linux 串口通讯 实例

//////////////////////////////////////////////////////////////////////////////// //stty.c //////////////////////////////////////////////////////////////////////////////// #include <stdio.h> #include <sys/ioctl.h> #include "stty.h" /////////////////////////////////////////////////////////////////////////////// // 初始化串口设备并进行原有设置的保存 TTY_INFO *readyTTY(int id) { TTY_INFO *ptty; ptty = (TTY_INFO *)malloc(sizeof(TTY_INFO)); if(ptty == NULL) return NULL; memset(ptty,0,sizeof(TTY_INFO)); pthread_mutex_init(&ptty->mt,NULL); sprintf(ptty->name,"/dev/ttyS%d",id); // // 打开并且设置串口 ptty->fd = open(ptty->name, O_RDWR | O_NOCTTY |O_NDELAY); if (ptty->fd <0) { free(ptty); return NULL; } // // 取得并且保存原来的设置 tcgetattr(ptty->fd,&ptty->otm); return ptty; } /////////////////////////////////////////////////////////////////////////////// // 清理串口设备资源 int cleanTTY(TTY_INFO *ptty) { // // 关闭打开的串口设备 if(ptty->fd>0) { tcsetattr(ptty->fd,TCSANOW,&ptty->otm); close(ptty->fd); ptty->fd = -1; free(ptty); ptty = NULL; } return 0; } /////////////////////////////////////////////////////////////////////////////// // 设置串口通信速率 // ptty 参数类型(TTY_INFO *),已经初始化的串口设备信息结构指针 // speed 参数类型(int),用来设置串口的波特率 // return 返回值类型(int),函数执行成功返回零值，否则返回大于零的值 /////////////////////////////////////////////////////////////////////////////// int setTTYSpeed(TTY_INFO *ptty, int speed) { int i; // // 进行新的串口设置,数据位为8位 bzero(&ptty->ntm, sizeof(ptty->ntm)); tcgetattr(ptty->fd,&ptty->ntm); ptty->ntm.c_cflag = /*CS8 |*/ CLOCAL | CREAD; switch(speed) { case 300: ptty->ntm.c_cflag |= B300; break; case 1200: ptty->ntm.c_cflag |= B1200; break; case 2400: ptty->ntm.c_cflag |= B2400; break; case 4800: ptty->ntm.c_cflag |= B4800; break; case 9600: ptty->ntm.c_cflag |= B9600; break; case 19200: ptty->ntm.c_cflag |= B19200; break; case 38400: ptty->ntm.c_cflag |= B38400; break; case 115200: ptty->ntm.c_cflag |= B115200; break; } ptty->ntm.c_iflag = IGNPAR; ptty->ntm.c_oflag = 0; // // tcflush(ptty->fd, TCIFLUSH); tcsetattr(ptty->fd,TCSANOW,&ptty->ntm); // // return 0; } /////////////////////////////////////////////////////////////////////////////// // 设置串口数据位，停止位和效验位 // ptty 参数类型(TTY_INFO *),已经初始化的串口设备信息结构指针 // databits 参数类型(int), 数据位,取值为7或者8 // stopbits 参数类型(int),停止位,取值为1或者2 // parity 参数类型(int),效验类型 取值为N,E,O,S // return 返回值类型(int),函数执行成功返回零值，否则返回大于零的值 /////////////////////////////////////////////////////////////////////////////// int setTTYParity(TTY_INFO *ptty,int databits,int parity,int stopbits) { // // 取得串口设置 if( tcgetattr(ptty->fd,&ptty->ntm) != 0 ) { printf("SetupSerial [%s]n",ptty->name); return 1; } bzero(&ptty->ntm, sizeof(ptty->ntm)); ptty->ntm.c_cflag = CS8 | CLOCAL | CREAD; ptty->ntm.c_iflag = IGNPAR; ptty->ntm.c_oflag = 0; // // 设置串口的各种参数 ptty->ntm.c_cflag &= ~CSIZE; switch (databits) { //设置数据位数 