Develop Reference

How do I send/receive data using bluetooth in flutter?

I'm trying to receive and send data from and to an arduino uno. I've tried looking into flutter blue plugin and flutter bluetooth serial plugin ,flutter serial plugin
seems to be incomplete and flutter blue lacks examples or documentation, and the official github example is way too complicated and is irrelevant to what i want to do. I want a very simple method of sending or retrieving data from an arduino using a HC-05 module.

If you are working with a HC-05 module (No Low Energy Bluetooth). Use ´flutter_bluetooth_serial´ package. It is not a great package, but it should work.
This example may not work.
Scan for devices:
//Here the scan results will be saved
List<BluetoothDiscoveryResult> results = List<BluetoothDiscoveryResult>();
void startDiscovery() {
streamSubscription = FlutterBluetoothSerial.instance.startDiscovery().listen((r) {
results.add(r);
});
streamSubscription.onDone(() {
//Do something when the discovery process ends
});
}
Connect to device:
Use this function when you select a device from the result list.
BluetoothConnection connection;
connect(String address) async {
try {
connection = await BluetoothConnection.toAddress(address);
print('Connected to the device');
connection.input.listen((Uint8List data) {
//Data entry point
print(ascii.decode(data));
})
} catch (exception) {
print('Cannot connect, exception occured');
}
}
Send data:
Future send(Uint8List data) async {
connection.output.add(data);
await _connection.output.allSent;
}

Try the example app from the ´flutter_bluetooth_serial´-package now. They even included reading data from an HC-05-module! If you want something simpler, try extracting the essential code from the example and copycoding it into another app.

How to determine network strength using cordova plugin or Ionic v1

I am developing Hybrid mobile app using Ionic to support both iOS and Android. Just wanted to determine network strength like Poor connection. Using cordova-plugin-network-information
I am able to find network connection type like WiFi, 2G,3G etc. But not sure how to determine connection speed to ensure whether it has poor connection.
Can anyone please help me to get this?
Thank you in Advance.

I was having the same problem days ago. While I could not find best solution. I have created a new cordova plugin that you can use to get most of the basic network informations you need.
All you have to do is to run this command
cordova plugin add cordova-plugin-network-signal-strength
Usage
The API has only one method window["networkSignalStrength"].networkInfo(infoType, callback).
infoType parameter could either be:
null : to get all the network details including signal strength, network type and connection state
CONNECTION_STATE : to get only the connection state which will return 0 or 1.
0 : disconnected
1 : connected
SIGNAL_STRENGTH : to get only the signal strength information.
This return an object which include rssi, rssq, rssnr, rsrp, signal level and lte level
signal type range:
RSSI: [-113, -51, "dBm"]
RSSNR: [-20, +30, "dB"]
RSRQ: [-34, 3, "dB"]
RSRP: [-140, -43, "dBm"]
NETWORK_TYPE : to get type of connected network. Return integer -1 to 5
-1 : unknown
0 : disconnected
1 : wifi
2 : 2g
3 : 3g
4 : 4g
5 : roaming
code snippet
// to get full network information
window['networkSignalStrength'] ? .networkInfo(null, (networkInfoData) => {
console.log('network signal data :', networkInfoData)
});
/**
You receive -1 as a result if the device is unable to get a known network
type and 0 for offline or disconnected state.
*/
// to get only signal strength
window['networkSignalStrength'] ? .networkInfo("SIGNAL_STRENGTH",
(networkInfoData) => {
console.log('network signal data :', networkInfoData)
});
/**
You should call the window.SignalStrength.dbm only after cordova platform is
ready. Example in Ionic framework:
*/
// ensure platform is ready before calling the plugin method
$ionicPlatform.ready().then(() => {
// Platform now ready, execute any required native code
setInterval(() => {
window['networkSignalStrength'] ? .networkInfo(null, (networkInfoData) => {
console.log('network signal data :', networkInfoData)
});
}, 5000)
});
cordova-plugin-network-signal-strength

