嵌入式

嵌入式Linux下串口编程(一)

2019-07-12 14:26发布

站内文章 / 嵌入式Linux
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嵌入式Linux下串口编程 一、配置内核 在嵌入式Linux下进行串口编程之前，先在内核中配置串口部分，如下： Device Drivers--->        character devices--->               Serial drivers--->                      <*>Samssung S3C2440/S3C2442 Serial port support 二、应用程序 C文件： uart_init.c:打开设备、初始化串口(设置参数) main.c:测试串口读写 头文件： uart_init.h Makfile     uart_init.c #include #include #include #include #include #include #include #include #include   int open_termios(char *dev) {        int fd = -1;        if(-1 == (fd = open(dev,O_RDWR|O_NOCTTY|O_NONBLOCK)))        {               printf("open termios error!/n");        }        return fd; }   int set_termios(int fd,long speed,char databit,char stopbit,char oebit) {        struct termios newtio;        int err = -1;               //清零结构体        bzero(&newtio,sizeof(newtio));        //设置接收使能        newtio.c_cflag |= CLOCAL | CREAD;        // 设置数据位        switch(databit)        {               case 7:                      newtio.c_cflag |= CS7;                      break;               case 8:                      newtio.c_cflag |= CS8;                      break;               default:                      newtio.c_cflag |= CS8;                      break;        }        //设置停止位        switch(stopbit)        {               case 1:                      newtio.c_cflag &= ~CSTOPB;                      break;               case 2:                      newtio.c_cflag |= CSTOPB;                      break;               default:                      newtio.c_cflag &= ~CSTOPB;                      break;        }        //设置校验位        switch(oebit)        {               case 'O':    //奇校验                      newtio.c_cflag |= PARENB;                      newtio.c_cflag |= (INPCK | ISTRIP);                      newtio.c_cflag |= PARODD;                      break;               case 'E':    //偶数                      newtio.c_cflag |= PARENB;                      newtio.c_cflag |= (INPCK | ISTRIP);                      newtio.c_cflag &= ~PARODD;                      break;               case 'N':    //不校验                      newtio.c_cflag &= ~PARODD;                      break;               default:                       //不校验                      newtio.c_cflag &= ~PARODD;                      break;        }        //设置波特率        switch(speed)        {               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 57600:                      cfsetispeed(&newtio,B57600);                      cfsetospeed(&newtio,B57600);                      break;                   case 115200:                      cfsetispeed(&newtio,B115200);                      cfsetospeed(&newtio,B115200);                      break;                   default:                      cfsetispeed(&newtio,B9600);                      cfsetospeed(&newtio,B9600);                      break;            }        //设置等待时间和最小接收字符数        newtio.c_cc[VTIME] = 0;        newtio.c_cc[VMIN] = 0;        //处理未接收字符        tcflush(fd,TCIFLUSH);        //激活配置        if((tcsetattr(fd,TCSANOW,&newtio)) != 0)               perror("com set error!");        else               err = 0;        perror("com set done!");        return err; }     uart_init.h #ifndef __UART_INIT__ #define __UART_INIT__ extern int open_termios(char *dev); int set_termios(int fd,long speed,char databit,char stopbit,char oebit); #endif     main.c #include #include #include #include #include #include #include #include "uart_init.h"   char *uart0_dev="/dev/ttySAC0";   int main(void) {        int uart0_fd;        int err = 0;        char uart0_byte = 0;             char *uart0_buff[8]={0};          uart0_fd = open_termios(uart0_dev);        if(uart0_fd < 0)        {               exit(1);        }        do        {               err = set_termios(uart0_fd,115200,8,1,'N');        }        while(-1 == err);        while(1)        {               read(uart0_fd,&uart0_byte,1);               if(0xfd == uart0_byte)                        {                      read(uart0_fd,uart0_buff,8);                      write(uart0_fd,uart0_buff,8);                      memset(uart0_buff,0,sizeof(uart0_buff));                      uart0_byte = 0;               }                                 }        exit(0); }     Makefile #You can add source code file like the following SOURCE += main.c SOURCE += uart_init.c   ##You can add header code file like the following HEADER += uart_init.h     #You can name the executable file like the following TARGET = UART_ARM   #You can add include path like the following INCLUDEPATH = #You can library path like the following LIBPATH = #You can add library like the following LIBS = -lpthread     #You cant add compile options like the following OPTION += -Wall  OPTION += -g   #You can specify the compiler CC=arm-linux-gcc   #Don't modify the following code unless you know howto exactly OBJECTS =$(SOURCE:%.c=%.o)   $(TARGET):$(OBJECTS)        $(CC) $(OPTION) $(INCLUDEPATH) $(LIBPATH) $(LIBS) -o $(TARGET) $(OBJECTS) clean:        -rm -f $(TARGET) *.o *~ 在串口调试助手选择波特率，选择十六进制显示并打开串口后，发送“fd 31 32 33 34 35 36 37 38”这串十六进制数据后，接收端就出现“31 32 33 34 35 36 37 38”数据。  

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