基于 Arduino 串行输出的 VB.NET If 语句

Question

我正在构建一个 VB.NET Win Forms 应用程序，该应用程序正在读取 Arduino 的串行输出，我希望 VB.Net 应用程序根据它从 Arduino 读取的内容来做一些事情。我遇到的问题是，即使我可以从 Arduino 读取数据，我似乎也无法将其写入 if 语句。

Arduino 是一个简单的 3 按钮原理图。连接到数字引脚 2、3 和 4 的红色、黄色和绿色按钮。当按下一个按钮时，Arduino 输出文本“红色按钮打开”、“黄色按钮打开”或“绿色按钮打开”，具体取决于哪个按钮按钮被按下。

在 VB.Net 应用程序中，我有一个名为 lblHintRequest 的标签。我可以将 arduino 串行输出加载到这个标签上。但是，一旦我将 arduino 串行输出加载到这个标签上，我似乎无法用它做任何事情。我需要的是一个 if 语句，它将读取按下哪个按钮，然后根据按下的按钮执行某些操作。我还尝试添加一个每 500 毫秒计时的计时器，它会读取标签，但这仍然不起作用。 vb.net 应用程序只是不断跳过 if 语句。

我能想到的最后一件事是使用文本框而不是标签，也许这会有所帮助？但我真的希望这是一个标签。

VB.NET 代码

Imports System.IO.Ports
Public Class frmRoom

Private Sub frmRoom_Load(sender As Object, e As EventArgs) Handles MyBase.Load
 SerialPort1.Open()
End Sub

 Private Sub SerialPort1_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

    'Searching for data input
    Dim ReadCode As String
    ReadCode = SerialPort1.ReadLine

    'Print the button press
    lblHintRequest.Invoke(New MethodInvoker(Sub() lblHintRequest.Text = ReadCode), Nothing)


'This code will not run even though when I invoke the lblhintrequest it shows re button on
    If lblHintRequest.Text = "Red Button On" Then 
        lblHintRequest.ForeColor = Color.Red
    End If

'This if statement does not work either
    If lblHintRequest.Invoke(New MethodInvoker(Sub() lblHintRequest.Text = ReadCode), Nothing) = "Red Button On" Then
        MsgBox("hit")
    End If


End Sub


'----------Code below added for solution response on stack overflow ---
  
Private Sub UpdateHintRequest(code As String)

    If lblHintRequest.InvokeRequired Then
        lblHintRequest.Invoke(Sub() UpdateHintRequest(code))

--Getting stuff to run here was the solution.

 If lblHintRequest.Text = "Red Button On" Then
            lblHintRequest.ForeColor = Color.Red
        End If
    Else

       
    End If


End Sub
End Class

Arduino 代码

const int RedButton = 2;
const int YellowButton = 3;
const int GreenButton = 4;
const int ledpin = 13;

int buttonstateRed =0;
int buttonstateYellow =0;
int buttonstateGreen =0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
pinMode(ledpin,OUTPUT);
pinMode(RedButton, INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
buttonstateRed = digitalRead(RedButton);
if (buttonstateRed == HIGH){
  digitalWrite(ledpin, HIGH);
  Serial.println("Red Button On");
}

buttonstateYellow = digitalRead(YellowButton);
if (buttonstateYellow == HIGH){
  digitalWrite(ledpin, HIGH);
  Serial.println("Yellow Button On");
}


buttonstateGreen = digitalRead(GreenButton);
if (buttonstateGreen == HIGH){
  digitalWrite(ledpin, HIGH);
  Serial.println("Green Button On");
}

if (buttonstateRed == LOW && buttonstateYellow == LOW && buttonstateGreen == LOW){
  digitalWrite(ledpin, LOW);
  //Serial.println("No Button Pressed");
}

Serial.flush();
delay(500);

//Serial.println("Hello");
//delay(250);
}

Answer 1

由于您在变量中有 Arduino 返回的值，因此您可以在 If 语句中使用它：

If ReadCode = "Red Button On" Then 
    lblHintRequest.ForeColor = Color.Red
End If

否则，为了处理您的代码是从不同线程调用的事实（SerialPort 的DataReceived 事件），您可以将整个逻辑包装在自己的Sub 中：

Private Sub UpdateHintRequest(code As String)

    If lblHintRequest.InvokeRequired Then
        lblHintRequest.Invoke(Sub() UpdateHintRequest(code))
    Else

        ' Print the button press
        lblHintRequest.Text = code

        If lblHintRequest.Text = "Red Button On" Then
            lblHintRequest.ForeColor = Color.Red
        End If

        If lblHintRequest.Text = "Red Button On" Then
            MsgBox("hit")
        End If

    End If

End Sub

回到你原来的代码：

Private Sub SerialPort1_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived

    'Searching for data input
    Dim ReadCode As String
    ReadCode = SerialPort1.ReadLine

    UpdateHintRequest(ReadCode)

End Sub