「BLEモジュールのスキャンプログラム作成」で作成したスキャンプログラムに、writeとnotifyの機能を追加し、ペリフェラルとして作成したXIAO ESP32C3と通信します。
- Android携帯：SH-52E Android14(API34) bleバージョン5.3
- BLEモジュール：XIAO ESP32C3 bleバージョン5.0
- Android開発環境：Android Studio Otter 2 Feature Drop | 2025.2.2
BLEモジュールの通信プログラムの作成
ペリフェラルとして作成したXIAO ESP32C3との接続およびデータ通信のために、次のような通信プログラムを作成します。
Manifest.xmlは、「BLEモジュールのスキャンプログラム作成」で作成したコードとなります。
- Notify を有効にするために、mGatt.setCharacteristicNotification と CCCD（0x2902）へ書き込みます。
- BLE GATT 操作は非同期のため、 onCharacteristicWrite / onCharacteristicChanged や Descriptor 書き込みのコールバックを使用します。
- Android 12+ では、 BLUETOOTH_CONNECT の権限がないと、 connectGatt/characteristic 操作が SecurityException を投げることがあるため、実行前にチェックします。
BleEsp32\app\src\main\java\com\tomosoft\BleEsp32\MainActivity.java
package com.tomosoft.BleEsp32;
import android.os.Bundle;
import androidx.activity.EdgeToEdge;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;
import androidx.core.app.ActivityCompat;
import android.Manifest;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothGatt;
import android.bluetooth.BluetoothGattCallback;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattDescriptor;
import android.bluetooth.BluetoothGattService;
import android.bluetooth.BluetoothManager;
import android.bluetooth.le.BluetoothLeScanner;
import android.bluetooth.le.ScanCallback;
import android.bluetooth.le.ScanResult;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Build;
import android.text.TextUtils;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.annotation.NonNull;
import androidx.core.content.ContextCompat;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private BluetoothAdapter bluetoothAdapter;
private BluetoothLeScanner bleScanner;
private final List<String> devices = new ArrayList<>();
private final List<BluetoothDevice> deviceObjs = new ArrayList<>();
private ArrayAdapter<String> adapter;
private BluetoothGatt mGatt;
private BluetoothGattCharacteristic targetChar;
private boolean notifyEnabled = false;
private TextView tvStatus;
private TextView tvLog;
private EditText etServiceUuid, etCharUuid, etWriteValue;
private Button btnWrite, btnToggleNotify;
private static final UUID CCCD_UUID = UUID.fromString("00002902-0000-1000-8000-00805f9b34fb");
// Bluetooth 有効化用
private ActivityResultLauncher<Intent> enableBtLauncher;
//// ////////////
private ActivityResultLauncher<Intent> enableBtIntent;
private final ScanCallback scanCallback = new ScanCallback() {
@Override
public void onScanResult(int callbackType, ScanResult result) {
runOnUiThread(() -> {
String addr = result.getDevice().getAddress();
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
String name = result.getDevice().getName();
String line = addr + " / " + (name != null ? name : "N/A") + " / RSSI:" + result.getRssi();
if (!devices.contains(line)) {
devices.add(0, line);
deviceObjs.add(0, result.getDevice());
adapter.notifyDataSetChanged();
}
});
}
};
private final String[] REQUIRED_PERMISSIONS_API31 = new String[]{
Manifest.permission.BLUETOOTH_SCAN,
Manifest.permission.BLUETOOTH_CONNECT
};
private final ActivityResultLauncher<String[]> requestPermissionLauncher =
registerForActivityResult(new ActivityResultContracts.RequestMultiplePermissions(), result -> {
boolean granted = true;
for (Boolean b : result.values()) {
if (b == null || !b) { granted = false; break; }
}
if (granted) {
startBleScan();
} else {
tvStatus.setText("Permissions denied");
}
});
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
EdgeToEdge.enable(this);
setContentView(R.layout.activity_main);
ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.root), (v, insets) -> {
Insets systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars());
v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom);
return insets;
});
///////////////////
Button btnStart = findViewById(R.id.btnStart);
Button btnStop = findViewById(R.id.btnStop);
tvStatus = findViewById(R.id.tvStatus);
tvLog = findViewById(R.id.tvLog);
ListView listView = findViewById(R.id.listView);
etServiceUuid = findViewById(R.id.etServiceUuid);
etCharUuid = findViewById(R.id.etCharUuid);
etWriteValue = findViewById(R.id.etWriteValue);
btnWrite = findViewById(R.id.btnWrite);
btnToggleNotify = findViewById(R.id.btnToggleNotify);
adapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, devices);
listView.setAdapter(adapter);
BluetoothManager manager = (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE);
bluetoothAdapter = manager.getAdapter();
enableBtLauncher = registerForActivityResult(
new ActivityResultContracts.StartActivityForResult(),
result -> {
if (result.getResultCode() == Activity.RESULT_OK) {
appendLog("Bluetooth enabled");
