/*********************************************************************************
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* Copyright: (C) 2024 LingYun IoT System Studio
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* All rights reserved.
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*
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* Filename: ttyS_test.c
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* Description: This file is comport loop back test program
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*
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* Version: 1.0.0(05/24/2024)
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* Author: Guo Wenxue <guowenxue@gmail.com>
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* ChangeLog: 1, Release initial version on "05/24/2024 07:38:43 PM"
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*
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********************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <termios.h>
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#include <pthread.h>
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#define DEV_NAME "/dev/ttymxc1"
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#define MSG "Hello, LingYun IoT System Studio!"
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int main(int argc, char **argv)
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{
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struct termios tty;
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int serial_fd;
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int bytes;
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char read_buf[64];
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/*+-------------------------+
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| Open Serial Port |
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+-------------------------+*/
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serial_fd = open(DEV_NAME, O_RDWR );
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if (serial_fd == -1)
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{
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printf("Open '%s' failed: %s\n", DEV_NAME, strerror(errno));
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return 0;
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}
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/*+-------------------------+
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| Configure Serial Port |
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+-------------------------+*/
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tcgetattr(serial_fd, &tty);// read current serial port settings
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tty.c_cflag &= ~PARENB; // Clear parity bit, disabling parity (most common)
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tty.c_cflag &= ~CSTOPB; // Clear stop field, only one stop bit used in communication (most common)
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tty.c_cflag &= ~CSIZE; // Clear all bits that set the data size
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tty.c_cflag |= CS8; // 8 bits per byte (most common)
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tty.c_cflag &= ~CRTSCTS; // Disable RTS/CTS hardware flow control (most common)
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tty.c_cflag |= CREAD | CLOCAL; // Turn on READ & ignore ctrl lines (CLOCAL = 1)
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tty.c_lflag &= ~ICANON;
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tty.c_lflag &= ~ECHO; // Disable echo
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tty.c_lflag &= ~ECHOE; // Disable erasure
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tty.c_lflag &= ~ECHONL; // Disable new-line echo
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tty.c_lflag &= ~ISIG; // Disable interpretation of INTR, QUIT and SUSP
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tty.c_iflag &= ~(IXON | IXOFF | IXANY); // Turn off s/w flow ctrl
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tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP|INLCR|IGNCR|ICRNL); // Disable any special handling of received bytes
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tty.c_oflag &= ~OPOST; // Prevent special interpretation of output bytes (e.g. newline chars)
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tty.c_oflag &= ~ONLCR; // Prevent conversion of newline to carriage return/line feed
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tty.c_cc[VTIME] = 10; // Wait for up to 1s (10 deciseconds), returning as soon as any data is received.
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tty.c_cc[VMIN] = 0;
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/* Set in/out baud rate to be 115200 */
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cfsetispeed(&tty, B115200);
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cfsetospeed(&tty, B115200);
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tcsetattr(serial_fd, TCSANOW, &tty);
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/*+-------------------------+
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| Write to Serial Port |
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+-------------------------+*/
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write(serial_fd, MSG, strlen(MSG));
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printf("Send MSG : %s\n", MSG);
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/*+-------------------------+
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| Read from Serial Port |
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+-------------------------+*/
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/*
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* The behaviour of read() (e.g. does it block?, how long does it block for?)
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* depends on the configuration settings above, specifically VMIN and VTIME
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*/
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memset(&read_buf, '\0', sizeof(read_buf));
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bytes = read(serial_fd, &read_buf, sizeof(read_buf));
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if (bytes< 0)
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{
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printf("Error reading: %s", strerror(errno));
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goto cleanup;
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}
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printf("Received MSG: %s\n", read_buf);
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/*+-------------------------+
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| close Serial Port |
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+-------------------------+*/
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cleanup:
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close(serial_fd);
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return 0; // success
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}
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