ESP32側
/*
Video: https://www.youtube.com/watch?v=oCMOYS71NIU
Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
Ported to Arduino ESP32 by Evandro Copercini
Create a BLE server that, once we receive a connection, will send periodic notifications.
The service advertises itself as: 6E400001-B5A3-F393-E0A9-E50E24DCCA9E
Has a characteristic of: 6E400002-B5A3-F393-E0A9-E50E24DCCA9E – used for receiving data with “WRITE”
Has a characteristic of: 6E400003-B5A3-F393-E0A9-E50E24DCCA9E – used to send data with “NOTIFY”
The design of creating the BLE server is:
1. Create a BLE Server
2. Create a BLE Service
3. Create a BLE Characteristic on the Service
4. Create a BLE Descriptor on the characteristic
5. Start the service.
6. Start advertising.
In this example rxValue is the data received (only accessible inside that function).
And txValue is the data to be sent, in this example just a byte incremented every second.
*/
#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
BLEServer *pServer = NULL;
BLECharacteristic *pTxCharacteristic;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint8_t txValue = 0;
// See the following for generating UUIDs:
// https://www.uuidgenerator.net/
#define SERVICE_UUID “6E400001-B5A3-F393-E0A9-E50E24DCCA9E” // UART service UUID
#define CHARACTERISTIC_UUID_RX “6E400002-B5A3-F393-E0A9-E50E24DCCA9E”
#define CHARACTERISTIC_UUID_TX “6E400003-B5A3-F393-E0A9-E50E24DCCA9E”
class MyServerCallbacks : public BLEServerCallbacks {
void onConnect(BLEServer *pServer) {
deviceConnected = true;
};
void onDisconnect(BLEServer *pServer) {
deviceConnected = false;
}
};
class MyCallbacks : public BLECharacteristicCallbacks {
void onWrite(BLECharacteristic *pCharacteristic) {
String rxValue = pCharacteristic->getValue();
if (rxValue.length() > 0) {
Serial.println(“*********”);
Serial.print(“Received Value: “);
for (int i = 0; i < rxValue.length(); i++) {
Serial.print(rxValue[i]);
}
Serial.println();
Serial.println(“*********”);
}
}
};
void setup() {
Serial.begin(115200);
// Create the BLE Device
BLEDevice::init(“AQUA-FAN-BLE”);
// Create the BLE Server
pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pTxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX, BLECharacteristic::PROPERTY_NOTIFY);
pTxCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pRxCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX, BLECharacteristic::PROPERTY_WRITE);
pRxCharacteristic->setCallbacks(new MyCallbacks());
// Start the service
pService->start();
// Start advertising
pServer->getAdvertising()->start();
Serial.println(“Waiting a client connection to notify…”);
}
void loop() {
if (deviceConnected) {
pTxCharacteristic->setValue(&txValue, 1);
pTxCharacteristic->notify();
txValue++;
delay(100); // bluetooth stack will go into congestion, if too many packets are sent
}
// disconnecting
if (!deviceConnected && oldDeviceConnected) {
delay(500); // give the bluetooth stack the chance to get things ready
pServer->startAdvertising(); // restart advertising
Serial.println(“start advertising”);
oldDeviceConnected = deviceConnected;
}
// connecting
if (deviceConnected && !oldDeviceConnected) {
// do stuff here on connecting
oldDeviceConnected = deviceConnected;
}
}
flutter側コード
FlutterBluePlus flutterBlue = FlutterBluePlus();//.instance;
BluetoothDevice? connectedDevice;
List<BluetoothService> services = [];
String status = "Scanning...";
@override
void initState() {
super.initState();
startScan();
}
void startScan() {
FlutterBluePlus.startScan(timeout: Duration(seconds: 4));
FlutterBluePlus.scanResults.listen((results) {
for (ScanResult result in results) {
if (result.device.name == "AQUA-FAN-BLE") { // デバイス名を指定
stopScan();
connectToDevice(result.device);
break;
}
}
});
}
void stopScan() {
FlutterBluePlus.stopScan();
}
void connectToDevice(BluetoothDevice device) async {
setState(() {
status = "Connecting...";
});
await device.connect();
setState(() {
connectedDevice = device;
status = "Connected";
});
discoverServices(device);
}
void discoverServices(BluetoothDevice device) async {
try {
List<BluetoothService> services = await device.discoverServices();
setState(() {
this.services = services;
});
for (BluetoothService service in services) {
print("Service UUID: ${service.uuid}");
for (BluetoothCharacteristic characteristic in service.characteristics) {
print("Characteristic UUID: ${characteristic.uuid}");
// TXキャラクタリスティックに対して通知を有効にする
if (characteristic.uuid.toString().toLowerCase() == "6e400003-b5a3-f393-e0a9-e50e24dcca9e") {
await characteristic.setNotifyValue(true);
characteristic.value.listen((value) {
setState(() {
receivedData = String.fromCharCodes(value); // 受信データを文字列に変換
});
print("Notification received: $value");
});
}
}
}
} catch (e) {
print("Error discovering services: $e");
}
}
String receivedData = "";
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('BLE Client'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text("Status: $status"),
if (connectedDevice != null) Text("Connected to: ${connectedDevice!.name}"),
if (services.isNotEmpty) Text("Services discovered: ${services.length}"),
Text("Received Data: $receivedData"),
],
),
),
);
}
void readCharacteristic(BluetoothCharacteristic characteristic) async {
try{
List<int> value = await characteristic.read();
print("Characteristic Value: $value");
}catch(e){
print("Failed to read characteristic: $e");
}
}
