linux 串口编程实现代码
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在看本程序时先阅读http://blog.csdn.net/u013711616/article/details/52190901，方便对linux串口编程有更好的理解。已下两个代码都是测试通过的。
代码一，所有的设备信息可选
/************************************************************************* > File Name: uart.c > Author: >程序测试完好，能实现一次性读取所有串口内容，特测保存。请勿修改 ************************************************************************/#include<stdio.h>#include<stdlib.h>#include<string.h>#include<sys/types.h>#include<sys/stat.h>#include<fcntl.h>#include<unistd.h>#include<termios.h>#include<string.h>#include <errno.h>int set_opt(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; //CLOCAL:忽略modem控制线 CREAD：打开接受者 newtio.c_cflag &= ~CSIZE; //字符长度掩码。取值为：CS5，CS6，CS7或CS8 switch (nBits) { case 7: newtio.c_cflag |= CS7; break; case 8: newtio.c_cflag |= CS8; break; } switch (nEvent) { case 'O': newtio.c_cflag |= PARENB; //允许输出产生奇偶信息以及输入到奇偶校验 newtio.c_cflag |= PARODD; //输入和输出是奇及校验 newtio.c_iflag |= (INPCK | ISTRIP); // INPACK:启用输入奇偶检测；ISTRIP：去掉第八位 break; case 'E': newtio.c_iflag |= (INPCK | ISTRIP); newtio.c_cflag |= PARENB; newtio.c_cflag &= ~PARODD; break; case 'N': 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; //CSTOPB:设置两个停止位，而不是一个 } else if (nStop == 2) { newtio.c_cflag |= CSTOPB; } newtio.c_cc[VTIME] = 0; //VTIME:非cannoical模式读时的延时，以十分之一秒位单位 newtio.c_cc[VMIN] = 0; //VMIN:非canonical模式读到最小字符数 //tcflush(fd,TCIFLUSH); // 改变在所有写入 fd 引用的对象的输出都被传输后生效，所有已接受但未读入的输入都在改变发生前丢弃。 tcflush(fd, TCIOFLUSH); if((tcsetattr(fd,TCSANOW,&newtio))!=0) //TCSANOW:改变立即发生 { perror("com set error"); return -1; } printf("set done!\n\r"); return 0;}ssize_t tread(int fd, void *buf, size_t nbytes, unsigned int timout){ int nfds; fd_set readfds; struct timeval tv; tv.tv_sec = timout; tv.tv_usec = 0; FD_ZERO(&readfds); FD_SET(fd, &readfds); nfds = select(fd+1, &readfds, NULL, NULL, &tv); if (nfds <= 0) { if (nfds == 0) errno = ETIME; return(-1); } return(read(fd, buf, nbytes));}ssize_t treadn(int fd, void *buf, size_t nbytes, unsigned int timout){ size_t nleft; ssize_t nread; nleft = nbytes; while (nleft > 0) { if ((nread = tread(fd, buf, nleft, timout)) < 0) { if (nleft == nbytes) return(-1); /* error, return -1 */ else break; /* error, return amount read so far */ } else if (nread == 0) { break; /* EOF */ } nleft -= nread; buf += nread; } return(nbytes - nleft); /* return >= 0 */}int main(void){ int fd1,nset,ret; char buf[100]={"test com data!...........\n"}; char buf1[100]; fd1 = open( "/dev/ttyATH0", O_RDWR|O_NOCTTY|O_NDELAY); if (fd1 == -1) exit(1); printf("open ttyATH0 success!!\n"); nset = set_opt(fd1, 9600, 8, 'N', 1); if (nset == -1) exit(1); printf("SET ttyATH0 success!!\n"); int idx = 0; while (1) { printf("0!\n"); memset(buf1, 0, sizeof(buf1)); idx = strlen(buf); ret = write(fd1, buf, idx); if (ret >= idx) { printf("write success len = %d! wait data receive\n", ret); } printf("1!!\n"); int retv = -1; //read with timeout unsigned int timeout = 2; retv = treadn(fd1, buf1, ret, timeout); if (retv > 0) { printf("nread: %d\n", retv); buf1[retv] = '\0'; printf("redatad: nread = %s\n", buf1); } printf("2!!!\n"); sleep(2); } close(fd1); return 0;}代码二，串口参数不可选择
/************************************************************************* > File Name: uart.c > Author: ************************************************************************/#include <stdio.h> #include <stdlib.h> #include <unistd.h>#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <termios.h> #include <errno.h> #include <pthread.h>#include <string.h>#include <semaphore.h>#define UART_DEVNAME "/dev/ttyATH0"// Uart file descriptorstatic int uartFD = -1;// 初始化静态锁static pthread_mutex_t uartMutex = PTHREAD_MUTEX_INITIALIZER;ssize_t tread(int fd, void *buf, size_t nbytes, unsigned int timout);ssize_t treadn(int fd, void *buf, size_t nbytes, unsigned int timout);int writemsg(int fd);void* create_uart_server_thread(void *ptr);int main(int argc, char *argv[]){ int retv = -1; pthread_t pid; retv = pthread_create(&pid, NULL, create_uart_server_thread, NULL); if (retv < 0) { printf("create thread failed!!