將十六進制發送到xbee無線電模塊

Question

我目前正在嘗試將十六進制命令發送到xbee無線電模塊（API模式）。

這是我的代碼：

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <iostream>

using namespace std;

int main()
{

   int fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);


   if (fd < 0 ){
       cout << "Error " << errno << " opening /dev/ttyUSB0: " << strerror(errno) << endl;
   }    
   else
   {
       struct termios tty;
       struct termios tty_old;
       memset (&tty, 0, sizeof tty);

       if (tcgetattr (fd, &tty) != 0){
           cout << "Error " << errno << " from tcgetattr: " << strerror (errno) << endl;
       }

       tty_old = tty;

       cfsetispeed(&tty, B57600);
       cfsetospeed(&tty, B57600);

       tty.c_cflag &= ~PARENB;
       tty.c_cflag &= ~CSTOPB;
       tty.c_cflag &= ~CSIZE;
       tty.c_cflag |= CS8;
       tty.c_cflag &= ~CRTSCTS;
       tty.c_lflag = 0;
       tty.c_oflag = 0;
       tty.c_cc[VMIN] = 1;
       tty.c_cc[VTIME] = 50;

       tty.c_cflag |= CREAD | CLOCAL;

       cfmakeraw(&tty);

       tcflush(fd, TCIFLUSH);

       if (tcsetattr(fd, TCSANOW, &tty) != 0) {
           cout << "Error " << errno << " from tcsetattr" << endl;
       }

       unsigned char cmd1[] = {"\0x7E\0x00\0x04\0x08\0x69\0x43\0x54\0xF7"};

       sleep(1);
       int wr1 = write(fd, cmd1, 8);
       sleep(1);

       int rd;
       int spot = 0;
       char buff = '\0';


       char resp[128];
       memset(resp, '\0', sizeof(resp));

       do {
           rd = read(fd, &buff, 1);
           sprintf(&resp[spot], "%c", buff);
           spot += rd;
       } while (buff != '\r' && rd > 0);
       if (rd<0){
           cout << "Error reading: " << strerror(errno) << endl;
       }
       else if (rd==0) {
           cout << "Read nothing!" << endl;
       }
       else {
           cout << "Read: " << resp << endl;
       }

       close(fd);

    }
    return 0;
}

我也這樣嘗試過：

    unsigned char cmd1[8];

    cmd1[0] = 0X7E;
    cmd1[1] = 0X00;
    cmd1[2] = 0X04;
    cmd1[3] = 0X08;
    cmd1[4] = 0X69;
    cmd1[5] = 0X43;
    cmd1[6] = 0X54;
    cmd1[7] = 0XF7;


    sleep(1);
    int wr1 = write(fd, cmd1, 8);

當我使用AT命令模式時，它工作得非常好，這是在AT命令模式下執行完全相同的代碼（詢問蜜蜂在“ +++”之后在命令模式下持續多長時間）：

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <unistd.h>
#include <stdlib.h>
#include <iostream>

using namespace std;

int main()
{

int fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);


if (fd < 0 ){
    cout << "Error " << errno << " opening /dev/ttyUSB0: " << strerror(errno) << endl;
}   
else
{
    struct termios tty;
    struct termios tty_old;
    memset (&tty, 0, sizeof tty);

    if (tcgetattr (fd, &tty) != 0){
        cout << "Error " << errno << " from tcgetattr: " << strerror (errno) << endl;
    }

    tty_old = tty;

    cfsetispeed(&tty, B57600);
    cfsetospeed(&tty, B57600);

    tty.c_cflag &= ~PARENB;
    tty.c_cflag &= ~CSTOPB;
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;
    tty.c_cflag &= ~CRTSCTS;
    tty.c_lflag = 0;
    tty.c_oflag = 0;
    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 50;

    tty.c_cflag |= CREAD | CLOCAL;

    cfmakeraw(&tty);

    tcflush(fd, TCIFLUSH);

    if (tcsetattr(fd, TCSANOW, &tty) != 0) {
        cout << "Error " << errno << " from tcsetattr" << endl;
    }

    unsigned char cmd1[] = {"+++"};
    sleep(1);
    int wr1 = write(fd, cmd1, sizeof(cmd1) -1);
    sleep(1);
    //printf("%d \n", wr1);
    unsigned char cmd2[] = {"ATCT\r"};

    int rd;
    int spot = 0;
    char buff = '\0';

    char resp[32];
    memset(resp, '\0', sizeof(resp));

    do {
        rd = read(fd, &buff, 1);
        sprintf(&resp[spot], "%c", buff);
        spot += rd;
    } while (buff != '\r' && rd > 0);
    if (rd<0){
        cout << "Error reading: " << strerror(errno) << endl;
    }
    else if (rd==0) {
        cout << "Read nothing!" << endl;
    }
    else {
        cout << "Read: " << resp << endl;
    }


    int wr2 = write(fd, cmd2, sizeof(cmd2) -1);
    //printf("%d \n", wr2);

    spot = 0;
    buff = '\0';


    sleep(1);
    do {
        rd = read(fd, &buff, 1);
        sprintf(&resp[spot], "%c", buff);
        spot += rd;
    } while (buff != '\r' && rd > 0);
    if (rd<0){
        cout << "Error reading: " << strerror(errno) << endl;
    }
    else if (rd==0) {
        cout << "Read nothing!" << endl;
    }
    else {
        cout << "Read: " << resp << endl;
    }
    close(fd);

    }
    return 0;
}

我得到的錯誤是

“錯誤讀取：資源暫時不可用”。

我確定該設備沒有被其他人使用，因為使用AT命令的代碼可以正常工作...好像Xbee無法理解十六進制...

