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====== Introduction ======

This article describes asynchrous serial programming using signal handler.

== References ==
  * Serial Programming HOWTO : [[http://tldp.org/HOWTO/Serial-Programming-HOWTO/]]

== Hardware used : ==
  * A desktop PC.
  * Roboard RB-100 : [[http://www.roboard.com/RB-100.htm]]
  * Mini PCI VGA Card : [[http://www.icop.com.tw/pddetail.aspx?id=93&pid=4]]
  * 4 Go micro SD card plugged in the built-in micro-SD card reader.
  * An internet connection.

== Softwares : ==
  * Ubuntu 10.10 installed on both Roboard and desktop PC : [[http://www.ubuntu.com/]]
  * Package **build-essential** already installed on your Ubuntu operating system.

====== Asynchronous serial I/O library ======

The following code is very simple. There is just one function to initialize the serial communication.
Only serial port device, baudrate and if there is a parity checking can be set. Everything else is hard coded, supposing we use 8 bits of data, 1 stop bit and a prefix on parity error.
Then it results in a very simple header file **serialCom.h** :
<code>#ifndef _SERIALCOM_H_
#define _SERIALCOM_H_

#ifdef __cplusplus
extern "C"
{
#endif

#include <termios.h>

  /* Controls :  CS8      = 8 bits
   *             CREAD    = Enable reading */
#define SERIAL_CONTROL  (CS8 | CREAD)

  /* Input    :  PARMRK   = If IGNPAR is not set, prefix a character with a parity error  or
   framing  error  with  \377  \0 */
#define SERIAL_INPUT    PARMRK

  /* Handler type definition */
  typedef void
  (*serial_handler)(int status);

  /* Serial port initialization function */
  int
  serialConfiguration(serial_handler, const char* device, tcflag_t baudrate,
      char parity);

#ifdef __cplusplus
}
#endif

#endif
</code>

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