Linux下串口通讯，完整程序

程序代码已经在Linux系统上正确运行

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <fcntl.h>#include <unistd.h>#include <termios.h> //set baud rate#include <sys/select.h>#include <sys/time.h>#include <sys/types.h>#include <errno.h>#include <sys/stat.h>//#define rec_buf_wait_2s 2#define buffLen 1024#define rcvTimeOut 2/*******************************************************//**下面的函数暂时并没什么意思，完全可以忽略**/int read_data_tty(int fd, char *rec_buf, int rec_wait) {int retval;fd_set rfds;struct timeval tv;int ret, pos;tv.tv_sec = rec_wait;tv.tv_usec = 0;pos = 0;while (1) {FD_ZERO(&rfds);FD_SET(fd, &rfds);retval = select(fd + 1, &rfds, NULL, NULL, &tv);if (retval == -1) {perror("select()");break;}else if (retval) {ret = read(fd, rec_buf + pos, 2048);pos += ret;if (rec_buf[pos - 2] == '\r' && rec_buf[pos - 1] == '\n') {FD_ZERO(&rfds);FD_SET(fd, &rfds);retval = select(fd + 1, &rfds, NULL, NULL, &tv);if (!retval) {break;}}}else {break;}}return 1;}int device_485_receive(int fd) {int ret;char rec_buf[1024];int i;char send_buf[] = { "02030202f925" };for (i = 0; i<10; i++) {/*ret = write(fd, send_buf, strlen(send_buf));if (ret == -1) {printf("write device %s error\n", device);return -1;}*///if (read_data_tty(fd, rec_buf, rec_buf_wait_2s)) {if (read_data_tty(fd, rec_buf,2)) {printf("%s\n", rec_buf);}else {printf("read_error\n");}//if ((read(fd, rec_buf, strlen(rec_buf))) == -1) {//      printf("error reading string\n");//      return -1;//} else {//      printf("%s\n", rec_buf);}return 0;}/*-----------------------------------------------------*//*******************************************************//*************Linux and Serial Port *********************//*************Linux and Serial Port *********************/int openPort(int fd, int comport){if (comport == 1){fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);if (-1 == fd){perror("Can't Open Serial Port");return(-1);}else{printf("open ttyS0 .....\n");}}else if (comport == 2){fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);if (-1 == fd){perror("Can't Open Serial Port");return(-1);}else{printf("open ttyS1 .....\n");}}else if (comport == 3){fd = open("/dev/ttyS2", O_RDWR | O_NOCTTY | O_NDELAY);if (-1 == fd){perror("Can't Open Serial Port");return(-1);}else{printf("open ttyS2 .....\n");}}/*************************************************/else if (comport == 4){fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);if (-1 == fd){perror("Can't Open Serial Port");return(-1);}else{printf("open ttyUSB0 .....\n");}}if (fcntl(fd, F_SETFL, 0)<0){printf("fcntl failed!\n");}else{printf("fcntl=%d\n", fcntl(fd, F_SETFL, 0));}if (isatty(STDIN_FILENO) == 0){printf("standard input is not a terminal device\n");}else{printf("is a tty success!