嵌入式Linux下串口编程
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。