串口读取示例

「爱情、让人受尽委屈。」 2022-11-22 10:28 138阅读 0赞

波特率必须设置，采用系统默认的会产生问题

#include <stdio.h>
    #include <stdlib.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <assert.h>
    #include <termios.h>
    #include <sys/time.h>
    #include <time.h>
    #include <sys/types.h>
    #include <errno.h>
    #include <sys/select.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #define BAUD 9600
    #define SERVERPORT 8500
    #define MAX_FD_NUM 32
    static int ret = -1;
    static int fdSerial = -1;
    static int fdServer = -1;
    
    
    int uart_set(int fdSerial,int nSpeed, int nBits, char nEvent, int nStop)
    { 
         struct termios newtio,oldtio;
         if  ( tcgetattr( fdSerial,&oldtio)  !=  0) { 
          perror("SetupSerial 1");
          printf("tcgetattr( fdSerial,&oldtio) -> %d\n",tcgetattr( fdSerial,&oldtio));
          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':
         case 'O':
          newtio.c_cflag |= PARENB;
          newtio.c_cflag |= PARODD;
          newtio.c_iflag |= (INPCK | ISTRIP);
          break;
         case 'e':
         case 'E':
          newtio.c_iflag |= (INPCK | ISTRIP);
          newtio.c_cflag |= PARENB;
          newtio.c_cflag &= ~PARODD;
          break;
         case 'n':
         case 'N':
          newtio.c_cflag &= ~PARENB;
          break;
         default:
          break;
         }
    
         /*设置波特率*/
    
    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;
         case 460800:
          cfsetispeed(&newtio, B460800);
          cfsetospeed(&newtio, B460800);
          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(fdSerial,TCIFLUSH);
    
    if((tcsetattr(fdSerial,TCSANOW,&newtio))!=0)
         { 
          perror("com set error");
          return -1;
         }
         printf("set done!\n");
         return 0;
    }
    
    int uart_close(int fdSerial)
    { 
        assert(fdSerial);
        close(fdSerial);
        return 0;
    }
    
    int uart_open(int fdSerial,const char *pathname)
    { 
        fdSerial = open(pathname, O_RDWR|O_NOCTTY);
        uart_set(fdSerial,BAUD,8,0,0);
        if (-1 == fdSerial)
        { 
            perror("Can't Open Serial Port");
            return(-1);
        }
        else
            printf("open %s success!\n",pathname);
        if(isatty(STDIN_FILENO)==0)
            printf("standard input is not a terminal device\n");
        else
            printf("isatty success!\n");
        return fdSerial;
    }
    
    int send_data(int  fdSerial, char *send_buffer,int length)
    { 
        length=write(fdSerial,send_buffer,length*sizeof(unsigned char));
        return length;
    }
    
    int recv_data(int fdSerial, char* recv_buffer,int length)
    { 
        length=read(fdSerial,recv_buffer,length);
        return length;
    }
    
    float a[3],w[3],Angle[3],h[3],Q[4];
    void ParseData(char chr)
    { 
        static char chrBuf[100];
        static unsigned char chrCnt=0;
        signed short sData[4];
        unsigned char i;
    
        time_t now;
        chrBuf[chrCnt++]=chr;
        //直到接收一整包 11个字节
        if (chrCnt<11) return;
        //如果一包的数据是串的，数据前移动，直到接受到一个完整的包为止
        if ((chrBuf[0]!=0x55)||((chrBuf[1]&0x50)!=0x50)) { /*printf("Error:%x %x\r\n",chrBuf[0],chrBuf[1]);*/memcpy(&chrBuf[0],&chrBuf[1],10);chrCnt--;return;}
        //16进制--->10进制
        memcpy(&sData[0],&chrBuf[2],8);
        switch(chrBuf[1])
        { 
                case 0x51:
                    for (i=0;i<3;i++) a[i] = (float)sData[i]/32768.0*16.0;
                    time(&now);
                    printf("\r\nT:%s a:%6.3f %6.3f %6.3f ",asctime(localtime(&now)),a[0],a[1],a[2]);
                    break;
                case 0x52:
                    for (i=0;i<3;i++) w[i] = (float)sData[i]/32768.0*2000.0;
                    printf("w:%7.3f %7.3f %7.3f ",w[0],w[1],w[2]);
                    break;
                case 0x53:
                    for (i=0;i<3;i++) Angle[i] = (float)sData[i]/32768.0*180.0;
                    printf("A:%4.3f,B:%4.3f,C:%4.3f \n",Angle[0],Angle[1],Angle[2]);
                    break;
                case 0x54:
                    for (i=0;i<3;i++) h[i] = (float)sData[i];
                    printf("h:%4.0f %4.0f %4.0f ",h[0],h[1],h[2]);
                    break;
                case 0x59:
                    for (i=0;i<4;i++) Q[i] = (float)sData[i]/32768.0;
                    printf("q0:%4.5f,q1:%4.5f,q2:%4.5f,q3:%4.5f\n",Q[0],Q[1],Q[2],Q[3]);
                    break;
        }
        chrCnt=0;
    }
    