Can't connect HM10 to Android device

I am currently developing a device that uses a Pro Micro micro-controller, an HM10 ble module (I checked and this isn't a BLE-CC41A), and several Android devices. My issue is the connection between the Android and the HM10. A few days ago the connection between these two worked well and I could send and receive messages between these two. Now the Android can see the HM10 module but for some reason it cannot connect. I have tried several applications such as "nRF Connect", "BLE Scanner", and "MSMBle" all with no results.
All seems fine on the Pro Micro side. With the code I am using I can send AT commands to the HM10. In case you were wondering what code I used for the pro micro:
#include <SoftwareSerial.h>
SoftwareSerial bluetooth(9, 8); //RX|TX
void setup(){
Serial.begin(9600);
bluetooth.begin(9600); // default baud rate
Serial.println("AT commands: ");
}
void loop(){
bluetoothCommunication();
serialCommunication();
}
void serialCommunication() {
if(Serial.available() >0){ //read from the Serial and print to the HM-10
bluetooth.write(Serial.read());
}
}
void bluetoothCommunication(){
String readStr; //expect a string like wer,qwe rty,123 456,hyre kjhg, or like hello world,who are you?,bye!,
while (bluetooth.available() > 0) { //read from the HM-10 and print in the Serial
delay(10); //small delay to allow input buffer to fill
char inChar = bluetooth.read(); //gets one byte from serial buffer
readStr += inChar ; //makes the string readString
}
if (readStr.length() >0) {
Serial.println(readStr); //prints string to serial port out
}
}
About the BLE HM10 module I pretty much use the default settings but changed the name and password. I also want to note that I tested with three HM10 modules and none can connect to an Android device.
Has anyone had the same issue? Did Android make an update that made HM10 modules unusable?

i want to create android app to control arduino car with bluetooth

my project has 2 steps:
Establish a connection between my phone and the arduino board
Use accelerometer sensor to move the car
The motion part i can handle it, but i can't find a way to use bluetooth. I just can't figure how to work with this Api.
What should i do to connect to the arduino and start sending signals to it?

Check this link out, its a Guide on Connecting Android Device with Arduino and Bluetooth
I'll just paste the Steps here, in case the link expires someday.
At the top of your source code, include these libs.
#include "SoftwareSerial.h"
#include "Bluetooth.h"
To start using it, at the top of your source declare a public variable to access it:
Bluetooth *blue = new Bluetooth(2, 3);
With Bluetooth(RX_Pin, TX_Pin)
The default pin is 1234, name is “PNGFramework” and baudrate is 9600
Now, on your Setup(), add the follow line:
void setup(){
Serial.begin(9600);
blue->setupBluetooth();
}
Send a message when we receive some data from Serial.
void loop(){
String msg = blue->Read();
if(msg.length() > 1){
Serial.print("Received: ");
Serial.println(msg);
}
if(Serial.available()){
blue->Send("Example message#");
}
}
In Android
First, create a bluetooth object, use the following code, make sure to use the same RobotName that you used in the Arduino project. (default is “PNGFramework”).
BluetoothArduino mBlue = BluetoothArduino.getInstance("PNGFramework");
To connect with the Arduino, add the command bellow:
mBlue.Connect();
Now, to read a message, run the command:
String msg = mBlue.getLastMessage();

