Question

我是嵌入式Linux的新手。我试图在我的芯片上只用UART做一个IR发射器。我设法用单Uart获得38 khz脉冲波。但是为了写出所需的字节来通过红外调整某些东西，我有一些时间问题。例如，我想做1.4 ms逻辑高脉冲和0.5 ms逻辑低（这意味着红外系统的逻辑1帧）所以我的代码就像：

write(fd,buffer,8);  //that means 1.4 ms for pulse to be HIGH
usleep(500);        // 0.5 ms to wait

然后我想写一个字节，如＆＃34; 0xF0＆＃34;所以：

 Byte_Write_For_IRDevice(char byte_v)
 {
    int bitcount;
    char t=0;

    for(bitcount=0;bitcount<8;bitcount++)
    {
      int t=byte_v&1;
      byte_v>>=1;

      if(t==1)        //Logic '1' frame
      {
        write(fd,buffer,8);  //that means 1.4 ms for pulse to be HIGH

        usleep(500);        //0.5 ms for wait
      }
      else            //Logic '0' frame
      {
        write(fd,buffer,4);  //that means 0.7 ms for pulse to be HIGH

        usleep(500);  
      }

   }
 }

当我调用这个函数时，usleep并不能正常工作。我使用nanosleep，posix线程，但它们不能在这里工作是我的openserialport函数下面。我在哪里犯错误？

 int OpenSerialPort()
{

 /* Open and configure serial port */
 if ((fd = open(SERIALPORT,O_RDWR|O_NOCTTY)) == -1)
 {
    return -1;
 }
 struct termios options;
 struct serial_struct serinfo;


 // generating proper Baudrate to obtain 38 Khz freq. pulse wave on Uart
 speed = rate_to_constant(rate);

    if (speed == 0) {
       /* Custom divisor */
       serinfo.reserved_char[0] = 0;
       if (ioctl(fd, TIOCGSERIAL, &serinfo) < 0)
           return -1;
       serinfo.flags &= ~ASYNC_SPD_MASK;
       serinfo.flags |= ASYNC_SPD_CUST;
       serinfo.custom_divisor = (serinfo.baud_base + (rate / 2)) / rate;
       if (serinfo.custom_divisor < 1)
          serinfo.custom_divisor = 1;
       if (ioctl(fd, TIOCSSERIAL, &serinfo) < 0)
          return -1;
       if (ioctl(fd, TIOCGSERIAL, &serinfo) < 0)
          return -1;
       if (serinfo.custom_divisor * rate != serinfo.baud_base) {
              warnx("actual baudrate is %d / %d = %f",
                 serinfo.baud_base, serinfo.custom_divisor,
                 (float)serinfo.baud_base / serinfo.custom_divisor);
       }
   }

   fcntl(fd, F_SETFL, 0);
   tcgetattr(fd, &options);
   cfsetispeed(&options, speed ?: B38400);
   cfsetospeed(&options, speed ?: B38400);
   cfmakeraw(&options);
   options.c_cflag |= (CLOCAL | CREAD);
   options.c_cflag &= ~CRTSCTS;

   if (tcsetattr(fd, TCSANOW, &options) != 0)
   {
    //return -1;
   }


}

Linux串口通信 - 写入时间调整

0 个答案: