为什么串行端口在发送数据时跳过数据

我已经编写了一些C++代码，可以通过串行方式与我的arduino对话。它只是试图使用正弦和余弦在两个伺服电机上产生振荡，但它跳过了数据。我不知道为什么会发生这种事。我在用termios.h做连续剧。C++的输出类似于"V180H90"，即垂直180，水平90。我以前使用fstream和usleep（）发送数据，它很有效，但我想使用一种比延迟任意数字更好的方法。

感谢您的帮助或指导。

我的arduino代码

#include <Servo.h>
typedef enum { NONE, GOT_V, GOT_H } states;
states state = NONE;
Servo pan;
Servo tilt;
int laser = 11;
unsigned int currentValue;
int v_pan = 0;
int v_tilt = 0;
void setup()
{
  pan.attach(10);
  tilt.attach(9);
  Serial.begin(9600);
  state = NONE;
}
void processVertical(const unsigned int value)
{
  Serial.print("Vertical = ");
  Serial.println(value);
  int result = 1300 + (value - 90) * 2;
  //Serial.println(result);
  tilt.writeMicroseconds(result);
}
void processHorizontal(const unsigned int value)
{
  Serial.print("Horizontal = ");
  Serial.println(value);
  int result = 1500 + (value - 180) * 1;
  //Serial.println(result);
  pan.writeMicroseconds(result);
}
void handlePreviousState()
{
  switch(state)
  {
    case GOT_V:
      processVertical(currentValue);
      break;
    case GOT_H:
      processHorizontal(currentValue);
      break;
  }
  currentValue = 0;
}
void processIncomingByte (const byte c)
{
  if (isdigit(c))
  {
    currentValue *=10;
    currentValue += c - '0';
  }
  else
  {
    handlePreviousState();
    switch (c)
    {
      case 'V':
        state = GOT_V;
        break;
      case 'H':
        state = GOT_H;
        break;
      default:
        state = NONE;
        break;
    }
  }
}
void loop()
{
  if(Serial.available() > 0) 
  { 
    processIncomingByte(Serial.read());
  } 
  digitalWrite(laser, HIGH);
}
//check out writeMicroseconds

我的C++代码

// Program for sending data to serial
#include <iostream>
#include <sstream>
#include <string>
#include <termios.h>
#include <fcntl.h>
#include <math.h>
using namespace std;
//open serial port
int openPort(string path)
{
  int fd; //file descriptor for port
  fd = open(path.c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
  if (fd == -1)
    cerr << "Cannot open port" << endl;
  else
    fcntl(fd, F_SETFL, 0);
  return (fd);
}
//set options for an open serial port
void setOptions(int fd)
{
  struct termios options;
  tcgetattr(fd, &options);
  cfsetispeed(&options, B9600);
  cfsetospeed(&options, B9600);
  //No parity 8N1
  options.c_cflag &= ~PARENB;
  options.c_cflag &= ~CSTOPB;
  options.c_cflag &= ~CSIZE;
  options.c_cflag |= CS8;
  //No flow control
  options.c_cflag &= ~CRTSCTS;
  //Turn off s/w flow control
  options.c_iflag &= ~(IXON | IXOFF | IXANY);
  //Turn on read and ignore ctrl lines
  options.c_cflag |= (CLOCAL | CREAD); 
  if( tcsetattr(fd, TCSANOW, &options) < 0) { 
    cerr << "Could not set attributes" << endl; 
  }
}
//write to serial port
void writePort(int fd, string data)
{
  int n = write(fd, data.c_str(), 9);
  if (n < 0)
    cerr << "Cannot write to port" << endl;
}
int main() {
  string path = "/dev/tty.usbmodemfd131";
  //string path = "/dev/tty.usbmodemfa141";
  int fd = openPort(path);
  setOptions(fd);
  stringstream ss;
  string output;
  unsigned short vertical = 0;
  unsigned short horizontal = 0; 
  unsigned short freq = 10;
  for(int i = 0; i < 360; i++) {
    vertical = ((cos(i * freq * ((M_PI)/180))) + 1) * 90;
    horizontal = ((sin(i * freq * ((M_PI)/180))) + 1) * 90;
    ss << "V" << vertical << "H" << horizontal << endl; 
    output = ss.str();
    ss.str("");
    writePort(fd, output);
//    cout << output; //DEBUG
  }
  close(fd);
  return 0;
}