app/src/serial.c

#define LOG_TAG "serial"
#include "serial.h"
#include "elog.h"
#include <sys/time.h>
/*
TTU使用4路UART实现两路RS485串口、两路RS232/RS485可切换串口，设备节点与串口对应关系为:
UART 设备节点  		 对应串口 	 GPIO状态
3    /dev/ttySZ3   	RS485-1		-	  	
4	 /dev/ttySZ4	RS485-2		-
5	 /dev/ttySZ5	RS485-3	  PB08为高电平
6	 /dev/ttySZ6	RS485-4	  PB09为高电平
7	 /dev/ttySZ5    RS232-1	  PB08为低电平
8	 /dev/ttySZ6	RS232-2	  PB09为低电平
详情参考:边缘计算框架使用说明/融合终端驱动程序使用说明书
*/

static int speed_arr[] = {B115200,B57600,B38400,B19200,B9600,B4800,B2400,B1200,B300};
static int name_arr[] =  {115200,57600,38400,19200,9600,4800,2400,1200,300};

// Common Helper /////////////////////////////////////////////////////////////
//
static void SetACommMode(int fd,int combaud,int databit,int stopbit,int checkmode)
{
	struct termios tty_termios;
	int	flags;
	unsigned int i;

	if ((tcgetattr(fd, &tty_termios) == -1)) {
		log_e("tcgetattr()");
		return;
	}
	cfmakeraw(&tty_termios);
	for (i=0; i<sizeof(speed_arr)/sizeof(int); i++) {
		if (combaud == name_arr[i]) {
			cfsetispeed(&tty_termios, speed_arr[i]);
			cfsetospeed(&tty_termios, speed_arr[i]);
			break;
		}
	}

	tty_termios.c_cflag &= ~CSIZE;
	switch (databit) {
	case 7:
		tty_termios.c_cflag |= CS7;
		break;
	case 8:
	default:
		tty_termios.c_cflag |= CS8;
		break;
	}

	switch (checkmode) {
	case 0://none
		tty_termios.c_cflag &= ~PARENB;
		tty_termios.c_iflag &= ~INPCK;
		break;
	case 1://ji
		tty_termios.c_cflag |= (PARODD | PARENB);
		tty_termios.c_iflag |= INPCK;
		break;
	case 2://ou
		tty_termios.c_cflag |= PARENB;	// Enable parity????У?? 
		tty_termios.c_cflag &= ~PARODD; //?????У?? 
		tty_termios.c_iflag |= INPCK;   //???У????? 
		break;
	default:
		tty_termios.c_cflag &= ~PARENB;
		tty_termios.c_iflag &= ~INPCK;
		break;
	}

	// Set input parity option
	if (checkmode)
		tty_termios.c_iflag |= INPCK;

	// Set stop bit
	switch (stopbit) {
	case 1:
		tty_termios.c_cflag &= ~CSTOPB;
		break;
	case 2:
		tty_termios.c_cflag |= CSTOPB;
		break;
	default:
		tty_termios.c_cflag &= ~CSTOPB;
		break;
	}

	tty_termios.c_cflag|=(CLOCAL|CREAD);//new add
	
	tty_termios.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  // Input
	
	tty_termios.c_oflag  &= ~OPOST;	// Output
	tty_termios.c_oflag &=~(ONLCR|OCRNL);//new add
	
	tty_termios.c_iflag &=~(ICRNL|INLCR);//new add
	tty_termios.c_iflag &=~(IXON|IXOFF|IXANY);//new add
	
	tty_termios.c_cc[VTIME] = 0;	// Set timeout 0 seconds
	tty_termios.c_cc[VMIN] = 0; 	// Update the tty_termios and do it NOW

	if(tcsetattr(fd,TCSANOW,&tty_termios)!=0) {
		log_e("tcsetattr()");
	}
	tcflush(fd,TCIOFLUSH);
	
	flags = fcntl(fd,F_GETFL);
	//fcntl(fd,F_SETFL,flags|FNDLAY);
	fcntl(fd,F_SETFL,flags|O_NONBLOCK);
}


int SerialOpen(const char *dev_name,int baud,int databit,int stopbit,int chk_mode)
{
  int com_fd;
  if((com_fd=open(dev_name,O_RDWR|O_NOCTTY|O_NONBLOCK))==-1) 
    {
      log_e("SerialOpen failed");
      return -1;
    }		
  SetACommMode(com_fd,baud,databit,stopbit,chk_mode);//
  return com_fd;
}


