM - high-active output to buckconverter
- */
-#define CH0	PORTC0
-#define CH1	PORTC1
-#define PWM	PORTB1
-
-#define NOP	asm volatile ("nop")
+/* ADC_IP vs ADC_IM: current sense (1A -> 100mV; ??mA -> ?mV/bit), gain x20, ref 5V */
+#define CH_I	((0<<REFS0) | 0x31)
 
 #define MOD_WAITING	0x00
 #define MOD_CHARGING	0x01
@@ -60,173 +44,37 @@
 
 #define VOLTAGE_CONNECT	 9000
 #define VOLTAGE_CHARGE	12450
-#define CURRENT_CHARGE	16000
+#define CURRENT_CHARGE	17500
 #define CURRENT_READY	 2000
 #define VOLTAGE_REMOVE	 1000
 
-static void lcd_wait_busy(void)
-{
-	uint8_t status;
-
-	DDRD &= ~(LCD_DATA_MASK);
-	PORTD |= (1<<RW);
-
-	do {
-		PORTB |= (1<<CS);
-		NOP;
-		NOP;
-		status = (PIND & LCD_DATA_MASK);
-		PORTB &= ~(1<<CS);
-
-		PORTB |= (1<<CS);
-		NOP;
-		NOP;
-		status |= ((PIND & LCD_DATA_MASK) >> 4);
-		PORTB &= ~(1<<CS);
-
-	} while (status & 0x80);
-
-	DDRD |= LCD_DATA_MASK;
-	PORTD &= ~(1<<RW);
-}
-
-static void lcd_write_ctrl(uint8_t val)
-{
-	PORTD &= ~(LCD_DATA_MASK);
-	PORTD |= (val & 0xF0);
-
-	PORTB |= (1<<CS);
-	NOP;
-	NOP;
-	PORTB &= ~(1<<CS);
-
-	PORTD &= ~(LCD_DATA_MASK);
-	PORTD |= ((val<<4) & 0xF0);
-
-	PORTB |= (1<<CS);
-	NOP;
-	NOP;
-	PORTB &= ~(1<<CS);
-
-	lcd_wait_busy();
-}
-
-static void lcd_write_data(uint8_t val)
-{
-	PORTD &= ~(LCD_DATA_MASK);
-	PORTD |= (val & 0xF0);
-	PORTB |= (1<<RS);
-
-	PORTB |= (1<<CS);
-	NOP;
-	NOP;
-	PORTB &= ~(1<<CS);
-
-	PORTD &= ~(LCD_DATA_MASK);
-	PORTD |= ((val<<4) & 0xF0);
-
-	PORTB |= (1<<CS);
-	NOP;
-	NOP;
-	PORTB &= ~(1<<CS);
-
-	PORTB &= ~(1<<RS);
-
-	lcd_wait_busy();
-}
-
-/* heartbeat chars */
-static const uint8_t mychars[] = {
-	0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x00,
-	0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x00, 0x00,
-	0x00, 0x00, 0x00, 0x1f, 0x00, 0x00, 0x00, 0x00,
-	0x00, 0x10, 0x08, 0x04, 0x02, 0x01, 0x00, 0x00,
-};
-
-static void lcd_init(void)
-{
-	_delay_ms(25);
-
-	lcd_wait_busy();
-
-	/* 4bit, 2lines, 5x7 font */
-	lcd_write_ctrl(0x28);
-
-	/* display on, cursor off, blink off */
-	lcd_write_ctrl(0x0C);
-
-	/* cursor increments */
-	lcd_write_ctrl(0x06);
-
-	lcd_write_ctrl(0x40 | 0x00);
-
-	uint8_t i;
-	for (i = 0; i < sizeof(mychars); i++)
-		lcd_write_data(mychars[i]);
-
-	/* clear & home pos */
-	lcd_write_ctrl(0x01);
-}
-
-static int uart_putchar(char c, FILE *stream)
-{
-	if (c == '\n')
-		uart_putchar('\r', stream);
-
-	loop_until_bit_is_set(UCSRA, UDRE);
-	UDR = c;
-	return 0;
-}
-
-static int lcd_putchar(char c, FILE *stream)
-{
-	lcd_write_data(c);
-	return 0;
-}
-
-static FILE lcd = FDEV_SETUP_STREAM(lcd_putchar, NULL, _FDEV_SETUP_WRITE);
-static FILE log = FDEV_SETUP_STREAM(uart_putchar, NULL, _FDEV_SETUP_WRITE);
-
 static uint16_t voltage;
 static uint16_t current;
 