\n");}printf("fd-open=%d\n", fd);return fd;}int setOpt(int fd, int nSpeed, int nBits, char nEvent, int nStop){struct termios newtio, oldtio;if (tcgetattr(fd, &oldtio) != 0){perror("SetupSerial 1");return -1;}bzero(&newtio, sizeof(newtio));newtio.c_cflag |= CLOCAL | CREAD;newtio.c_cflag &= ~CSIZE;switch (nBits){case 7:newtio.c_cflag |= CS7;break;case 8:newtio.c_cflag |= CS8;break;}switch (nEvent){case 'O':                     //奇校验newtio.c_cflag |= PARENB;newtio.c_cflag |= PARODD;newtio.c_iflag |= (INPCK | ISTRIP);break;case 'E':                     //偶校验newtio.c_iflag |= (INPCK | ISTRIP);newtio.c_cflag |= PARENB;newtio.c_cflag &= ~PARODD;break;case 'N':                    //无校验newtio.c_cflag &= ~PARENB;break;}switch (nSpeed){case 2400:cfsetispeed(&newtio, B2400);cfsetospeed(&newtio, B2400);break;case 4800:cfsetispeed(&newtio, B4800);cfsetospeed(&newtio, B4800);break;case 9600:cfsetispeed(&newtio, B9600);cfsetospeed(&newtio, B9600);break;case 115200:cfsetispeed(&newtio, B115200);cfsetospeed(&newtio, B115200);break;default:cfsetispeed(&newtio, B9600);cfsetospeed(&newtio, B9600);break;}if (nStop == 1){newtio.c_cflag &= ~CSTOPB;}else if (nStop == 2){newtio.c_cflag |= CSTOPB;}newtio.c_cc[VTIME] = 0;newtio.c_cc[VMIN] = 0;tcflush(fd, TCIFLUSH);if ((tcsetattr(fd, TCSANOW, &newtio)) != 0){perror("com set error");return -1;}printf("set done!\n");return 0;}int readDataTty(int fd, char *rcv_buf, int TimeOut, int Len){int retval;fd_set rfds;struct timeval tv;int ret, pos;tv.tv_sec = TimeOut / 1000;  //set the rcv wait time  tv.tv_usec = TimeOut % 1000 * 1000;  //100000us = 0.1s  pos = 0;while (1){FD_ZERO(&rfds);FD_SET(fd, &rfds);retval = select(fd + 1, &rfds, NULL, NULL, &tv);if (retval == -1){perror("select()");break;}else if (retval){ret = read(fd, rcv_buf + pos, 1);if (-1 == ret){break;}pos++;if (Len <= pos){break;}}else{break;}}return pos;}int sendDataTty(int fd, char *send_buf, int Len){ssize_t ret;ret = write(fd, send_buf, Len);if (ret == -1){printf("write device error\n");return -1;}return 1;}//这个函数已经没有用了，修改设备不在这里改，在主函数的fdSerial = openPort(fdSerial, 2)函数处，修改void serialInit(void)//这个函数已经没有用了，修改设备不在这里改，在主函数的fdSerial = openPort(fdSerial, 2)函数处，修改{int fd = 0;fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);//串口2if (1){setOpt(fd, 9600, 8, 'N', 1);//set_opt(SerFd, BAUD_115200, DATA_BIT_8, PARITY_NONE, STOP_BIT_1);}else{printf("open_port ERROR !\n");}}int main(int argc, char** argv){int iSetOpt = 0;//SetOpt 的增量i//serialInit();//send_data_tty(SerFd, "hello series\n", sizeof("hello series\n"));int fdSerial = 0;//openPortif ((fdSerial = openPort(fdSerial, 4))<0)//1--"/dev/ttyS0",2--"/dev/ttyS1",3--"/dev/ttyS2",4--"/dev/ttyUSB0" 小电脑上是2--"/dev/ttyS1"{perror("open_port error");return -1;}//setOpt(fdSerial, 9600, 8, 'N', 1)if ((iSetOpt = setOpt(fdSerial, 9600, 8, 'N', 1))<0){perror("set_opt error");return -1;}printf("Serial fdSerial=%d\n", fdSerial);tcflush(fdSerial, TCIOFLUSH);//清掉串口缓存fcntl(fdSerial, F_SETFL, 0);char buffRcvData[buffLen] = { 0 };unsigned int readDataNum = 0;buffRcvData[0] = 's';buffRcvData[1] = 't';buffRcvData[2] = 'a';buffRcvData[3] = 'r';buffRcvData[4] = 't';sendDataTty(fdSerial, buffRcvData, 5);while (1){readDataNum = readDataTty(fdSerial, buffRcvData, rcvTimeOut, buffLen);sendDataTty(fdSerial, buffRcvData, readDataNum);}return 1;}