Linux serial port programming record (a) serial port parameter setting

Some common serial port properties of the Setup method.

• Set flow control
• Termios_new.c_cflag &= ~crtscts; Do not use flow control
• Termios_new.c_cflag |= crtscts; Using hardware flow control
• Termios_new.c_iflag |= ixon| Ixoff| Ixany; Using Software flow control

• Masked character size bit
• Termios_new.c_cflag &= ~csize;

• Set data bit size
• Termios_new.c_cflag |= CS8; Using 8-bit data bits
• Termios_new.c_cflag |= CS7; Using 7-bit data bits
• Termios_new.c_cflag |= CS6; Using 6-bit data bits
• Termios_new.c_cflag |= CS5; Using 5-bit data bits

• Set parity mode
• Termios_new.c_cflag &= ~parenb; No parity check
• Termios_new.c_cflag |= Parenb; Odd check
• Termios_new.c_cflag &= ~parodd;
• Termios_new.c_cflag |= Parenb; Even check
• Termios_new.c_cflag &= ~parodd;

• Stop bit
• Termios_new.c_cflag |= CSTOPB; 2-bit Stop bit
• Termios_new.c_cflag &= ~CSTOPB; 1-bit stop bit

• Output mode
• Termios_new.c_cflag &= ~opost; Raw data (raw) output

• Control characters
• Termios_new.c_cc[vmin] = 1; Minimum number of characters to read
• Termios_new.c_cc[vtime] = 1; Read the wait time for the first character

• When the terminal echo is turned off, the keyboard input characters are not displayed in the terminal window.
• #include <stdio.h>
• #include <stdlib.h>
• #include <termios.h>
• #include <unistd.h>
• int main (void)
• {
• struct Termios ts,ots;
• Char passbuf[1024];
• Tcgetattr (Stdin_fileno,&ts); /* The value of Stdin_fileno is 1, which represents the file descriptor for standard input */
• ots = ts;
• Ts.c_lflag &= ~echo; /* Turn back terminal echo function */
• Ts.c_lflag |= echonl;
• Tcsetattr (Stdin_fileno,tcsaflush,&ts); /* Apply new terminal settings */
• Fgets (Passbuf,1024,stdin); /* Input characters are not displayed in the terminal */
• printf ("you input character =%s/n", passbuf);
• Tcsetattr (stdin_fileno,tcsanow,&ots); /* Restore the old terminal equipment */

}

Example: Serial port parameter setting function

int Serial::setpara (int serialfd,int speed,int databits, int stopbits, int parity)

{

struct Termios termios_new;

Bzero (&termios_new, sizeof (termios_new));//equivalent to memset (&termios_new,sizeof (termios_new));

Cfmakeraw (&termios_new);//The terminal is set to the original mode

Termios_new.c_cflag=baudrate (speed);

Termios_new.c_cflag |= clocal |   Cread; Termios_new.c_iflag = Ignpar | IGNBRK;

Termios_new.c_cflag &= ~csize;

Switch (databits)

{

Case 0:

Termios_new.c_cflag |= CS5;

Break

Case 1:

Termios_new.c_cflag |= CS6;

Break

Case 2:

Termios_new.c_cflag |= CS7;

Break

Case 3:

Termios_new.c_cflag |= CS8;

Break

Default

Termios_new.c_cflag |= CS8;

Break

}

Switch (parity)

{

Case 0://as no parity

Termios_new.c_cflag &= ~parenb; Clear parity enable

Break

Case 1:

Termios_new.c_cflag |= Parenb; Enable Parity

Termios_new.c_cflag &= ~parodd;

Break

Case 2:

Termios_new.c_cflag |= Parenb;

Termios_new.c_cflag |= ~parodd;

Break

Default

Termios_new.c_cflag &= ~parenb; Clear parity enable

Break

}

Switch (stopbits)//Set Stop Bit

{

Case 1:

Termios_new.c_cflag &= ~CSTOPB;

Break

Case 2:

Termios_new.c_cflag |= CSTOPB;

Break

Default

Termios_new.c_cflag &= ~CSTOPB;

Break

}

Tcflush (Serialfd,tciflush); Clear input Cache

Tcflush (Serialfd,tcoflush); Clear output cache

Termios_new.c_cc[vtime] = 1; The MIN and time combinations have the following four types: 1.MIN = 0, time = 0 has read immediate callback otherwise returns 0, does not read any characters

Termios_new.c_cc[vmin] = 1; 2, MIN = 0, time >0 read back to the reading of the character, or in a very second after the time if it is too late to read any characters, then return 0

Tcflush (SERIALFD, Tciflush); 3, min > 0, Time =0 read will wait until MIN character is readable

Return tcsetattr (serialfd,tcsanow,&termios_new); 4, MIN > 0, Time > 0 The timer between each lattice is started. Read reads the MIN character, returns the value, or

}

int serial::baudrate (int baudrate)
{
Switch (baudrate)
{
Case 0:
return (B2400);
Case 1:
return (B4800);
Case 2:
return (B9600);
Case 3:
return (B19200);
Case 4:
return (B38400);
Case 5:
return (B57600);
Case 6:
return (B115200);
Default
return (B9600);
}
}

Linux serial port programming record (a) serial port parameter setting