c++与Arduino串行通信

我正在研究一个在Windows PC和Arduino Uno卡之间进行串行通信的项目。

在c++代码中我有一个SerialClass.h和一个Serial.cpp

我的问题是，我得到一个编译器错误:标识符"SP"未定义在函数

void Serial::SendtoArd(int val, int var)
{
if (SP->IsConnected())
{
    bool writeData = false;
    writeData = SP->WriteData("test",4);
}

我知道如果我在这个函数中定义SP我就能摆脱这个错误，但是我不想激活该功能中的串行端口。我想激活这个函数中的串口

bool Serial::OpenPtoArd()
{
Serial* SP = new Serial("\\.\COM3");    // adjust as needed
if (SP->IsConnected())
{
    bool status = true;
}
}

并保持激活，只要我的应用程序正在运行。

这里是SerialClass.h

#ifndef SERIALCLASS_H_INCLUDED
#define SERIALCLASS_H_INCLUDED
#define ARDUINO_WAIT_TIME 2000
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
class Serial
{
private:
//Serial comm handler
HANDLE hSerial;
//Connection status
bool connected;
//Get various information about the connection
COMSTAT status;
//Keep track of last error
DWORD errors;
public:
//Initialize Serial communication with the given COM port
Serial(char *portName);
//Close the connection
~Serial();
//Read data in a buffer, if nbChar is greater than the
//maximum number of bytes available, it will return only the
//bytes available. The function return -1 when nothing could
//be read, the number of bytes actually read.
int ReadData(char *buffer, unsigned int nbChar);
//Writes data from a buffer through the Serial connection
//return true on success.
bool WriteData(char *buffer, unsigned int nbChar);
//Check if we are actually connected
bool IsConnected();
bool OpenPtoArd();
void SendtoArd(int val, int var);

};

这里是Serial.cpp

#endif // SERIALCLASS_H_INCLUDED

#include "stdafx.h"
#include "SerialClass.h"

#define LEN 1
bool status = false;
Serial::Serial(char *portName)
{
//We're not yet connected
this->connected = false;
//Try to connect to the given port throuh CreateFile
this->hSerial = CreateFile(portName,
    GENERIC_READ | GENERIC_WRITE,
    0,
    NULL,
    OPEN_EXISTING,
    FILE_ATTRIBUTE_NORMAL,
    NULL);
//Check if the connection was successfull
if (this->hSerial == INVALID_HANDLE_VALUE)
{
    //If not success full display an Error
    if (GetLastError() == ERROR_FILE_NOT_FOUND) {
        //Print Error if neccessary
        printf("ERROR: Handle was not attached. Reason: %s not available.n", portName);
    }
    else
    {
        printf("ERROR!!!");
    }
}
else
{
    //If connected we try to set the comm parameters
    DCB dcbSerialParams = { 0 };
    //Try to get the current
    if (!GetCommState(this->hSerial, &dcbSerialParams))
    {
        //If impossible, show an error
        printf("failed to get current serial parameters!");
    }
    else
    {
        //Define serial connection parameters for the arduino board
        dcbSerialParams.BaudRate = CBR_9600;
        dcbSerialParams.ByteSize = 8;
        dcbSerialParams.StopBits = ONESTOPBIT;
        dcbSerialParams.Parity = NOPARITY;
        //Set the parameters and check for their proper application
        if (!SetCommState(hSerial, &dcbSerialParams))
        {
            printf("ALERT: Could not set Serial Port parameters");
        }
        else
        {
            //If everything went fine we're connected
            this->connected = true;
            //We wait 2s as the arduino board will be reseting
            Sleep(ARDUINO_WAIT_TIME);
        }
    }
}
}
Serial::~Serial()
{
//Check if we are connected before trying to disconnect
if (this->connected)
{
    //We're no longer connected
    this->connected = false;
    //Close the serial handler
    CloseHandle(this->hSerial);
}
}
int Serial::ReadData(char *buffer, unsigned int nbChar)
{
//Number of bytes we'll have read
DWORD bytesRead;
//Number of bytes we'll really ask to read
unsigned int toRead;
//Use the ClearCommError function to get status info on the Serial port
ClearCommError(this->hSerial, &this->errors, &this->status);
//Check if there is something to read
if (this->status.cbInQue>0)
{
    //If there is we check if there is enough data to read the required    number
    //of characters, if not we'll read only the available characters to prevent
    //locking of the application.
    if (this->status.cbInQue>nbChar)
    {
        toRead = nbChar;
    }
    else
    {
        toRead = this->status.cbInQue;
    }
    //Try to read the require number of chars, and return the number of read bytes on success
    if (ReadFile(this->hSerial, buffer, toRead, &bytesRead, NULL) && bytesRead != 0)
    {
        return bytesRead;
    }
}
//If nothing has been read, or that an error was detected return -1
return -1;
}

bool Serial::WriteData(char *buffer, unsigned int nbChar)
{
DWORD bytesSend;
//Try to write the buffer on the Serial port
if (!WriteFile(this->hSerial, (void *)buffer, nbChar, &bytesSend, 0))
{
    //In case it don't work get comm error and return false
    ClearCommError(this->hSerial, &this->errors, &this->status);
    return false;
}
else
    return true;
}
bool Serial::IsConnected()
{
//Simply return the connection status
return this->connected;
}

void readme()
{
Serial serial("COM3");
char c[LEN + 1];
int numBytes = 0;
while (true)
{
    numBytes = serial.ReadData(c, LEN);
    if (numBytes != -1)
    {
        // Terminate the string if we want to use c variable as a string
        c[numBytes] = 0;
        break;
    }
}
}
bool Serial::OpenPtoArd()
{
Serial* SP = new Serial("\\.\COM3");    // adjust as needed
if (SP->IsConnected())
{
    bool status = true;
}
}
void Serial::SendtoArd(int val, int var)
{
if (SP->IsConnected())
{
    bool writeData = false;
    writeData = SP->WriteData("test",4);
}
}