从现在开始分析BACnet协议栈了，版本号是bacnet-stack-0.7.1。目录是bacnet-stack-0.7.1\ports\linux\rs485.c
rs485.c文件主要要解决在物理层发送和接收数据的作用。不同的开发板需要移植该文件。
#include
#include
#include
#include
#include
#include
#include
/* Linux includes */
#include
#include
#include
#include
#include
#include
/* Local includes */
#include "mstp.h"
#include "rs485.h"
#include "fifo.h"
#include
#include
/* Posix serial programming reference:
/~mike/serial/serial.html */
/* Use ionice wrapper to improve serial performance:
$ sudo ionice -c 1 -n 0 ./bin/bacserv 12345
*/
/* handle returned from open() */
static int RS485_Handle = -1;
/* baudrate settings are defined in
included by
static unsigned int RS485_Baud = B38400;//波特率选择38400 bps
/* serial port name, /dev/ttyS0,
/dev/ttyUSB0 for USB->RS485 from B&B Electronics USOPTL4 */
static char *RS485_Port_Name = "/dev/ttyUSB0"; /*系统默认是通过USB转485的，根据需要设置，若你的开发板用485接口，则用static char *RS485_Port_Name = "/dev/ttyS0";代替*/
/* some terminal I/O have RS-485 specific functionality */
#ifndef RS485MOD
#define RS485MOD 0
#endif
/* serial I/O settings */
static struct termios RS485_oldtio;
/* Ring buffer for incoming bytes, in order to speed up the receiving. */ static FIFO_BUFFER Rx_FIFO;
/* buffer size needs to be a power of 2 */
static uint8_t Rx_Buffer[4096];
#define _POSIX_SOURCE 1 /* POSIX compliant source */
/*********************************************************************
* DESCRIPTION: Configures the interface name
* RETURN: none
* ALGORITHM: none
* NOTES: none
*********************************************************************/
void RS485_Set_Interface(
char *ifname)
{
/* note: expects a constant char, or char from the heap */
if (ifname) {
RS485_Port_Name = ifname;
}
}
/*********************************************************************
* DESCRIPTION: Returns the interface name
* RETURN: none
* ALGORITHM: none
* NOTES: none
*********************************************************************/
const char *RS485_Interface(
void)
{
return RS485_Port_Name;
}
/****************************************************************************
* DESCRIPTION: Returns the baud rate that we are currently running at * RETURN: none
* ALGORITHM: none