Linux串行端口：输入缺少数据 [英] Linux Serial Port: missing data on input
问题描述
#include< fcntl.h>
#include< termios.h>
#include< unistd.h>
#include< errno.h>
#include< cerrno>
#include< iostream>
#include< stdio.h>
#include< stdlib.h>
#include< string.h>
#include< fstream>
#include< sys / types.h>
#include< sys / socket.h>
#include< netinet / in.h>
#include< cstdlib>
#include< ctime>
using namespace std;
typedef struct termios ComSet;
int main（）
{
int acm = -1;
acm = open（/ dev / ttyACM0，O_RDWR | O_NOCTTY）;
if（acm == -1）
{
cout<<Error Opening ttyACM0<< endl;
exit（1）;
}
else
{
cout<<Preparing ttyACM0 ...<< endl;
ComSet SerialSettings;
tcgetattr（acm，& SerialSettings）;
cfsetispeed（& SerialSettings，B9600）;
cfsetospeed（& SerialSettings，B9600）;
/ * 8N1 Mode * /
SerialSettings.c_cflag& =〜PARENB;
SerialSettings.c_cflag& =〜CSTOPB;
SerialSettings.c_cflag& =;〜CSIZE;
SerialSettings.c_cflag | = CS8;
SerialSettings.c_cflag& =〜CRTSCTS;
SerialSettings.c_cflag | = CREAD | CLOCAL;
SerialSettings.c_iflag& =〜（IXON | IXOFF | IXANY）;
SerialSettings.c_iflag& =〜（ICANON | ECHO | ECHOE | ISIG）;
SerialSettings.c_oflag& =;〜OPOST;
/ *设置超时* /
SerialSettings.c_cc [VMIN] = 10; / *读取至少10个字符* /
SerialSettings.c_cc [VTIME] = 0; / *无限等待* /
if（（tcsetattr（acm，TCSANOW，& SerialSettings））！= 0）
{
cout< ERROR！in Setting attributes<< endl;
}
else
{
cout< ======= ttyACM0 Setting =====<< endl;
cout<<BaudRate = 9600 StopBits = 1 Parity = none<< endl;
cout<<Reading ttyACM0 ...<< endl;
char read_buffer [1024];
bzero（read_buffer，1024）;
int read_bytes = 0;
while（1）
{
tcflush（acm，TCIFLUSH）;
read_bytes = read（acm，& read_buffer，1024）;
if（read_bytes> 0）
{
cout<< read_buffer;
bzero（read_buffer，1024）;
}
}
}
close（acm）; / *关闭串口* /
}
return 0;
}
因为某些原因代码它不能正常工作从一个arduino读它工作正常早了它给我grabled输出
如
lo世界！
Hello World！
ello世界！
llo世界！
llo World！
更改的一件事是
输出此为使用cat / dev / ttyAMC0
Hello World！
Hello World！ b
$ b
Hello World！
Hello World！
Hello World！ / p>
我想逐行阅读，因为它是由arduino发送到终端
当你得到乱码输出像 lo World！你好，世界 ！ ello World！那么通常表示你的时钟速度（波特率）不匹配。确保您的Arduino以9600波特的速度写入。
此外，当Arduino输出字符时，它将它们放在硬件缓冲区中。 read（）函数接收您从该缓冲区指定的字节数 - 在这种情况下为1024.但是您可能不想每次读取1024字节。相反，我认为你应该阅读，直到你达到换行字符。查看您使用的库中是否有 readline（）函数。
Linux cat 命令正确读取，但命令本身在末尾添加了一个换行符。
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <errno.h>
#include <cerrno>
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fstream>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <cstdlib>
#include <ctime>
using namespace std;
typedef struct termios ComSet;
int main()
{
int acm=-1;
acm=open("/dev/ttyACM0",O_RDWR | O_NOCTTY);
if(acm == -1)
{
cout<<"Error Opening ttyACM0"<<endl;
exit(1);
}
else
{
cout<<"Preparing ttyACM0..."<<endl;
ComSet SerialSettings;
tcgetattr(acm, &SerialSettings);
cfsetispeed(&SerialSettings,B9600);
cfsetospeed(&SerialSettings,B9600);
/* 8N1 Mode */
SerialSettings.c_cflag &= ~PARENB;
SerialSettings.c_cflag &= ~CSTOPB;
SerialSettings.c_cflag &= ~CSIZE;
SerialSettings.c_cflag |= CS8;
SerialSettings.c_cflag &= ~CRTSCTS;
SerialSettings.c_cflag |= CREAD | CLOCAL;
SerialSettings.c_iflag &= ~(IXON | IXOFF | IXANY);
SerialSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG);
SerialSettings.c_oflag &= ~OPOST;
/* Setting Time outs */
SerialSettings.c_cc[VMIN] = 10; /* Read at least 10 characters */
SerialSettings.c_cc[VTIME] = 0; /* Wait indefinetly */
if((tcsetattr(acm,TCSANOW,&SerialSettings)) != 0)
{
cout<< " ERROR ! in Setting attributes"<<endl;
}
else
{
cout<< "=======ttyACM0 Setting====="<<endl;
cout<<"BaudRate = 9600 StopBits = 1 Parity = none"<<endl;
cout<<"Reading ttyACM0... "<<endl;
char read_buffer[1024];
bzero(read_buffer,1024);
int read_bytes=0;
while(1)
{
tcflush(acm, TCIFLUSH);
read_bytes=read(acm,&read_buffer,1024);
if(read_bytes>0)
{
cout<<read_buffer;
bzero(read_buffer,1024);
}
}
}
close(acm); /* Close the serial port */
}
return 0;
}
for some reason code its not working properly i m trying to read from an arduino as it was working properly earlier its giving me grabled output such as
lo World ! Hello World ! ello World ! llo World ! llo World !
one thing that changed was
there is one extra new line in terminal output this is using cat /dev/ttyAMC0
Hello World !
Hello World !
Hello World !
Hello World !
Hello World !
i want to read line by line and as it was sent by the arduino to terminal
When you get garbled output like lo World ! Hello World ! ello World ! then that usually indicates that your clock speed (baud rate) isn't matched. Make sure your Arduino is writing at a speed of 9600 baud.
Additionally, when the Arduino outputs characters, it puts them in a hardware buffer. The read() function takes the number of bytes you specify out of that buffer- in this case 1024. But you probably don't want to read 1024 bytes every time. Instead, I think you should read until you reach a newline character. See if there is a readline() function in the library you are using.
The Linux cat command is reading correctly, but the command itself adds an extra newline at the end.
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