I2C温度センサーで室温計測

#include <iostream>
#include <string>
#include <fcntl.h>      // open()
#include <termios.h>    // termios, tcgetattr(), tcsetattr()
#include <unistd.h>     // read(), write(), close()
#include <cstring>      // memset()
#include <errno.h>      // errno

// Function to configure the serial port
bool configureSerialPort(int fd, speed_t baudRate) {
    struct termios tty;
    if (tcgetattr(fd, &tty) != 0) {
        std::cerr << "Error getting terminal attributes: " << strerror(errno) << "\n";
        return false;
    }

    // Set baud rate
    cfsetospeed(&tty, baudRate);
    cfsetispeed(&tty, baudRate);

    // Configure 8N1 (8 data bits, no parity, 1 stop bit)
    tty.c_cflag &= ~PARENB; // No parity
    tty.c_cflag &= ~CSTOPB; // 1 stop bit
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;     // 8 bits per byte

    tty.c_cflag &= ~CRTSCTS; // No hardware flow control
    tty.c_cflag |= CREAD | CLOCAL; // Enable receiver, ignore modem control lines

    // Raw input mode (no processing)
    tty.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    tty.c_iflag &= ~(IXON | IXOFF | IXANY); // No software flow control
    tty.c_oflag &= ~OPOST; // Raw output

    // Set read timeout
    tty.c_cc[VMIN]  = 0;  // Minimum number of characters to read
    tty.c_cc[VTIME] = 10; // Timeout in deciseconds (1s)

    // Apply settings
    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        std::cerr << "Error setting terminal attributes: " << strerror(errno) << "\n";
        return false;
    }
    return true;
}

char* extract(char* input)
{
        char delimiter[] = "\n\n";
        char *start,*end;

        start = strstr(input,delimiter);

        start += 2; // skip \n\n

        end = strstr(start,delimiter);

        if( end )
                *end = '\0';
         else
                return nullptr;

        return start;

}

int main() {
    const char* portName = "/dev/ttyUSB0"; // Change to your serial port
    int fd = open(portName, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        std::cerr << "Error opening " << portName << ": " << strerror(errno) << "\n";
        return 1;
    }

    // Configure the serial port
    if (!configureSerialPort(fd, B9600)) { // Baud rate: 9600
        close(fd);
        return 1;
    }

    // Example: Write data
/*
    std::string outData = "Hello Serial\n";
    int bytesWritten = write(fd, outData.c_str(), outData.size());
    if (bytesWritten < 0) {
        std::cerr << "Error writing to serial port: " << strerror(errno) << "\n";
    } else {
        std::cout << "Sent: " << outData;
    }
*/
    // Example: Read data
    char buffer[256];
char* extdata;

    int bytesRead = read(fd, buffer, sizeof(buffer) - 1);
    if (bytesRead > 0) {
        buffer[bytesRead] = '\0'; // Null-terminate
//        std::cout << "Received: " << buffer << "\n";
        extdata = extract(buffer);
        std::cout << extdata << "\n";
    } else if (bytesRead == 0) {
        std::cout << "No data received (timeout)\n";
    } else {
        std::cerr << "Error reading from serial port: " << strerror(errno) << "\n";
    }

    close(fd);
    return 0;
}