\n"); } //main loop while(1) { usleep(1000); } return 0;}ssize_t tread(int fd, void *buf, size_t nbytes, unsigned int timout){ int nfds; fd_set readfds; struct timeval tv; tv.tv_sec = timout; tv.tv_usec = 0; FD_ZERO(&readfds); FD_SET(fd, &readfds); nfds = select(fd+1, &readfds, NULL, NULL, &tv); if (nfds <= 0) { if (nfds == 0) errno = ETIME; return(-1); } return(read(fd, buf, nbytes));}ssize_t treadn(int fd, void *buf, size_t nbytes, unsigned int timout){ size_t nleft; ssize_t nread; nleft = nbytes; while (nleft > 0) { if ((nread = tread(fd, buf, nleft, timout)) < 0) { if (nleft == nbytes) return(-1); /* error, return -1 */ else break; /* error, return amount read so far */ } else if (nread == 0) { break; /* EOF */ } nleft -= nread; buf += nread; } return(nbytes - nleft); /* return >= 0 */}int writemsg(int fd){ unsigned char packet[128] = {0, }; unsigned char padded[7]= {0,}; unsigned char MAC[6] = { 0x01,0x00, 0x00, 0xAC, 0xA3, 0xDC}; memcpy(packet+20, MAC, 6); packet[26] = 'Z'; packet[27] = 'H'; packet[28] = 'A'; packet[29] = 'O'; packet[30] = 0x01; packet[31] = 0x02; packet[32] = 0x13; packet[33] = 0x04; packet[34] = 0x05; memcpy(packet+35, padded, 7); return write(fd, packet, 42);}/* *create_uart_server_thread(); */void* create_uart_server_thread(void *ptr){ //New serial port configuration information struct termios options;retry_uart: uartFD = -1; //open uart uartFD = open(UART_DEVNAME, O_RDWR | O_NOCTTY | O_NDELAY); if(uartFD == -1) { printf("%s Can not open uart %s!\n", __func__, UART_DEVNAME); usleep(1000); goto retry_uart; } //Save the original serial port configuration if (tcgetattr(uartFD, &options) != 0) { printf("%s tcgetattr failed !\n", __func__); close(uartFD); goto retry_uart; } memset(&options, 0x0, sizeof(options)); //Enable the receiver and set local mode... options.c_cflag |= (CLOCAL | CREAD); // Set the baud rate cfsetispeed(&options, B115200); cfsetospeed(&options, B115200); //Setting stop bits one bit stop options.c_cflag &= ~CSTOPB; //set data bits 8 data bits Mask the character size bits options.c_cflag |= CS8; options.c_cflag &= ~CSIZE; //set The parits No parity options.c_cflag &= ~PARENB; options.c_iflag &= ~INPCK; //Setting data flow control No flow control options.c_cflag &= ~CRTSCTS; //Modify the output mode, raw data output //使用原始模式(Raw Mode)方式来通讯,修改输出模式，原始数据输出 options.c_oflag &= ~OPOST; options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); //To disable software flow control simply mask those bits //防止XON和XOFF字符无法发送 options.c_iflag &= ~(IXON | IXOFF | IXANY); //Serial port can prevent carriage return and line as the same character //防止串口能把回车和换行当成同一个字符(防止发送字符0x0d，在接收端变成0x0a) options.c_iflag &= ~(INLCR | ICRNL | IGNCR); options.c_oflag &= ~(ONLCR | OCRNL); //Setting the minimum wait time and receive characters options.c_cc[VTIME] = 0; options.c_cc[VMIN] = 0; // Flush Input Stream buffer tcflush(uartFD, TCIOFLUSH); //Enable configure if (tcsetattr(uartFD, TCSANOW, &options) != 0) { printf("%s: Uart set failed!\n", __func__); close(uartFD); goto retry_uart; } printf("%s: UART open Ok!\n", __func__); unsigned char ubuff[128] = {0, }; unsigned int ulen = 0; //uart process while(1) { unsigned char rxbuf[128] = {0, }; int readn = 0; int writen = -1; int idx = 0; //lock pthread_mutex_lock(&uartMutex); //write writen = writemsg(uartFD); if( writen < 42) { printf("%s: write failed! writen = %02d\n", __func__, writen); close(uartFD); pthread_mutex_unlock(&uartMutex); goto retry_uart; } printf("write success len = %d! wait data receive\n", writen); //read unsigned int timeout = 2; readn = treadn(uartFD, rxbuf, writen, timeout); if (readn < 0) { printf("%s: read failed! readn = %02d\n", __func__, readn); close(uartFD); pthread_mutex_unlock(&uartMutex); goto retry_uart; } //unlock pthread_mutex_unlock(&uartMutex); for (idx = 0; idx <readn; idx++) { printf("%02X ",rxbuf[idx]); } printf("\n"); } close(uartFD); return 0;} 0 0
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