+void display_buffer(byte *buf);
+
+// usbdev.c
+
+extern byte rx_packet[64];
+extern byte tx_packet[64];
+extern volatile byte rx_packet_state, tx_packet_state;
+
+void tx_packet_send(void);
+
+// bmp085.c
+
+extern s16 adjusted_temp;
+extern s16 adjusted_press;
+
+extern volatile byte *bmp_i2c_ptr;
+extern volatile byte bmp_i2c_len;
+extern volatile byte bmp_i2c_addr;
+
+void bmp_init(void);
+void bmp_step(void);