/**
 * Read from Serial device
 * @param	timeout		millisecond
 */
int SerialRead(int m_comFd,unsigned char *buf,int sz,int timeout)
{
   int iDataNum;
   int rxlen = 0;
   int recvflag = 0;

   if(timeout<0)
     return 0;

   if(timeout>0)
     timeout /= 100;

   
#ifdef DEBUG_COM
	int i;
	printf("RX:\t");
#endif

    for(;;) 
      {
		iDataNum = read(m_comFd,buf+rxlen,sz-rxlen);
#ifdef DEBUG_COM
		for (int i = 0; i < iDataNum; i++) {
			printf("%02X ", buf[rxlen + i]);
			if (!((i + 1) % 10))
				printf("\n\t");
		}
#endif

		if (iDataNum <= 0) {
			if (recvflag==0 && timeout--)
				usleep(100000);//100ms
			else
				break;
		} else {
			recvflag = 1;
			rxlen += iDataNum;
		}
	}

	return (rxlen > 0) ? rxlen : 0;
}

long long get_msec(void)
{
	struct timeval tv;
	long long time_in_msec = 0;

	gettimeofday(&tv, NULL);
	time_in_msec = tv.tv_sec;
	time_in_msec *= 1000;
	time_in_msec += tv.tv_usec / 1000;

	return time_in_msec;
}

#if 0
//timeout is in 100ms
int SerialReadEx(int m_comFd,unsigned char *buf,int sz,int timeout)
{
	int curr_length=0,last_length=0,rx_length=0;
	//int rx_tick=0;
	//tcflush(m_comFd,TCIFLUSH);
	while(timeout--)
	{
		usleep(100000);//wait 100ms
		curr_length=read(m_comFd,buf+rx_length,sz-rx_length);
		if(curr_length>0)
		{
			rx_length+=curr_length;
			last_length=curr_length;
			if(rx_length>=sz)
			{
				return rx_length;
			}
		}
		else
		{
			if(last_length>0)//上次读取到了字节本次没有,认为读完了一帧
			{
				return rx_length; 
			}
			last_length=0;
			//rx_length=0;
		}
	}
	return rx_length; 	
}
#endif

int SerialReadEx(int m_comFd,unsigned char *buf,int sz,int timeout)
{
	int curr_length=0/*,last_length=0*/,rx_length=0;

    long long  t0, t1;

   t0 = get_msec();

	for(;;)
    {
        rx_length += curr_length;
		usleep(5000);
        curr_length = read(m_comFd,buf+rx_length, 1040-rx_length);/* 在串口读取字符串 */
        t1 = get_msec();
        if(t1-t0 >= 350)
            break;
    }
	if (rx_length < 1)
		return rx_length;
	
	return rx_length; 	
}

/**
 * Write to Serial device
 */
int SerialWrite(int m_comFd,const unsigned char *buf,int sz)
{
	// Avoid rush
	usleep(10000);
	tcflush(m_comFd,TCOFLUSH);
	if (write(m_comFd, buf, sz) != sz) {
		log_e("SerialWrite:write()");
	  return -1;
	}

#ifdef DEBUG_COM
	int i;
	printf("\nTX:\t");
	for (i = 0; i < len; i++) {
		printf("%02X ", buf[i]);
		if (!((i + 1) % 10))
			printf("\n\t");
	}
	printf("\n");
	fflush(stdout);
#endif
  return sz;
}