Flutter OBD2 Plugin: Connect Your Apps to Vehicle Diagnostics

Integrating On-Board Diagnostics II (OBD-II) functionality into your Flutter application opens up a world of possibilities for automotive diagnostics, data monitoring, and vehicle performance analysis. This guide introduces the obd_connection_ii Flutter plugin, a powerful tool for establishing seamless communication between your Flutter app and vehicle systems via OBD-II.

Getting Started with Flutter OBD2 Integration

To begin leveraging the obd_connection_ii plugin in your Flutter project, you’ll need to add it as a dependency. The most direct method is by referencing the Git repository:

```yaml
dependencies:
  flutter:
    sdk: flutter
  obd2_plugin:
    git:
      url: git://github.com/begaz/OBDII.git
      ref: main

Alternatively, you can manually integrate the plugin by following these steps:

1. Download the Plugin: Obtain the plugin files directly from the GitHub repository.
2. Plugin Placement: Place the downloaded plugin folder within your main Flutter project directory.
3. Extraction and Renaming: Extract the contents of the downloaded folder and rename it to obd2_plugin.
4. Dependency Declaration: Update your pubspec.yaml file to include the local path dependency:

```yaml
dependencies:
  flutter:
    sdk: flutter
  obd2_plugin:
    path: ../obd2_plugin/

After configuring the dependency in pubspec.yaml, execute the following command in your terminal to fetch the plugin:

flutter pub get

This command ensures that the plugin is correctly added to your project and ready for use.

Utilizing the OBD2 Plugin in Your Flutter App

Once the plugin is integrated, you can start interacting with OBD-II data within your Flutter application.

Initializing the OBD2 Plugin

First, instantiate the Obd2Plugin class to gain access to the plugin’s functionalities:

Obd2Plugin obd2 = Obd2Plugin();

Checking Bluetooth Status

Before establishing an OBD-II connection, it’s essential to verify Bluetooth status on the device. The following line of code prompts the user to enable Bluetooth if it’s currently disabled:

bool enabled = await obd2.enableBluetooth;

The enableBluetooth method returns true if Bluetooth is already enabled or successfully enabled upon user request.

Verifying Active Connection

To check if an active OBD-II connection already exists, use the hasConnection method:

bool connected = await obd2.hasConnection;

This method returns true if a connection is active, and false otherwise.

Discovering Bluetooth Devices

The obd2_plugin provides methods to discover Bluetooth devices for connection.

To retrieve a list of paired Bluetooth devices:

List<BluetoothDevice> devices = await obd2.getPairedDevices;

To scan for nearby Bluetooth devices:

List<BluetoothDevice> devices = await obd2.getNearbyDevices;

For a combined list of both paired and nearby devices:

List<BluetoothDevice> devices = await obd2.getNearbyPairedDevices;

Establishing a Connection to a Bluetooth Device

To connect to a specific Bluetooth device from the discovered list, use the getConnection method:

obd2.getConnection(devices[index], (connection) {
  print("connected to bluetooth device.");
}, (message) {
  print("error in connecting: $message");
});

This method takes a BluetoothDevice object, a success callback function (invoked upon successful connection), and an error callback function (invoked if connection fails).

Receiving Real-time OBD-II Data

To listen for and process real-time data streamed from the OBD-II adapter, use the setOnDataReceived method:

obd2.setOnDataReceived((command, response, requestCode) {
  print("$command => $response");
});

The setOnDataReceived method should be initialized only once in your application. To check if it has already been initialized, use:

await obd2.isListenToDataInitialed;

Sending Commands and Configuring OBD-II Parameters

The obd2_plugin allows sending custom commands and configuring OBD-II parameters using JSON format.

Configuring OBD-II with JSON

The configObdWithJSON method facilitates sending configuration commands to the OBD-II adapter using a JSON string:

await obd2.configObdWithJSON(json, {int requestCode});

This method returns an integer value representing the recommended waiting time in milliseconds before sending subsequent commands. It is advisable to implement a delay using Future.delayed as demonstrated below:

loading.start();
await Future.delayed(Duration(milliseconds: await obd2.configObdWithJSON(json)), () {
  loading.stop();
});

JSON Configuration Examples

The plugin supports three primary methods for sending data, each utilizing JSON format strings: getParamsFromJSON, getDTCFromJSON, and configObdWithJSON. Ensure your JSON strings adhere to the specified formats.

