Question

亲爱的同事们。我正在尝试为Linux编写C程序来编写串口（Arduino）并等待回答。我知道，在论坛上有很多关于它的问题，但我尝试的都有同样的问题 - 成功写 - 但不是读回答。例如，here和here。我找到了write和read两个单独的文件。

我在一个终端窗口中编译并运行读取文件，并在另一个终端窗口中编写文件。效果很好。但我无法将它们合并到一个文件中进行写入，然后等待回答。同样的问题 - 写，但不读。

这就像我试过的那样：

#include <stdio.h>
#include <fcntl.h>
#include <termios.h>
#include <unistd.h>
#include <errno.h>
void main(void)
{
int fd;
fd = open("/dev/ttyS0",O_RDWR | O_NOCTTY | O_SYNC); 
if(fd == -1)
       printf("\n  Error! in Opening ttyUSB0  ");
else
       printf("\n  ttyS0 Opened Successfully ");
struct termios SerialPortSettings;  
tcgetattr(fd, &SerialPortSettings);
cfsetispeed(&SerialPortSettings,B9600);
cfsetospeed(&SerialPortSettings,B9600);
        /* 8N1 Mode */
SerialPortSettings.c_cflag &= ~PARENB; 
SerialPortSettings.c_cflag &= ~CSTOPB;
SerialPortSettings.c_cflag &= ~CSIZE;
SerialPortSettings.c_cflag |=  CS8;
SerialPortSettings.c_cflag &= ~CRTSCTS; 
SerialPortSettings.c_cflag |= CREAD | CLOCAL;
SerialPortSettings.c_iflag &= ~(IXON | IXOFF | IXANY);
SerialPortSettings.c_iflag &= ~(ICANON | ECHO | ECHOE | ISIG);
SerialPortSettings.c_oflag &= ~OPOST;/*No Output Processing*/
        /* Setting Time outs */
SerialPortSettings.c_cc[VMIN] = 10; /* Read at least 10 characters */
SerialPortSettings.c_cc[VTIME] = 0; /* Wait indefinetly   */
if((tcsetattr(fd,TCSANOW,&SerialPortSettings)) != 0)
    printf("\n  ERROR ! in Setting attributes");
else
    printf("\n  BaudRate = 9600 \n  StopBits = 1 \n  Parity   = none");

char write_buffer[] = "Hello/n";
int  bytes_written  = 0;
printf("\n  %s written to ttyUSB0",write_buffer);
printf("\n  %d Bytes written to ttyUSB0", bytes_written);
printf("\n +----------------------------------+\n\n");          
//tcflush(fd, TCIFLUSH); /* Discards old data in the rx buffer            */
char read_buffer[32];
int  bytes_read = 0;
int i = 0;

write(fd,write_buffer,sizeof(write_buffer));/* use write() to send data to port   */
usleep ((8 + 25) * 100);            /* Delay */
read(fd,&read_buffer,32);            /* Read the data                   */
printf("\n\n  Bytes Rxed -%d", bytes_read); /* Print the number of bytes read */
printf("\n\n  ");
for(i=0;i<bytes_read;i++)    /*printing only the received characters*/
        printf("%c",read_buffer[i]);
printf("\n +----------------------------------+\n\n\n");
close(fd); /* Close the serial port */
}

感谢您的帮助，祝您度过愉快的一天。

Answer 1

您有一个名为bytes_read的变量，初始化为0。代码中的任何内容都不会更改该值。 - user3386109

声明read(fd,&read_buffer,32)应更正为bytes_read = read(fd, read_buffer, 32) ... - 木屑

Linux C写串口（Arduino）并等待回答

1 个答案: