串口绘图

Question

我有一个arduino nano，它的行为就像电压表 它读取ADC（模拟端口A0）然后将数据从串口发送到计算机，我设计了一个可视化的基本程序来读取这些数据并将其绘制在图表中。 但不知何故，vb中的计时器和arduino中的延迟有时不会同步并返回false值。我能做什么 ？ False Value's picture

VB侧码：

  Private Sub connect_BTN_Click(sender As Object, e As EventArgs) Handles connect_BTN.Click
        Try
            If (connect_BTN.Text = "Connect") Then
                If (comPORT <> "") Then

                    SerialPort1.Close()
                    SerialPort1.PortName = comPORT
                    SerialPort1.BaudRate = 9600
                    SerialPort1.DataBits = 8
                    SerialPort1.Parity = Parity.None
                    SerialPort1.StopBits = StopBits.One
                    SerialPort1.Handshake = Handshake.None
                    SerialPort1.Encoding = System.Text.Encoding.Default 'very important!
                    SerialPort1.ReadTimeout = 10000

                    SerialPort1.Open()
                    connect_BTN.Text = "Dis-connect"
                    'Timer1.Enabled = True
                    'Timer_LBL.Text = "Timer: ON"
                    STATUS.BackColor = System.Drawing.Color.LightGreen
                Else
                    MsgBox("Select a COM port first")
                End If
            Else
                SerialPort1.Close()
                connect_BTN.Text = "Connect"
                Timer1.Enabled = False
                Timer_LBL.Text = "Timer: OFF"
                STATUS.BackColor = System.Drawing.Color.Red
            End If
        Catch exx As Exception
            MsgBox(exx.Message)
        End Try
    End Sub
      Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        receivedData = ReceiveSerialData()
        RichTextBox1.Text += receivedData & vbCrLf
        Dim meghdar As Integer = Convert.ToInt32(receivedData)
        s.Points.AddY(meghdar)
    End Sub
    Function ReceiveSerialData() As String
        Try
            Dim Incoming As String
            Try
                Incoming = SerialPort1.ReadExisting()
                If Incoming Is Nothing Then
                    Return 0
                Else
                    Return Convert.ToInt32(Incoming)
                End If
            Catch ex As TimeoutException
                Return "Error: Serial Port read timed out."
            End Try
        Catch ex As Exception
        End Try
Arduino Code :

    /*
  SD card datalogger

 The circuit:
 * analog sensors on analog ins 0, 1, and 2
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 4 (for MKRZero SD: SDCARD_SS_PIN)
*/

#include <SPI.h>
#include <SD.h>

const int chipSelect = 4;

void setup() {
  // Open serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }


  //Serial.print("Initializing SD card...");

  // see if the card is present and can be init-ialized:
  if (!SD.begin(chipSelect)) {
    //Serial.println("Card failed, or not present");
    // don't do anything more:
    return;
  }
 // Serial.println("card initialized.");
   File dataFile = SD.open("datalog.txt", FILE_WRITE);
   if (dataFile) {
    dataFile.println("ConePenetroMeter TEST results :");
    dataFile.close();
    // print to the serial port too:
    //Serial.println("ConePenetroMeter TEST results :");

  }
}

void loop() {
  // make a string for assembling the data to log:
  String dataString = "";

  // read three sensors and append to the string:

    int sensor = analogRead(A0);
    dataString += String(sensor);

  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  File dataFile = SD.open("datalog.txt", FILE_WRITE);

  // if the file is available, write to it:
  if (dataFile) {

    dataFile.println(dataString);
    dataFile.close();
    // print to the serial port too:
    Serial.println(sensor);

  }
  // if the file isn't open, pop up an error:
  else {
    //Serial.println("error opening datalog.txt");
  }
  delay(300);
}

arduino的延迟是300毫秒，vb.net中的定时器间隔也是300毫秒