    int client_request(int s)
    { 
        static char ibuf[1024];
        int nbytes = recv(s, ibuf, sizeof(ibuf), 0);
        if (nbytes > 0) { 
            ibuf[nbytes] = '\0';
            if (strcmp(ibuf, "get_dist") == 0) { 
                sprintf(ibuf, "%f,%f,%f,%f\r", Q[0],-Q[1],-Q[2],-Q[3]);
                write(s, ibuf, strlen(ibuf));
            }
        }
        return nbytes;
    }
    
    int open_serial()
    { 
        fdSerial = uart_open(fdSerial,"/dev/ttyUSB0");/*串口号/dev/ttySn,USB口号/dev/ttyUSBn */
        if(fdSerial == -1)
        { 
            fprintf(stderr,"uart_open error\n");
            exit(EXIT_FAILURE);
        }
        return fdSerial;
    }
    
    int main(void)
    { 
        int maxfd = 0;
        int loopIndex = 0;
        fd_set all_fds;
        fd_set select_fds;
        FD_ZERO(&all_fds);
        FD_ZERO(&select_fds);
        char r_buf[1024];
        bzero(r_buf,1024);
        //open Serial
        open_serial();
        struct timeval tv;
        tv.tv_sec = 1;
        tv.tv_usec = 0;
        struct sockaddr_in server_address;
        struct sockaddr_storage their_addr;
        fdServer = socket(AF_INET,SOCK_STREAM,0);
        if(fdServer<0){ perror("server construct ");return -1;}
        server_address.sin_family = AF_INET;
        server_address.sin_addr.s_addr = htonl(INADDR_ANY);
        server_address.sin_port=htons(SERVERPORT);
        //addr reuse
        int opt = 1;
        setsockopt(fdServer, SOL_SOCKET, SO_REUSEADDR, (const void *)&opt, sizeof(opt));
        if (bind(fdServer, (struct sockaddr*)&server_address, sizeof(server_address)) < 0) { 
            perror("bind:");
            return -1;
        }
        if (listen(fdServer, 10) < 0) { 
            perror("listen:");
            return -1;
        }
        //add serverfd 2 allfdsets
        FD_SET(fdServer, &all_fds);
        if (maxfd < fdServer) maxfd = fdServer;
        while(1)
        { 
            ret = recv_data(fdSerial,r_buf,22);
            if(ret == -1)
                exit(EXIT_FAILURE);
            int i = 0;
            for (i = 0;i < ret;i++) ParseData(r_buf[i]);
            select_fds = all_fds;
            ret = select(maxfd + 1, &select_fds, NULL, NULL, &tv);
            if(ret < 0){ perror("select"); return EXIT_FAILURE;}
            else if(ret == 0){ tv.tv_sec = 0;tv.tv_usec = 20;continue;}
            for(loopIndex = fdServer; loopIndex < maxfd + 1; loopIndex++)
            { 
                if(FD_ISSET(loopIndex, &select_fds)){ 
                    if(loopIndex == fdServer){ 
                        socklen_t addrlen = sizeof(their_addr);
                        int newfd = accept(fdServer, (struct sockaddr *)&their_addr, &addrlen);
                        printf("%d conn", newfd);
                        if(newfd == -1){ 
                            perror("accept:");
                        }else if(newfd >= MAX_FD_NUM){ 
                            fprintf(stderr, "beyond MAX_FD_NUM");
                            close(newfd);
                        }else { 
                            FD_SET(newfd, &all_fds);
                            if (newfd > maxfd) { 
                                maxfd = newfd;
                            }
                        }
                    }else { 
                        int r = client_request(loopIndex);
                        if (r <= 0) { 
                            if (r == 0) { 
                                ;
                            } else { 
                                perror("recv");
                            }
                            close(loopIndex);
                            FD_CLR(loopIndex, &all_fds);
                            if (loopIndex == maxfd) { 
                                maxfd--;
                            }
                        }
                    }
                }
            }
        }
        
    }