Android如何通过App来控制来呀开发板上Led灯的亮灭

Android通过App来控制开发板上LED灯的亮灭需要使用Android开发板上的GPIO接口。具体步骤如下：

1. 在Android App中添加权限：

在AndroidManifest.xml文件中添加以下权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.WRITE_SETTINGS" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.INSTALL_PACKAGES" />
<uses-permission android:name="android.permission.DELETE_PACKAGES" />
<uses-permission android:name="android.permission.RESTART_PACKAGES" />
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
<uses-permission android:name="android.permission.GET_TASKS" />
<uses-permission android:name="android.permission.SET_WALLPAPER" />
<uses-permission android:name="android.permission.SET_WALLPAPER_HINTS" />
<uses-permission android:name="android.permission.SET_TIME_ZONE" />
<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.READ_CALL_LOG" />
<uses-permission android:name="android.permission.WRITE_CALL_LOG" />
<uses-permission android:name="android.permission.RECORD_VIDEO" />
<uses-permission android:name="android.permission.READ_SMS" />
<uses-permission android:name="android.permission.WRITE_SMS" />
<uses-permission android:name="android.permission.SEND_SMS" />
<uses-permission android:name="android.permission.RECEIVE_SMS" />
<uses-permission android:name="android.permission.RECEIVE_MMS" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_SYNC_SETTINGS" />
<uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS" />
<uses-permission android:name="android.permission.READ_PROFILE" />
<uses-permission android:name="android.permission.WRITE_PROFILE" />
<uses-permission android:name="android.permission.READ_SOCIAL_STREAM" />
<uses-permission android:name="android.permission.READ_USER_DICTIONARY" />
<uses-permission android:name="android.permission.WRITE_USER_DICTIONARY" />
<uses-permission android:name="android.permission.MANAGE_ACCOUNTS" />
<uses-permission android:name="android.permission.READ_PHONE_NUMBERS" />
<uses-permission android:name="android.permission.USE_CREDENTIALS" />
<uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER" />
<uses-permission android:name="android.permission.ACCESS_DOWNLOAD_MANAGER_ADVANCED" />
<uses-permission android:name="android.permission.ACCESS_CACHE_FILESYSTEM" />
<uses-permission android:name="android.permission.ACCESS_ALL_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_MTP" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.MANAGE_DOCUMENTS" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_MEDIA_STORAGE" />
<uses-permission android:name="android.permission.WRITE_MEDIA_STORAGE" />

2. 在App中创建GPIO控制类：

创建一个名为GPIOControl的Java类，用于控制GPIO口的开关。代码如下：

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

public class GPIOControl {

    private static final String GPIO_ROOT_PATH = "/sys/class/gpio/";
    private static final String GPIO_EXPORT_PATH = GPIO_ROOT_PATH + "export";
    private static final String GPIO_UNEXPORT_PATH = GPIO_ROOT_PATH + "unexport";

    private String mGpioPath;

    public GPIOControl(int gpio_num) {
        mGpioPath = GPIO_ROOT_PATH + "gpio" + gpio_num + "/";
    }

    public boolean open() {
        File gpioFile = new File(GPIO_EXPORT_PATH);
        if (!gpioFile.exists()) {
            return false;
        }

        try {
            FileWriter exportFile = new FileWriter(gpioFile);
            exportFile.write(Integer.toString(getGpioNum(mGpioPath)));
            exportFile.flush();
            exportFile.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

    public boolean close() {
        File gpioFile = new File(GPIO_UNEXPORT_PATH);
        if (!gpioFile.exists()) {
            return false;
        }

        try {
            FileWriter unexportFile = new FileWriter(gpioFile);
            unexportFile.write(Integer.toString(getGpioNum(mGpioPath)));
            unexportFile.flush();
            unexportFile.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

    public boolean setDirection(String direction) {
        File directionFile = new File(mGpioPath + "direction");
        if (!directionFile.exists()) {
            return false;
        }

        try {
            FileWriter directionWriter = new FileWriter(directionFile);
            directionWriter.write(direction);
            directionWriter.flush();
            directionWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

    public boolean setValue(int value) {
        File valueFile = new File(mGpioPath + "value");
        if (!valueFile.exists()) {
            return false;
        }

        try {
            FileWriter valueWriter = new FileWriter(valueFile);
            valueWriter.write(Integer.toString(value));
            valueWriter.flush();
            valueWriter.close();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }

        return true;
    }

    private int getGpioNum(String gpio_path) {
        int start = gpio_path.indexOf("gpio");
        int end = gpio_path.indexOf("/", start);
        String gpio_num_str = gpio_path.substring(start + 4, end);
        return Integer.parseInt(gpio_num_str);
    }
}

3. 在App中调用控制类：

在App的主Activity中调用GPIOControl类，控制LED灯的亮灭。代码如下：

public class MainActivity extends AppCompatActivity {

    GPIOControl gpioControl;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gpioControl = new GPIOControl(23);
        gpioControl.open();
        gpioControl.setDirection("out");
    }

    @Override
    protected void onDestroy() {
        gpioControl.close();
        super.onDestroy();
    }

    public void turnOn(View view) {
        gpioControl.setValue(1);
    }

    public void turnOff(View view) {
        gpioControl.setValue(0);
    }
}

在App的布局文件中添加两个按钮，分别用于控制LED灯的开和关：

<LinearLayout
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:gravity="center">

    <Button
        android:id="@+id/button_turn_on"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Turn On"
        android:onClick="turnOn"/>

    <Button
        android:id="@+id/button_turn_off"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Turn Off"
        android:onClick="turnOff"/>
</LinearLayout>

以上就是使用Android App控制开发板上LED灯的亮灭的具体步骤。