我的 Arduino 正在发送一个信号，但没有发送另一个信号。似乎与代码有关

Question

我的 android 工作室代码是：

bluetooth_connect_btn.setOnClickListener(new View.OnClickListener() {
       @Override
        public void onClick(View v){

           if(BTinit())
           {
               BTconnect();
               beginListenForData();


               // The code below sends the number 3 to the Arduino asking it to send the current state of the door lock so the lock state icon can be updated accordingly
               command = "3";

               try
               {
                   outputStream.write(command.getBytes());
               }
               catch (IOException e)
               {
                   e.printStackTrace();
               }

           }
       }
    });

    lock_state_btn.setOnClickListener(new View.OnClickListener() {
       @Override
        public void onClick(View v){

        if(connected == false)
        {
            Toast.makeText(getApplicationContext(), "Please establish a connection with the bluetooth servo door lock first", Toast.LENGTH_SHORT).show();
        }
        else
        {
            command = "1";

            try
            {
                outputStream.write(command.getBytes()); // Sends the number 1 to the Arduino. For a detailed look at how the resulting command is handled, please see the Arduino Source Code
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
        }

       }
    });
}

void beginListenForData() // begins listening for any incoming data from the Arduino
{
    final Handler handler = new Handler();
    stopThread = false;
    buffer = new byte[1024];

    Thread thread = new Thread(new Runnable()
    {
        public void run()
        {
            while(!Thread.currentThread().isInterrupted() && !stopThread)
            {
                try
                {
                    int byteCount = inputStream.available();

                    if(byteCount > 0)
                    {
                        byte[] rawBytes = new byte[byteCount];
                        inputStream.read(rawBytes);
                        final String string = new String(rawBytes, "UTF-8");

                        handler.post(new Runnable()
                        {
                           public void run()
                           {
                                if(string.equals("3"))
                                {
                                    lock_state_text.setText("Lock State: LOCKED"); // Changes the lock state text
                                    lock_state_img.setImageResource(R.drawable.locked_icon); //Changes the lock state icon
                                }
                                else if(string.equals("4"))
                                {
                                    lock_state_text.setText("Lock State: UNLOCKED");
                                    lock_state_img.setImageResource(R.drawable.unlocked_icon);
                                }
                           }
                        });
                    }
                }
                catch (IOException ex)
                {
                    stopThread = true;
                }
            }
        }
    });

    thread.start();
}

我的 Arduino 代码是：

#include <Servo.h>
#include <EEPROM.h>

Servo servo;
char state;

void setup() {
EEPROM.write(0,2);
  // put your setup code here, to run once:
  servo.attach(7);

  if(EEPROM.read(0) == 1) // Reads the EEPROM value stored to know what state the door lock was in before it was last turned off
  {                       // An EEPROM value of 1 means UNLOCKED and a value of 2 means LOCKED
    servo.write(0); // Rotates the servo to the unlocked position
    delay(200);
  }
  else if(EEPROM.read(0) == 2)
  {
    servo.write(75); // Rotates the servo to the locked position
    delay(200);
  }

  Serial.begin(9600);
}

void loop() {
EEPROM.write(0,2);
  // put your main code here, to run repeatedly:
  if(Serial.available() > 0)
  {
    char data;
    data = Serial.read(); // The variable data is used to store the value sent by the Android app

switch(data)
{
  case '1': 
    if(EEPROM.read(0) == 1) //An EEPROM value of 1 means it is currently unlocked
    {
      EEPROM.write(0, 2); // Writes the number 2 to address 0 on the Arduino's EEPROM. This value will be used by the Arduino to remember the last state the door lock was in
      Serial.print("3"); // Sends the number 3 to the Android app. To see what this does, please see the Android Studio Project file


        servo.write(75);
        delay(15);

    }
    else if(EEPROM.read(0) == 2) //An EEPROM value of 2 means it i currently locked
    {
      EEPROM.write(0, 1); // Writes the number 1 to address 0 on the Arduino's EEPROM. This value will be used by the Arduino to remember the last state the door lock was in
      Serial.print("4"); // Sends the number 4 to the Android app. The number sent will be used by the app to update the locked/unlocked icon

        servo.write(0);
        delay(15);
    }
    break;
  case '3':
      if(EEPROM.read(0) == '1')
      {
        Serial.print("4");
        }

      else if(EEPROM.read(0) == '2')
      {
        Serial.print("3");
        }   
        break;
    }
  }

 }

我已经制作了 apk 文件并在 arduino uno 上上传了 arduino 代码（因此这两个代码都没有错误）。现在，当我点击连接时，它会建立连接，然后当我点击 lock_state_btn 时，arduino 会向伺服电机发送信号以改变其位置，同时还会发回信号来改变图标。但是当我点击lock_state_btn 再次，它应该再次改变它没有做的位置。有人可以帮我吗？

Answer 1

在 switch 中测试时，您的 EEPROM 变量始终包含 2。 考虑一下我从您的 Arduino 程序中取出的这段代码：

void loop() {
 // EEPROM (0) value could be 1 or 2
 EEPROM.write(0,2); // <—
 // EEPROM value is 2
 switch(data)
 {
     case '1': 
     if(EEPROM.read(0) == 1) // newer executed
     {
        EEPROM.write(0, 2);
     }
     else if(EEPROM.read(0) == 2) // always executed, independently from actual servo position
     {
        EEPROM.write(0, 1);
         // EEPROM value is 1, but will be overwritten at the beginning of he next loop execution
         // (i.e. before any new call to this switch statement)
     }
     break;
 }

您只需删除标有 // <— 的行即可使您的程序运行。