+#define BUFFER_LEN 12
+
+void sci_init();
+void msg_clr();
+void send_packet();
+void send_ack();
+void send_nack();
+#define wait_for_tx_free() do { } while(0)
+
+extern char sci_tx_buf[BUFFER_LEN];
+extern volatile char sci_rx_buf[BUFFER_LEN];
+extern volatile u8 sci_have_packet;
+