 ISR(ADC_vect)
 {
-	if (ADMUX & 0x01) {
+	if (ADMUX == CH_I) {
 		current = ADCW * 25;
-		ADMUX = CH0;
+		ADMUX = CH_U;
 
 	} else {
 		voltage = ADCW * 15;
-		ADMUX = CH1;
+		ADMUX = CH_I;
 	}
+}
+
+ISR(TIM1_OVF_vect)
+{
+	/* Come back in 1ms */
+	TCNT1 = 0xFFFF - 8000;
 
 	/* start ADC again */
 	ADCSRA |= (1<<ADSC);
-}
 
-static uint8_t lcd_update;
-static uint8_t mode = MOD_WAITING;
-static uint8_t pwm;
+	static uint8_t pwm;
+	static uint8_t mode = MOD_WAITING;
 
-ISR(TIMER0_OVF_vect)
-{
-	static uint8_t cnt;
-
-	/* Come back in 1ms */
-	TCNT0 = 0xFF - 125;
-
-	/* update LCD every 250ms */
-	cnt++;
-	if (cnt == 250) {
-		cnt = 0;
-		lcd_update = 1;
-	}
-
-	/*
-	 * charge with constant voltage of 12.45V
-	 * and a current limit of 1.6A
-	 */
+	/* charge with constant voltage and current limit */
 	if (mode == MOD_CHARGING) {
 		if (voltage < (VOLTAGE_CHARGE -25) && current < (CURRENT_CHARGE -500))
 			if (pwm < 0xff)
@@ -236,27 +84,71 @@ ISR(TIMER0_OVF_vect)
 			if (pwm > 0x00)
 				pwm--;
 
-		OCR1A = pwm;
-		TCCR1A |= (1<<COM1A1);
+		OCR0A = pwm;
+		TCCR0A |= (1<<COM1A1);
+
 	} else {
 		pwm = 0;
-		TCCR1A &= ~(1<<COM1A1);
+		TCCR0A &= ~(1<<COM1A1);
 	}
 
+	static uint16_t led_timer;
+	led_timer = (led_timer +1) & 0x3FF;
+
 	switch (mode) {
 	case MOD_WAITING:
+		/* green flashing, red off */
+		if (led_timer < 0x3F)
+			PORTB &= ~(1<<LEDGN);
+		else
+			PORTB |= (1<<LEDGN) | (1<<LEDRT);
+
+		PORTA |= (1<<SUMMER);
+
 		/* start charging when a voltage > 9V is detected (lipo connected) */
 		if (voltage > VOLTAGE_CONNECT)
 			mode = MOD_CHARGING;
+
 		break;
 
 	case MOD_CHARGING:
+		/* current limit */
+		if (voltage < (VOLTAGE_CHARGE -50)) {
+			/* green on, red fast blinking */
+			if (led_timer & 0x80)
+				PORTB &= ~((1<<LEDGN) | (1<<LEDRT));
+			else
+				PORTB |= (1<<LEDRT);
+
+		/* voltage limit */
+		} else {
+			/* green on, red slow blinking */
+			if (led_timer & 0x200)
+				PORTB &= ~((1<<LEDGN) | (1<<LEDRT));
+			else
+				PORTB |= (1<<LEDRT);
+		}
+
+		PORTA |= (1<<SUMMER);
+
 		/* end charging if voltage > 12.45V and current < 200mA */
 		if (voltage >= VOLTAGE_CHARGE && current < CURRENT_READY)
 			mode = MOD_READY;
 		break;
 
 	case MOD_READY:
+		/* green on, red flashing */
+		if (led_timer < 0x3F)
+			PORTB &= ~((1<<LEDGN) | (1<<LEDRT));
+		else
+			PORTB |= (1<<LEDRT);
+
+		/* beeping */
+		if (led_timer < 0x07)
+			PORTA &= ~(1<<SUMMER);
+		else
+			PORTA |= (1<<SUMMER);
+
 		/* wait for lipo disconnect */
 		if (voltage < VOLTAGE_REMOVE)
 			mode = MOD_WAITING;
@@ -266,89 +158,29 @@ ISR(TIMER0_OVF_vect)
 
 int main(void)
 {
-	DDRB = (1<<CS) | (1<<RS) | (1<<PWM);
-	DDRD = (LCD_DATA_MASK) | (1<<RW);
+	/* digital outputs */
+	DDRA = (1<<SUMMER);
+	DDRB = (1<<LEDGN) | (1<<LEDRT) | (1<<PWM);
 
