diff --git a/lib/lwip/src/include/lwip/sio.h b/lib/lwip/src/include/lwip/sio.h
new file mode 100644
index 0000000..8a37aa3
--- /dev/null
+++ b/lib/lwip/src/include/lwip/sio.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * All rights reserved. 
+ * 
+ * Redistribution and use in source and binary forms, with or without modification, 
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission. 
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ */
+
+/*
+ * This is the interface to the platform specific serial IO module
+ * It needs to be implemented by those platforms which need SLIP or PPP
+ */
+
+#include "arch/cc.h"
+
+#ifndef __sio_fd_t_defined
+typedef void * sio_fd_t;
+#endif
+
+#ifndef sio_open
+sio_fd_t sio_open(u8_t);
+#endif
+
+#ifndef sio_send
+void sio_send(u8_t, sio_fd_t);
+#endif
+
+#ifndef sio_recv
+u8_t sio_recv(sio_fd_t);
+#endif
+
+#ifndef sio_read
+u32_t sio_read(sio_fd_t, u8_t *, u32_t);
+#endif
+
+#ifndef sio_write
+u32_t sio_write(sio_fd_t, u8_t *, u32_t);
+#endif
+
+#ifndef sio_read_abort
+void sio_read_abort(sio_fd_t);
+#endif