Cannot send data from Android 5 to Bluetooth Low Energy module

I am writing an open source framework to use BLE Mini module with Android and iOS mobile devices using Unity engine.
This framework should allow to establish a connection between the mobile device and the BLE Mini module, and to send/receive data using it. The framework can be theoretically adapted to work with any BLE module.
The idea is to make the existing BLE Mini frameworks (available for iOS and Android) work in Unity engine, hence I am writing native plugins for iOS and Android that will allow Unity apps use the native frameworks.
The iOS plugin is working as expected, while I am having problems writing the Android plugin.
Everything works as expected except the fact that I cannot send data to my characteristic. If I send the data the BLE Mini module does not receive it.
The code controlling the BLE Mini data reception is correct because it works when iOS sends the data. So I am pretty sure the problem is in the Android plugin.
The Android plugin is composed by Android native code that can be found here:
https://github.com/giomurru/ble-framework/tree/master/AndroidPlugin/src/com/gmurru/bleframework
and by Unity c# code that can call the public java methods: https://github.com/giomurru/ble-framework/blob/master/Unity/Assets/BLE/BLEController.cs
The code contained in RBLGattAttributes.java and RBLService.java is correct because it is the framework provided by RedBearLab and I tested it and it works correctly with native Android apps.
The code in which I need help and that probably contains the bug is the one in BleFramework.java
The BleFramework class contains a series of functions that can be called by the Unity engine. The functions are called following this order:
Call the get static method BleFramework.getInstance() to get a singleton instance of the class BleFramework. This method returns one and only one instance of the BleFramework class.
After I have the instance of the class I can call the BleFramework methods using this instance (which is always the same instance).
The methods are called following this order:
1) Call the function _InitBLEFramework from Unity. The function should initialize the BLE framework. When the initialization is finished the Android plugin answer to Unity with a OnBleDidInitialize "Success" message.
2) If Unity receives the OnBleDidInitialize "Success" message, I can call the function _ScanForPeripherals from Unity. The function scans for available BLE modules peripherals. When the available peripherals are found the plugin answer to Unity with a OnBleDidCompletePeripheralScan "Success" message.
3) If Unity receives the OnBleDidCompletePeripheralScan "Success" message, I can call the function _GetListOfDevices to get the list of found devices.
4) Once I have the list of BLE module devices I found, I can try to connect to one of them using the function _ConnectPeripheralAtIndex(int peripheralIndex). When the _mGattUpdateReceiver receives RBLService.ACTION_GATT_SERVICES_DISCOVERED I can say the connection is established and I can let Unity know I am ready to send/receive data by sending a OnBleDidConnect "Success" message.
Up to here the plugin works as expected, and the connection is established.
The problem is when I try to send data in step 5.
5) When Unity receives the OnBleDidConnect "Success" message it is ready to send data through the established connection. Hence I try to send the data by using _SendData function in the plugin. Unfortunately it does not work.
This is the code:
public void _SendData(byte[] data)
{
Log.d(TAG,"_SendData: ");
BluetoothGattCharacteristic characteristic = _map.get(RBLService.UUID_BLE_SHIELD_TX);
Log.d(TAG, "Set data in the _characteristicTx");
byte[] tx = hexStringToByteArray("fefefe");
characteristic.setValue(tx);
Log.d(TAG, "Write _characteristicTx in the _mBluetoothLeService: " + tx[0] + " " + tx[1] + " " + tx[2]);
if (_mBluetoothLeService==null)
{
Log.d(TAG, "_mBluetoothLeService is null");
}
_mBluetoothLeService.writeCharacteristic(characteristic);
}
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i+1), 16));
}
return data;
}
Just for the purpose of testing I ignored byte[] data parameter and I try to send byte[] tx data that I create inside the _SendData function using hexStringToByteArray function (that I found in this StackOverflow post: Convert a string representation of a hex dump to a byte array using Java?)
I also tried to create the tx data as:
byte tx[] = new byte[] { (byte) 0xfe, (byte) 0xfe, (byte) 0xfe };
or to send the data directly like this:
public void _SendData(byte[] data)
{
Log.d(TAG,"_SendData: ");
BluetoothGattCharacteristic characteristic = _map.get(RBLService.UUID_BLE_SHIELD_TX);
Log.d(TAG, "Set data in the _characteristicTx");
characteristic.setValue(data);
Log.d(TAG, "Write _characteristicTx in the _mBluetoothLeService: " + data[0] + " " + data[1] + " " + data[2]);
if (_mBluetoothLeService==null)
{
Log.d(TAG, "_mBluetoothLeService is null");
}
_mBluetoothLeService.writeCharacteristic(characteristic);
}
In all the cases I failed to send the data.
I really can't understand why this is happening. The code I am using to search ble devices, establish connection, send receive data is very similar to the Android native samples available in ReadBearLab github page: https://github.com/RedBearLab/Android/tree/master/Examples
The only difference is that I am not extending Activity.
I tried to make BleFramework class an extension of Activity but it didn't work. The problem I had was that while BleFramework activity was running I was not able to send messages back to Unity using the UnityPlayer.UnitySendMessage function.

I answer my own question just for reference if anybody is interested in the solution I found.
I fixed the bug by updating the code to the latest Android APIs. Please check out the commits from June 15th 2019 to June 22nd 2019 in the repository if you are interested in the modifications. In particular the commit named "Android tx/rx works"
https://github.com/giomurru/ble-framework