prepareAndStartScan();
} else {
appendLog("Bluetooth not enabled");
}
});
btnStart.setOnClickListener(v -> prepareAndStartScan());
btnStop.setOnClickListener(v -> stopBleScan());
listView.setOnItemClickListener((parent, view, position, id) -> {
BluetoothDevice device = deviceObjs.get(position);
appendLog("Selected device: " + device.getAddress());
connectToDevice(device);
});
btnWrite.setOnClickListener(v -> {
if (targetChar == null) {
appendLog("No characteristic selected");
return;
}
String input = etWriteValue.getText().toString();
if (TextUtils.isEmpty(input)) {
appendLog("Write value empty");
return;
}
byte[] data = parseInputToBytes(input);
writeCharacteristic(data);
});
btnToggleNotify.setOnClickListener(v -> {
if (targetChar == null) {
appendLog("No characteristic selected");
return;
}
setNotify(!notifyEnabled);
});
}
private void prepareAndStartScan() {
if (bluetoothAdapter == null) {
tvStatus.setText("Bluetooth not supported");
return;
}
if (!bluetoothAdapter.isEnabled()) {
// リクエストして Bluetooth を有効化
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
this.enableBtIntent.launch(enableBtIntent);
return;
}
// Android 12+ の権限チェック
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
boolean scanGranted = ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) == PackageManager.PERMISSION_GRANTED;
boolean connectGranted = ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED;
if (!scanGranted || !connectGranted) {
requestPermissionLauncher.launch(REQUIRED_PERMISSIONS_API31);
return;
}
} else {
// Android 6〜11 の場合は LOCATION 権限が必要なことがある（スキャンで位置情報を推測できるため）
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 1001);
return;
}
}
startBleScan();
}
private void startBleScan() {
if (bluetoothAdapter == null || !bluetoothAdapter.isEnabled()) {
tvStatus.setText("Bluetooth disabled");
return;
}
// BluetoothLeScanner の取得（CONNECT 権限が必要な操作もある）
bleScanner = bluetoothAdapter.getBluetoothLeScanner();
if (bleScanner == null) {
tvStatus.setText("BLE scanner not available");
return;
}
devices.clear();
deviceObjs.clear();
adapter.notifyDataSetChanged();
// 権限チェック（安全のため）
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&
ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_SCAN) != PackageManager.PERMISSION_GRANTED) {
tvStatus.setText("BLUETOOTH_SCAN missing");
return;
}
bleScanner.startScan(scanCallback);
tvStatus.setText("Scanning...");
appendLog("Scan started");
}
private void stopBleScan() {
if (bleScanner != null) {
// 権限チェック
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&
ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
tvStatus.setText("BLUETOOTH_CONNECT missing");
return;
}
try {
bleScanner.stopScan(scanCallback);
appendLog("Scan stopped");
} catch (Exception e) {
// まれに例外が出ることがあるのでキャッチ
e.printStackTrace();
}
tvStatus.setText("Stopped");
}
}
private void connectToDevice(@NonNull BluetoothDevice device) {
// Permission check for connectGatt
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&
ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
appendLog("BLUETOOTH_CONNECT permission missing. Cannot connect.");
return;
}
appendLog("Connecting to " + device.getAddress());
// 古い API を使う単純な実装
if (mGatt != null) {
mGatt.close();
mGatt = null;
}
mGatt = device.connectGatt(this, false, gattCallback);
tvStatus.setText("Connecting...");
}
private final BluetoothGattCallback gattCallback = new BluetoothGattCallback() {
@Override
public void onConnectionStateChange(@NonNull BluetoothGatt gatt, int status, int newState) {
super.onConnectionStateChange(gatt, status, newState);
if (status != BluetoothGatt.GATT_SUCCESS) {
appendLog("Connection state change error: " + status);
}
if (newState == android.bluetooth.BluetoothProfile.STATE_CONNECTED) {
appendLog("Connected, discovering services...");
runOnUiThread(() -> tvStatus.setText("Connected"));
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
boolean ok = gatt.discoverServices();
appendLog("discoverServices called: " + ok);
} else if (newState == android.bluetooth.BluetoothProfile.STATE_DISCONNECTED) {
appendLog("Disconnected");
runOnUiThread(() -> {
tvStatus.setText("Disconnected");
targetChar = null;
notifyEnabled = false;
btnToggleNotify.setText("Enable Notify");
});
}
}
@Override
public void onServicesDiscovered(@NonNull BluetoothGatt gatt, int status) {
super.onServicesDiscovered(gatt, status);
appendLog("Services discovered: status=" + status);
// サービス/キャラ探索ロジック
BluetoothGattService service = null;
BluetoothGattCharacteristic chr = null;
String svcInput = etServiceUuid.getText().toString().trim();
String chrInput = etCharUuid.getText().toString().trim();
if (!svcInput.isEmpty()) {
try {
