c语言串口程序

// C library headers
#include <stdio.h>
#include <string.h>// Linux headers
#include <fcntl.h> // Contains file controls like O_RDWR
#include <errno.h> // Error integer and strerror() function
#include <termios.h> // Contains POSIX terminal control definitions
#include <unistd.h> // write(), read(), close()int main() {// Open the serial port. Change device path as needed (currently set to an standard FTDI USB-UART cable type device)int serial_port = open("/dev/ttyUSB0", O_RDWR);// Create new termios struct, we call it 'tty' for conventionstruct termios tty;// Read in existing settings, and handle any errorif(tcgetattr(serial_port, &tty) != 0) {printf("Error %i from tcgetattr: %s\n", errno, strerror(errno));return 1;}tty.c_cflag &= ~PARENB; // Clear parity bit, disabling parity (most common)tty.c_cflag &= ~CSTOPB; // Clear stop field, only one stop bit used in communication (most common)tty.c_cflag &= ~CSIZE; // Clear all bits that set the data sizetty.c_cflag |= CS8; // 8 bits per byte (most common)tty.c_cflag &= ~CRTSCTS; // Disable RTS/CTS hardware flow control (most common)tty.c_cflag |= CREAD | CLOCAL; // Turn on READ & ignore ctrl lines (CLOCAL = 1)tty.c_lflag &= ~ICANON;tty.c_lflag &= ~ECHO; // Disable echotty.c_lflag &= ~ECHOE; // Disable erasuretty.c_lflag &= ~ECHONL; // Disable new-line echotty.c_lflag &= ~ISIG; // Disable interpretation of INTR, QUIT and SUSPtty.c_iflag &= ~(IXON | IXOFF | IXANY); // Turn off s/w flow ctrltty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL); // Disable any special handling of received bytestty.c_oflag &= ~OPOST; // Prevent special interpretation of output bytes (e.g. newline chars)tty.c_oflag &= ~ONLCR; // Prevent conversion of newline to carriage return/line feed// tty.c_oflag &= ~OXTABS; // Prevent conversion of tabs to spaces (NOT PRESENT ON LINUX)// tty.c_oflag &= ~ONOEOT; // Prevent removal of C-d chars (0x004) in output (NOT PRESENT ON LINUX)tty.c_cc[VTIME] = 10;    // Wait for up to 1s (10 deciseconds), returning as soon as any data is received.tty.c_cc[VMIN] = 0;// Set in/out baud rate to be 9600cfsetispeed(&tty, B9600);cfsetospeed(&tty, B9600);// Save tty settings, also checking for errorif (tcsetattr(serial_port, TCSANOW, &tty) != 0) {printf("Error %i from tcsetattr: %s\n", errno, strerror(errno));return 1;}// Write to serial portunsigned char msg[] = { 'H', 'e', 'l', 'l', 'o', '\r' };write(serial_port, msg, sizeof(msg));// Allocate memory for read buffer, set size according to your needschar read_buf [256];// Normally you wouldn't do this memset() call, but since we will just receive// ASCII data for this example, we'll set everything to 0 so we can// call printf() easily.memset(&read_buf, '\0', sizeof(read_buf));// Read bytes. The behaviour of read() (e.g. does it block?,// how long does it block for?) depends on the configuration// settings above, specifically VMIN and VTIMEint num_bytes = read(serial_port, &read_buf, sizeof(read_buf));// n is the number of bytes read. n may be 0 if no bytes were received, and can also be -1 to signal an error.if (num_bytes < 0) {printf("Error reading: %s", strerror(errno));return 1;}// Here we assume we received ASCII data, but you might be sending raw bytes (in that case, don't try and// print it to the screen like this!)printf("Read %i bytes. Received message: %s", num_bytes, read_buf);close(serial_port);return 0; // success
};