-	/* Set baud rate 19200 */
-	UBRRH = (UART_CALC_BAUDRATE(BAUDRATE)>>8) & 0xFF;
-	UBRRL = (UART_CALC_BAUDRATE(BAUDRATE) & 0xFF);
+	/* analog inputs */
+	DIDR0 = (1<<ADC_REF) | (1<<ADC_U) | (1<<ADC_IM) | (1<<ADC_IP);
 
-	/* USART: rx/tx enable, 19200, 8n1 */
-	UCSRB = (1<<TXEN) | (1<<RXEN);
-	UCSRC = (1<<URSEL) | (1<<UCSZ1) | (1<<UCSZ0);
+	/* timer0: running with F_CPU, 8bit Fast PWM (32khz) */
+	TCCR0A = (1<<WGM00) | (1<<WGM01);
+	TCCR0B = (1<<CS00);
 
-	/* timer0: running with F_CPU/64 (125kHz) */
-	TCCR0 = (1<<CS01) | (1<<CS00);
+	/* timer1: running with F_CPU */
+	TCCR1B = (1<<CS00);
 
-	/* timer1: running with F_CPU, 8bit Phase Correct PWM (16kHz) */
-	TCCR1A = (1<<WGM10);
-	TCCR1B = (1<<CS10) | (1<<WGM12);
-
-	/* enable Timer0 OVF Interrupt */
-	TIMSK = (1<<TOIE0);
-
-	/* external 2.56V reference, channel 0 */
-	ADMUX = CH0;
+	/* enable iimer1 OVF Interrupt */
+	TIMSK1 = (1<<TOIE1);
 
 	/* enable ADC with interrupts, 125kHz clk */
+	ADMUX = CH_I;
 	ADCSRA = (1<<ADEN) | (1<<ADSC) | (1<<ADIE) | (1<<ADPS2) | (1<<ADPS1);
 
 	sei();
 
-	lcd_init();
-
-	uint8_t step = 0;
-	uint8_t hours = 0, minutes = 0, seconds = 0;
-
-	while (1) {
-		if (lcd_update) {
-			/* first line, first char */
-			lcd_write_ctrl(0x80 | 0x00);
-			fprintf(&lcd, "%2d.%03dV ", voltage / 1000, voltage % 1000);
-			fprintf(&lcd, "%1d.%04dA ", current / 10000, current % 10000);
-			fprintf(&lcd, "0x%02x", pwm);
-
-			step = (step +1) & 0x03;
-			if (step == 0 && mode == MOD_CHARGING) {
-				seconds++;
-				if (seconds == 60) {
-					seconds = 0;
-					minutes++;
-					if (minutes == 60) {
-						minutes = 0;
-						hours++;
-					}
-				}
-
-				fprintf(&log, "%02d:%02d:%02d %05d %05d %03d\n",
-					hours, minutes, seconds, voltage, current, pwm);
-			}
-
-			/* second line, first char */
-			lcd_write_ctrl(0x80 | 0x40);
-			fprintf(&lcd, "%02d:%02d:%02d ", hours, minutes, seconds);
-
-			switch (mode) {
-			case MOD_WAITING:
-				fprintf(&lcd, " waiting ");
-				hours = minutes = seconds = 0;
-				break;
-
-			case MOD_CHARGING:
-				fprintf(&lcd, " charging");
-				break;
-
-			case MOD_READY:
-				fprintf(&lcd, " ready   ");
-				break;
-			}
-
-			/* second line, last char */
-			lcd_write_ctrl(0x80 | 0x40 | 19);
-			lcd_write_data(step);
-
-			lcd_update = 0;
-		}
-	}
+	while (1);
 	return 0;
 }