串口设备：读8N1的作品，但是写一个字节失败 [英] Serial Device: Reading 8N1 works, but writing a single byte fails

问题描述

在我的节目，我从串行设备（Linux操作系统，8N1）没有任何问题读取。但在情况下，我想写出一个字节，我得到什么了接口。我以为我的串行输出的设置是错误的。但是有没有那么多的方式如何设置c_oflag定义...

In my program I read from the serial device (Linux, 8N1) without any problem. But in the case I want to write out a single byte, I get nothing out on the interface. I assume that my serial output settings are wrong. But there aren't that many ways how to set c_oflag...

我的code：

#define TTYDEVICE "/dev/ttyS0"
#define BAUDRATE B9600

int openSerialDevice(const char* devTTY, struct termios oldTio) {
//----< Open serial device >----------------------------------
int fileDescriptor;
// fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
fileDescriptor = open(devTTY, O_RDWR | O_NOCTTY);
//fileDescriptor = open(devTTY, O_RDWR | O_NOCTTY /*| OPOST*/);
if (fileDescriptor == -1) {
    perror("Error while opening serial interface occurred!");
    return -99;
}

// set new parameters to the serial device
struct termios newtio;
bzero(&newtio, sizeof(newtio));
newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;

// set to 8N1
newtio.c_cflag &= ~PARENB;
newtio.c_cflag &= ~CSTOPB;
newtio.c_cflag &= ~CSIZE;
newtio.c_cflag |= CS8;

newtio.c_iflag = IGNPAR;

// output mode to
//newtio.c_oflag = 0;
newtio.c_oflag |= OPOST;

/* set input mode (non-canonical, no echo,...) */
newtio.c_lflag = 0;

newtio.c_cc[VTIME] = 10; /* inter-character timer 1 sec */
newtio.c_cc[VMIN] = 0; /* blocking read disabled  */

tcflush(fileDescriptor, TCIFLUSH);
if (tcsetattr(fileDescriptor, TCSANOW, &newtio)) {
    perror("could not set the serial settings!");
    return -99;
}

//----< / Open serial device >----------------------------------
return fileDescriptor;
}

int ACK[1] = { 6 };

int main() {
// old termios to restablish
struct termios oldTIO;
// filedescriptor
int fd;

fd = openSerialDevice(TTYDEVICE, oldTIO);

if ((fd == -1) | (fd == -99)) {
    perror("Could not open TTY-Device. Exit on failure!");
    return EXIT_FAILURE;
}

write(fd, ACK, 1);  // Problem !! 


     return 0:
}

现在，如果我用

屏幕上的/ dev / 9600就是ttyS1 8N1

screen /dev/ttyS1 9600 8n1

要验证什么现身在/ dev / ttyS0来。我什么都看不到。同样的，如果我用嗅探1.8 Docklight。

to verify what's coming out on /dev/ttyS0. I can't see anything. Same if I sniff with Docklight 1.8.

有什么建议？谢谢

推荐答案

如何验证什么都不出来？

How do you verify nothing is coming out ?

您可以尝试删除该RTSCTS，然后再试一次。逸岸，如果你想从tty层最小的干扰，您应将终端设置为原料，采用这样的：

You can try to drop the RTSCTS, and try again. Infact, if you want minimal interference from the tty layer, you should set your terminal to raw, using this :

cfmakeraw(&newtio);

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