+#if HAS_SERIAL_3
+extern volatile __xdata struct ao_fifo ao_serial3_rx_fifo;
+extern volatile __xdata struct ao_fifo ao_serial3_tx_fifo;
+
+char
+ao_serial3_getchar(void);
+
+int
+_ao_serial3_pollchar(void);
+
+void
+ao_serial3_putchar(char c);
+
+void
+ao_serial3_drain(void);
+
+void
+ao_serial3_set_speed(uint8_t speed);
+#endif
+