我希望其他人已經遇到了這個問題...

Answer 1

好的，所以有點古怪...

我試圖閱讀一個以\\ r結尾的答案，但真正的答案還沒有完成...

我改變：

do {
    rd = read(fd, &buff, 1);
    sprintf(&resp[spot], "%c", buff);
    spot += rd;
} while (buff != 0x13 && rd > 0);

現在工作正常。 就像試圖讀取不存在的字符一樣。

編輯：

@VenushkaT問我一個有關此代碼中某些問題的問題。 由於我現在所做的事情在prerry上都能正常工作，因此我發布了新代碼：

void R1logger::listenPort()
{
// Creation of a buffer to store data from radio module

fill_n(buff, 2048, '\0');

this->ind = 0;

while(this->fd > 0)
{
    // Creation of a buffer that stores data from serial port
    char mes[1024];
    fill_n(mes, 1024, '0');
    // read is a blocking call so this function will not return until it effectively reads some data or if there is a problem
    int rd = read(this->fd, &mes, sizeof(mes));

    /*struct timeval tv;
    gettimeofday(&tv, NULL);
    unsigned long long check1 = (unsigned long long)(tv.tv_sec) * 1000 + (unsigned long long)(tv.tv_usec) / 1000;*/
    if (rd > 0)
    {
        storeInBuff(mes, rd);
        fill_n(mes, 1024, '0');

        // If some data are read, we can have only a part of the frame so we call "poll" to wait for the rest of the data with a 10ms timeout
        struct pollfd fds;
        fds.fd = this->fd;
        fds.events = POLLIN | POLLPRI;
        int slct = 1;

        while (slct > 0)
        {
            slct = poll(&fds, 1, 10);
            if (slct > 0)
            {
                rd = read(this->fd, &mes, sizeof(mes));
                if (rd > 0)
                {
                    storeInBuff(mes, rd);
                }
                else
                {
                    close(this->fd);
                    serialConfig();
                }
            }
        }

        /*gettimeofday(&tv, NULL);
        unsigned long long check2 = (unsigned long long)(tv.tv_sec) * 1000 + (unsigned long long)(tv.tv_usec) / 1000;
        unsigned long tmps = check2 - check1;
        cout << "Temps de lecture : " << tmps << endl;*/

        /*gettimeofday(&tv, NULL);
        check1 = (unsigned long long)(tv.tv_sec) * 1000 + (unsigned long long)(tv.tv_usec) / 1000;*/

        // Once the message is entirely read, we extract the radio frames
        findFrame(0);

        /*gettimeofday(&tv, NULL);
        check2 = (unsigned long long)(tv.tv_sec) * 1000 + (unsigned long long)(tv.tv_usec) / 1000;
        tmps = check2 - check1;
        cout << "Temps calcul + ecriture sur disque : " << tmps << endl;*/


        this->ind = 0;
        fill_n(buff, 2048, '\0');
    }
    else
    {
        close(this->fd);
        serialConfig();
    }
}
}

由於存在阻塞調用（讀取，選擇）且未設置O_NONBLOCKING選項，因此此代碼使用的CPu較少。 我還考慮了讀取失敗的情況。

在另一篇文章中，有人向我提出關於串行配置的建議（某些選項存在一些錯誤，他們給了我建議以更符合POSIX，所以這里是：

void R1logger::serialConfig()
{

// Open Serial Port

this->fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY);

if (this->fd < 0 )
{
    cout << "Error " << errno << " opening /dev/ttyUSB0: " << strerror(errno) << endl;
}
else
{
    //Configure Serial Port
    struct termios tty;

    if (tcgetattr (this->fd, &tty) != 0)
    {
        cout << "Error " << errno << " from tcgetattr: " << strerror (errno) << endl;
    }

    cfsetispeed(&tty, B57600);
    cfsetospeed(&tty, B57600);

    tty.c_cflag &= ~PARENB;
    tty.c_cflag &= ~CSTOPB;
    tty.c_cflag &= ~CSIZE;
    tty.c_cflag |= CS8;
    tty.c_cc[VMIN] = 1;
    tty.c_cc[VTIME] = 50;

    tty.c_cflag |= CREAD | CLOCAL;

    cfmakeraw(&tty);

    tcflush(this->fd, TCIFLUSH);

    if (tcsetattr(this->fd, TCSANOW, &tty) != 0) 
    {
        cout << "Error " << errno << " from tcsetattr" << endl;
    }
}
}