UUID svcUuid = UUID.fromString(svcInput);
service = gatt.getService(svcUuid);
} catch (IllegalArgumentException e) {
appendLog("Invalid service UUID format");
}
}
if (service != null && !chrInput.isEmpty()) {
try {
UUID chrUuid = UUID.fromString(chrInput);
chr = service.getCharacteristic(chrUuid);
} catch (IllegalArgumentException e) {
appendLog("Invalid characteristic UUID format");
}
}
// 指定がない場合は探索して最初の書き込み可能 or notify 可能なキャラクタリスティックを選ぶ
if (chr == null) {
// try all services
for (BluetoothGattService s : gatt.getServices()) {
for (BluetoothGattCharacteristic c : s.getCharacteristics()) {
final int props = c.getProperties();
if ((props & BluetoothGattCharacteristic.PROPERTY_WRITE) != 0
|| (props & BluetoothGattCharacteristic.PROPERTY_WRITE_NO_RESPONSE) != 0
|| (props & BluetoothGattCharacteristic.PROPERTY_NOTIFY) != 0
|| (props & BluetoothGattCharacteristic.PROPERTY_INDICATE) != 0) {
chr = c;
service = s;
break;
}
}
if (chr != null) break;
}
}
if (chr != null) {
targetChar = chr;
appendLog("Selected characteristic: " + chr.getUuid());
runOnUiThread(() -> {
tvStatus.setText("Service/Char ready");
});
} else {
appendLog("No suitable characteristic found");
}
}
@Override
public void onCharacteristicWrite(@NonNull BluetoothGatt gatt, @NonNull BluetoothGattCharacteristic characteristic, int status) {
super.onCharacteristicWrite(gatt, characteristic, status);
appendLog("Characteristic write callback: status=" + status + " uuid=" + characteristic.getUuid());
}
@Override
public void onCharacteristicChanged(@NonNull BluetoothGatt gatt, @NonNull BluetoothGattCharacteristic characteristic) {
super.onCharacteristicChanged(gatt, characteristic);
byte[] val = characteristic.getValue();
//appendLog("Notification from " + characteristic.getUuid() + " : " + bytesToHexOrText(val));
appendLog("Notification from " + characteristic.getUuid() + " : " + new String(val, StandardCharsets.US_ASCII));
}
};
private void writeCharacteristic(byte[] data) {
if (mGatt == null || targetChar == null) {
appendLog("Not connected or no characteristic");
return;
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&
ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
appendLog("BLUETOOTH_CONNECT missing for write");
return;
}
targetChar.setValue(data);
boolean success = mGatt.writeCharacteristic(targetChar);
appendLog("writeCharacteristic called: " + success);
}
private void setNotify(boolean enable) {
if (mGatt == null || targetChar == null) {
appendLog("Not connected or no characteristic");
return;
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S &&
ContextCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
appendLog("BLUETOOTH_CONNECT missing for notify");
return;
}
boolean localSet = mGatt.setCharacteristicNotification(targetChar, enable);
appendLog("setCharacteristicNotification(local) returned: " + localSet);
// Descriptor を書き込む必要あり (0x2902)
BluetoothGattDescriptor descriptor = targetChar.getDescriptor(CCCD_UUID);
if (descriptor != null) {
descriptor.setValue(enable ? BluetoothGattDescriptor.ENABLE_NOTIFICATION_VALUE : BluetoothGattDescriptor.DISABLE_NOTIFICATION_VALUE);
boolean wrote = mGatt.writeDescriptor(descriptor);
appendLog("writeDescriptor called: " + wrote);
} else {
appendLog("CCCD descriptor not found on characteristic");
}
notifyEnabled = enable;
runOnUiThread(() -> btnToggleNotify.setText(enable ? "Disable Notify" : "Enable Notify"));
}
private byte[] parseInputToBytes(String in) {
in = in.trim();
// hex-like: contains spaces or hex digits and no letters beyond A-F and spaces
if (in.matches("(?i)^[0-9a-f ]+$")) {
String[] parts = in.split("\\s+");
byte[] out = new byte[parts.length];
for (int i = 0; i < parts.length; i++) {
out[i] = (byte) Integer.parseInt(parts[i], 16);
}
return out;
} else {
return in.getBytes(StandardCharsets.UTF_8);
}
}
private String bytesToHexOrText(byte[] b) {
if (b == null || b.length == 0) return "<empty>";
// try to display both
StringBuilder hex = new StringBuilder();
boolean ascii = true;
for (byte by : b) {
hex.append(String.format("%02X ", by));
if (by < 0x20 || by > 0x7E) ascii = false;
}
String txt = ascii ? new String(b, StandardCharsets.UTF_8) : "<non-ascii>";
return hex.toString().trim() + " / " + txt;
}
private void appendLog(final String line) {
runOnUiThread(() -> {
tvLog.append(line + "\n");
});
}
@Override
protected void onPause() {
super.onPause();
stopBleScan();
if (mGatt != null) {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return;
}
mGatt.close();
mGatt = null;
}
}
}
次の画面レイアウトを使用します。
BLEモジュールの通信プログラムの実行
作成した通信プログラムを携帯にダウンロードして実行すると、次のような内容が画面に表示されます。
Android携帯画面の「Write」ボタンを押すと、XIAO ESP32C3のシリアルモニタには次のメッセージが表示されます。
