Linux串口UART测试程序，收到什么，打印什么。

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/signal.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>#define FALSE -1
#define TRUE 0
#define flag 1
#define noflag 0int wait_flag = noflag;
int STOP = 0;
int res;int speed_arr[] ={ B38400, B19200, B9600, B4800, B2400, B1200, B300, B38400, B19200, B9600,
B4800, B2400, B1200, B300,B115200 };
int name_arr[] ={ 38400, 19200, 9600, 4800, 2400, 1200, 300, 38400, 19200, 9600, 4800, 2400,
1200, 300, 115200,};
void
set_speed (int fd, int speed)
{int i;int status;struct termios Opt;tcgetattr (fd, &Opt);for (i = 0; i < sizeof (speed_arr) / sizeof (int); i++){if (speed == name_arr[i])if (speed == name_arr[i]){tcflush (fd, TCIOFLUSH);cfsetispeed (&Opt, speed_arr[i]);cfsetospeed (&Opt, speed_arr[i]);status = tcsetattr (fd, TCSANOW, &Opt);if (status != 0){perror ("tcsetattr fd1");return;}tcflush (fd, TCIOFLUSH);}}
}int
set_Parity (int fd, int databits, int stopbits, int parity)
{struct termios options;if (tcgetattr (fd, &options) != 0){perror ("SetupSerial 1");return (FALSE);}options.c_cflag &= ~CSIZE;options.c_lflag &= ~ECHO;  //这个是重点！！！！！！！！ 关闭回显功能 switch (databits){case 7:options.c_cflag |= CS7;break;case 8:options.c_cflag |= CS8;break;default:fprintf (stderr, "Unsupported data size\n");return (FALSE);}switch (parity){case 'n':case 'N':options.c_cflag &= ~PARENB;	/* Clear parity enable */options.c_iflag &= ~INPCK;	/* Enable parity checking */break;case 'o':case 'O':options.c_cflag |= (PARODD | PARENB);options.c_iflag |= INPCK;	/* Disnable parity checking */break;case 'e':case 'E':options.c_cflag |= PARENB;	/* Enable parity */options.c_cflag &= ~PARODD;options.c_iflag |= INPCK;	/* Disnable parity checking */break;case 'S':case 's':			/*as no parity */options.c_cflag &= ~PARENB;options.c_cflag &= ~CSTOPB;break;default:fprintf (stderr, "Unsupported parity\n");return (FALSE);}switch (stopbits){case 1:options.c_cflag &= ~CSTOPB;break;case 2:options.c_cflag |= CSTOPB;break;default:fprintf (stderr, "Unsupported stop bits\n");return (FALSE);}/* Set input parity option */if (parity != 'n')options.c_iflag |= INPCK;tcflush (fd, TCIFLUSH);options.c_cc[VTIME] = 150;options.c_cc[VMIN] = 0;	/* Update the options and do it NOW */if (tcsetattr (fd, TCSANOW, &options) != 0){perror ("SetupSerial 3");return (FALSE);}return (TRUE);
}void
signal_handler_IO (int status)
{printf ("received SIGIO signale.\n");wait_flag = noflag;
}void StrToHex(unsigned char *pbDest, unsigned char *pbSrc, int nLen)
{
char h1,h2;
unsigned char s1,s2;
int i;for (i=0; i<nLen; i++)
{
h1 = pbSrc[2*i];
h2 = pbSrc[2*i+1];s1 = toupper(h1) - 0x30;
if (s1 > 9)
s1 -= 7;s2 = toupper(h2) - 0x30;
if (s2 > 9)
s2 -= 7;pbDest[i] = s1*16 + s2;
}
}void print_use()
{printf("*************Send hex data to uart and waitting timeout recv data************************ \n");printf("uart-test -d [/dev/ttyS0] -b [Baudrate 115200] -s [hex data eg:AA550102] \n");	printf("uart-test -d [/dev/ttyS0] -b [Baudrate 115200] -s [hex data eg:AA550102] \n");printf("uart-test -d [/dev/ttyS0] -b [Baudrate 115200] -s [hex data eg:AA550102] \n");	printf("******************************************************************* \n");}int main (int argc, char* argv[])
{int i=0; int j=0;printf ("This program updates last time at %s   %s\n", __TIME__, __DATE__);printf ("TEST FOR ZTJY IOT HW \n");print_use();if(argc != 7){print_use();return -1;}int fd;// fd = open (argv[2], O_RDWR|);fd = open (argv[2], O_RDWR|O_NOCTTY|O_NONBLOCK); //注意这里的标志位 是重点if (fd == -1){perror ("serialport open error\n");return -1;}else{printf ("open ");printf ("%s", argv[2]);printf (" succesfully\n");}set_speed (fd, atoi(argv[4]));if (set_Parity (fd, 8, 1, 'N') == FALSE){printf ("Set Parity Error\n");exit (0);}unsigned char sendData[1024]={0};StrToHex(sendData,argv[6],strlen(argv[6])/2); write(fd,sendData,strlen(sendData));//fflush();printf("Send Data: \n");for(i=0;i<strlen(sendData);i++)
{printf("-0x%2x-",sendData[i]);
}
printf("\n");char buf[2048];fd_set rd;int nread = 0;while(1){FD_ZERO(&rd);FD_SET(fd, &rd);while(FD_ISSET(fd, &rd)){if(select(fd+1, &rd, NULL,NULL,NULL) < 0){perror("select error\n");}else{while((nread = read(fd, buf, sizeof(buf))) > 0){printf("nread = %d,%s\n",nread, buf);for(j=0;j<nread;j++){printf("-0x%2x-",buf[j]);}printf("\n");printf("\n");printf("\n");memset(buf, 0 , sizeof(buf));printf("Exit uart-teset App\r\n");break;}}}}close (fd);printf("Exit uart-teset App");return 0;
}