case 7: ptty->ntm.c_cflag |= CS7; break; case 8: ptty->ntm.c_cflag |= CS8; break; default: printf("Unsupported data sizen"); return 5; } // // switch (parity) { // 设置奇偶校验位数 case 'n': case 'N': ptty->ntm.c_cflag &= ~PARENB; /* Clear parity enable */ ptty->ntm.c_iflag &= ~INPCK; /* Enable parity checking */ break; case 'o': case 'O': ptty->ntm.c_cflag |= (PARODD|PARENB); /* 设置为奇效验*/ ptty->ntm.c_iflag |= INPCK; /* Disnable parity checking */ break; case 'e': case 'E': ptty->ntm.c_cflag |= PARENB; /* Enable parity */ ptty->ntm.c_cflag &= ~PARODD; /* 转换为偶效验*/ ptty->ntm.c_iflag |= INPCK; /* Disnable parity checking */ break; case 'S': case 's': /*as no parity*/ ptty->ntm.c_cflag &= ~PARENB; ptty->ntm.c_cflag &= ~CSTOPB; break; default: printf("Unsupported parityn"); return 2; } // // 设置停止位 switch (stopbits) { case 1: ptty->ntm.c_cflag &= ~CSTOPB; break; case 2: ptty->ntm.c_cflag |= CSTOPB; break; default: printf("Unsupported stop bitsn"); return 3; } // // ptty->ntm.c_lflag = 0; ptty->ntm.c_cc[VTIME] = 0; // inter-character timer unused ptty->ntm.c_cc[VMIN] = 1; // blocking read until 1 chars received tcflush(ptty->fd, TCIFLUSH); if (tcsetattr(ptty->fd,TCSANOW,&ptty->ntm) != 0) { printf("SetupSerial n"); return 4; } return 0; } int recvnTTY(TTY_INFO *ptty,char *pbuf,int size) { int ret,left,bytes; left = size; while(left>0) { ret = 0; bytes = 0; pthread_mutex_lock(&ptty->mt); ioctl(ptty->fd, FIONREAD, &bytes); if(bytes>0) { ret = read(ptty->fd,pbuf,left); } pthread_mutex_unlock(&ptty->mt); if(ret >0) { left -= ret; pbuf += ret; } usleep(100); } return size - left; } int sendnTTY(TTY_INFO *ptty,char *pbuf,int size) { int ret,nleft; char *ptmp; ret = 0; nleft = size; ptmp = pbuf; while(nleft>0) { pthread_mutex_lock(&ptty->mt); ret = write(ptty->fd,ptmp,nleft); pthread_mutex_unlock(&ptty->mt); if(ret >0) { nleft -= ret; ptmp += ret; } //usleep(100); } return size - nleft; } int lockTTY(TTY_INFO *ptty) { if(ptty->fd < 0) { return 1; } return flock(ptty->fd,LOCK_EX); } int unlockTTY(TTY_INFO *ptty) { if(ptty->fd < 0) { return 1; } return flock(ptty->fd,LOCK_UN); } /////////////////////////////////////////////////////////////////////////////// // 接口测试 /////////////////////////////////////////////////////////////////////////////// #ifdef LEAF_TTY_TEST int main(int argc,char **argv) { TTY_INFO *ptty; int nbyte,idx; unsigned char cc[16]; ptty = readyTTY(0); if(ptty == NULL) { printf("readyTTY(0) errorn"); return 1; } // // lockTTY(ptty); if(setTTYSpeed(ptty,9600)>0) { printf("setTTYSpeed() errorn"); return -1; } if(setTTYParity(ptty,8,'N',1)>0) { printf("setTTYParity() errorn"); return -1; } // idx = 0; while(1) { cc[0] = 0xFA; sendnTTY(ptty,&cc[0],1); nbyte = recvnTTY(ptty,cc,1); printf("%d:%02Xn",idx++,cc[0]); } cleanTTY(ptty); } #endif