diff --git a/atusb/fw/Makefile b/atusb/fw/Makefile
index 6df8112..e1d0823 100644
--- a/atusb/fw/Makefile
+++ b/atusb/fw/Makefile
@@ -31,7 +31,7 @@ SIZE = $(AVR_PREFIX)size
 USB_ID = 20b7:1540
 
 USB_OBJS = usb.o atu2.o
-OBJS = atusb.o board.o sernum.o spi.o descr.o ep0.o $(USB_OBJS)
+OBJS = atusb.o board.o board_app.o sernum.o spi.o descr.o ep0.o $(USB_OBJS)
 BOOT_OBJS = boot.o board.o sernum.o spi.o flash.o dfu.o $(USB_OBJS)
 
 vpath %.c usb/
diff --git a/atusb/fw/board.c b/atusb/fw/board.c
index 7e1bd98..774eaac 100644
--- a/atusb/fw/board.c
+++ b/atusb/fw/board.c
@@ -1,5 +1,5 @@
 /*
- * fw/board.c - Board-specific functions
+ * fw/board.c - Board-specific functions (for boot loader and application)
  *
  * Written 2011 by Werner Almesberger
  * Copyright 2011 Werner Almesberger
@@ -29,9 +29,6 @@
 uint8_t board_sernum[42] = { 42, USB_DT_STRING };
 
 
-static uint32_t timer_h = 0;	/* 2^(16+32) / 8 MHz = ~1.1 years */
-
-
 static void set_clkm(void)
 {
 	/* switch CLKM to 8 MHz */
@@ -84,25 +81,6 @@ void reset_rf(void)
 }
 
 
-void reset_cpu(void)
-{
-	WDTCSR = 1 << WDE;
-}
-
-
-uint8_t read_irq(void)
-{
-	return PIN(IRQ_RF);
-}
-
-
-void slp_tr(void)
-{
-	SET(SLP_TR);
-	CLR(SLP_TR);
-}
-
-
 void led(int on)
 {
 	if (on)
@@ -124,36 +102,6 @@ void panic(void)
 }
 
 
-void timer_poll(void)
-{
-	if (!(TIFR1 & (1 << TOV1)))
-		return;
-	TIFR1 = 1 << TOV1;
-	timer_h++;
-}
-
-
-uint64_t timer_read(void)
-{
-	uint32_t high;
-	uint8_t low, mid;
-
-	do {
-		timer_poll();
-		high = timer_h;
-		low = TCNT1L;
-		mid = TCNT1H;
-	}
-	while (TIFR1 & (1 << TOV1));
-
-	/*
-	 * We need all these casts because the intermediate results are handled
-	 * as if they were signed and thus get sign-expanded. Sounds wrong-ish.
-	 */
-	return (uint64_t) high << 16 | (uint64_t) mid << 8 | (uint64_t) low;
-}
-
-
 static char hex(uint8_t nibble)
 {
 	return nibble < 10 ? '0'+nibble : 'a'+nibble-10;
@@ -173,53 +121,6 @@ static void get_sernum(void)
 }
 
 
-int gpio(uint8_t port, uint8_t data, uint8_t dir, uint8_t mask, uint8_t *res)
-{
-	switch (port) {
-	case 1:
-		DDRB = (DDRB & ~mask) | dir;
-		PORTB = (PORTB & ~mask) | data;
-		break;
-	case 2:
-		DDRC = (DDRC & ~mask) | dir;
-		PORTC = (PORTC & ~mask) | data;
-		break;
-	case 3:
-		DDRD = (DDRD & ~mask) | dir;
-		PORTD = (PORTD & ~mask) | data;
-		break;
-	default:
-		return 0;
-	}
-
-	/* disable the UART so that we can meddle with these pins as well. */
-	UCSR1B = 0;
-	_delay_ms(1);
-
-	switch (port) {
-	case 1:
-		res[0] = PINB;
-		res[1] = PORTB;
-		res[2] = DDRB;
-		break;
-	case 2:
-		res[0] = PINC;
-		res[1] = PORTC;
-		res[2] = DDRC;
-		break;
-	case 3:
-		res[0] = PIND;
-		res[1] = PORTD;
-		res[2] = DDRD;
-		break;
-	}
-
-	spi_init();
-
-	return 1;
-}
-
-
 void board_init(void)
 {
 	/* Disable the watchdog timer */
diff --git a/atusb/fw/board_app.c b/atusb/fw/board_app.c
new file mode 100644
index 0000000..168ebe3
--- /dev/null
+++ b/atusb/fw/board_app.c
@@ -0,0 +1,125 @@
+/*
+ * fw/board_app.c - Board-specific functions (for the application)
+ *
+ * Written 2011 by Werner Almesberger
+ * Copyright 2011 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include <stdint.h>
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/boot.h>
+
+#define F_CPU   8000000UL
+#include <util/delay.h>
+
+#include "usb.h"
+#include "at86rf230.h"
+#include "board.h"
+#include "spi.h"
+
+
+static uint32_t timer_h = 0;	/* 2^(16+32) / 8 MHz = ~1.1 years */
+
+
+void reset_cpu(void)
+{
+	WDTCSR = 1 << WDE;
+}
+
+
+uint8_t read_irq(void)
+{
+	return PIN(IRQ_RF);
+}
+
+
+void slp_tr(void)
+{
+	SET(SLP_TR);
+	CLR(SLP_TR);
+}
+
+
+void timer_poll(void)
+{
+	if (!(TIFR1 & (1 << TOV1)))
+		return;
+	TIFR1 = 1 << TOV1;
+	timer_h++;
+}
+
+
+uint64_t timer_read(void)
+{
+	uint32_t high;
+	uint8_t low, mid;
+
+	do {
+		timer_poll();
+		high = timer_h;
+		low = TCNT1L;
+		mid = TCNT1H;
+	}
+	while (TIFR1 & (1 << TOV1));
+
+	/*
+	 * We need all these casts because the intermediate results are handled
+	 * as if they were signed and thus get sign-expanded. Sounds wrong-ish.
+	 */
+	return (uint64_t) high << 16 | (uint64_t) mid << 8 | (uint64_t) low;
+}
+
+
+int gpio(uint8_t port, uint8_t data, uint8_t dir, uint8_t mask, uint8_t *res)
+{
+	switch (port) {
+	case 1:
+		DDRB = (DDRB & ~mask) | dir;
+		PORTB = (PORTB & ~mask) | data;
+		break;
+	case 2:
+		DDRC = (DDRC & ~mask) | dir;
+		PORTC = (PORTC & ~mask) | data;
+		break;
+	case 3:
+		DDRD = (DDRD & ~mask) | dir;
+		PORTD = (PORTD & ~mask) | data;
+		break;
+	default:
+		return 0;
+	}
+
+	/* disable the UART so that we can meddle with these pins as well. */
+	UCSR1B = 0;
+	_delay_ms(1);
+
+	switch (port) {
+	case 1:
+		res[0] = PINB;
+		res[1] = PORTB;
+		res[2] = DDRB;
+		break;
+	case 2:
+		res[0] = PINC;
+		res[1] = PORTC;
+		res[2] = DDRC;
+		break;
+	case 3:
+		res[0] = PIND;
+		res[1] = PORTD;
+		res[2] = DDRD;
+		break;
+	}
+
+	spi_init();
+
+	return 1;
+}