导:学习过单片机的用户,对串口不会太陌生,在单片机串口编程中,需要用户直接对寄存器以及中断进行控制。
而在 linux 串口编程中,无论是从 linux 官方直接下载的原生态内核,还是任何厂家提供的linux 内核,都会将串口驱动写好,所以对于所有的驱动工程师来说,是完全不需要自己动手写串口驱动的。
串口的编程:
1.初始化:配置波特率,数据位,校验位
首先定义一个初始化函数
int set_opt(int fd,int nSpeed, int nBits, char nEvent, int nStop)。
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; newtio.c_cflag &= ~CSIZE; switch( nBits ) { case 7: newtio.c_cflag |= CS7; break; case 8: newtio.c_cflag |= CS8; break; } switch( nEvent ) { case 'O': newtio.c_cflag |= PARENB; newtio.c_cflag |= PARODD; newtio.c_iflag |= (INPCK | ISTRIP); 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; 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(fd,TCIFLUSH); if((tcsetattr(fd,TCSANOW,&newtio))!=0) { perror("com set error"); return -1; } printf("串口设置完成!\n\r"); return 0; }
2.串口收发测试
#include <string.h> #include <stdio.h> #include <unistd.h> #include <fcntl.h> #include <stdlib.h> #include <sys/types.h> #include <termios.h> #include <sys/stat.h> #include <sys/stat.h> #include <fcntl.h> #include <termios.h> #include <errno.h> int set_opt(int ,int , int , char , int ); void main() { int fd,nByte; char *uart3 = "/dev/ttySAC3"; char *uart_out="请输入:\n"; char buff[512]; memset(buff,0,sizeof(buff)); if((fd=open(uart3,O_RDWR | O_NOCTTY))<0) { printf("打开失败\n"); }else { set_opt(fd,115200,8,'N',1); write(fd,uart_out,strlen(uart_out)); while(1) { while((nByte=read(fd,buff,512))>0) { buff[nByte+1]='\0'; write(fd,buff,strlen(buff)); memset(buff,0,strlen(buff)); nByte=0; } } } }3.验证通过!!!