Configuration JSON Example

[
  { "command": "AT Z", "description": "", "status": true },
  { "command": "AT E0", "description": "", "status": true },
  { "command": "AT SP 0", "description": "", "status": true },
  { "command": "AT SH 81 10 F1", "description": "", "status": true },
  { "command": "AT H1", "description": "", "status": true },
  { "command": "AT S0", "description": "", "status": true },
  { "command": "AT M0", "description": "", "status": true },
  { "command": "AT AT 1", "description": "", "status": true },
  { "command": "01 00", "description": "", "status": true }
]

Parameter JSON Example

[
  { "PID": "AT RV", "length": 4, "title": "Battery Voltage", "unit": "V", "description": "<str>", "status": true },
  { "PID": "01 0C", "length": 2, "title": "Engine RPM", "unit": "RPM", "description": "<double>, (( [0] * 256) + [1] ) / 4", "status": true },
  { "PID": "01 0D", "length": 1, "title": "Speed", "unit": "Kh", "description": "<int>, [0]", "status": true },
  { "PID": "01 05", "length": 1, "title": "Engine Temp", "unit": "°C", "description": "<int>, [0] - 40", "status": true },
  { "PID": "01 0B", "length": 1, "title": "Manifold absolute pressure", "unit": "kPa", "description": "<int>, [0]", "status": true }
]

Diagnostic Trouble Codes (DTC) JSON Example

[
  { "id": 1, "created_at": "2021-12-05T16:33:18.965620Z", "command": "03", "response": "6", "status": true },
  { "id": 7, "created_at": "2021-12-05T16:35:01.516477Z", "command": "18 FF 00", "response": "", "status": true },
  { "id": 6, "created_at": "2021-12-05T16:34:51.417614Z", "command": "18 02 FF FF", "response": "", "status": true },
  { "id": 5, "created_at": "2021-12-05T16:34:23.837086Z", "command": "18 02 FF 00", "response": "", "status": true },
  { "id": 4, "created_at": "2021-12-05T16:34:12.496052Z", "command": "18 00 FF 00", "response": "", "status": true },
  { "id": 3, "created_at": "2021-12-05T16:33:38.323200Z", "command": "0A", "response": "6", "status": true },
  { "id": 2, "created_at": "2021-12-05T16:33:28.439547Z", "command": "07", "response": "6", "status": true },
  { "id": 34, "created_at": "2021-12-05T16:41:25.883408Z", "command": "17 FF 00", "response": "", "status": true },
  { "id": 35, "created_at": "2021-12-05T16:41:38.901888Z", "command": "13 FF 00", "response": "", "status": true },
  { "id": 36, "created_at": "2021-12-05T16:41:51.040962Z", "command": "19 02 AF", "response": "", "status": true },
  { "id": 37, "created_at": "2021-12-05T16:42:01.384228Z", "command": "19 02 AC", "response": "", "status": true },
  { "id": 38, "created_at": "2021-12-05T16:42:11.770741Z", "command": "19 02 8D", "response": "", "status": true },
  { "id": 39, "created_at": "2021-12-05T16:42:28.443368Z", "command": "19 02 23", "response": "", "status": true },
  { "id": 40, "created_at": "2021-12-05T16:42:39.200378Z", "command": "19 02 78", "response": "", "status": true },
  { "id": 41, "created_at": "2021-12-05T16:42:50.444404Z", "command": "19 02 08", "response": "", "status": true },
  { "id": 42, "created_at": "2021-12-05T16:43:00.466739Z", "command": "19 0F AC", "response": "", "status": true },
  { "id": 43, "created_at": "2021-12-05T16:43:10.645120Z", "command": "19 0F 8D", "response": "", "status": true },
  { "id": 44, "created_at": "2021-12-05T16:43:25.257023Z", "command": "19 0F 23", "response": "", "status": true },
  { "id": 45, "created_at": "2021-12-05T16:43:36.567099Z", "command": "19 D2 FF 00", "response": "", "status": true },
  { "id": 46, "created_at": "2021-12-05T17:15:56.352652Z", "command": "19 C2 FF 00", "response": "", "status": true },
  { "id": 47, "created_at": "2021-12-05T17:16:17.567797Z", "command": "19 FF FF 00", "response": "", "status": true }
]

After successfully configuring OBD-II parameters using configObdWithJSON, you can access the real-time data received from the vehicle’s system within the setOnDataReceived callback function.

Developed with ❤️ by Begaz.