Shiny.Obd

A .NET library for communicating with vehicles through OBD-II (On-Board Diagnostics) adapters. Supports ELM327 and OBDLink (STN) adapters over pluggable transports, starting with Bluetooth LE.

Documentation

Features

• Command-object pattern — OBD commands are objects, not methods. Pass built-in commands or create your own for custom PIDs.
• Generic return types — each command declares its return type (int, double, string, TimeSpan, etc.) with compile-time safety.
• Pluggable transports — IObdTransport abstracts the communication channel. Ship with BLE; add WiFi or USB later.
• Adapter auto-detection — detects ELM327 vs OBDLink (STN) adapters via ATI and runs the appropriate initialization sequence.
• Adapter profiles — IObdAdapterProfile lets you define custom init sequences. Built-in profiles for ELM327 and OBDLink.
• Task-based async — fully async/await throughout, no Reactive Extensions required in consuming code.
• 9 standard commands included — speed, RPM, coolant temp, throttle, fuel level, engine load, intake air temp, runtime, and VIN.

Projects

Package	Target	Description
Shiny.Obd	net10.0	Core library — commands, connection, transport abstraction
Shiny.Obd.Ble	net10.0	BLE transport using Shiny.BluetoothLE

Quick Start

1. Install packages

<!-- Core (always needed) -->
<PackageReference Include="Shiny.Obd" />

<!-- BLE transport -->
<PackageReference Include="Shiny.Obd.Ble" />

2. Connect and query

using Shiny.Obd;
using Shiny.Obd.Ble;
using Shiny.Obd.Commands;

// Create BLE transport (scans for adapter automatically)
var transport = new BleObdTransport(bleManager, new BleObdConfiguration
{
    DeviceNameFilter = "OBDLink" // optional: filter by adapter name
});

// Create connection (auto-detects adapter type)
var connection = new ObdConnection(transport);
await connection.Connect();

// Execute commands
var speed = await connection.Execute(StandardCommands.VehicleSpeed);    // int (km/h)
var rpm = await connection.Execute(StandardCommands.EngineRpm);        // int
var vin = await connection.Execute(StandardCommands.Vin);              // string

Console.WriteLine($"Speed: {speed} km/h, RPM: {rpm}, VIN: {vin}");

Architecture

┌─────────────────────────────────────────────────┐
│                 Your App                        │
│   await connection.Execute(StandardCommands.*)  │
└──────────────────────┬──────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────┐
│              ObdConnection                      │
│  • Adapter detection (ATI probe)                │
│  • Profile-based initialization                 │
│  • ELM327 response parsing (hex → bytes)        │
│  • Error handling (NO DATA, UNABLE TO CONNECT)  │
└──────────────────────┬──────────────────────────┘
                       │
┌──────────────────────▼──────────────────────────┐
│             IObdTransport                       │
│  Pluggable transport layer                      │
│  ┌──────────────┐  ┌────────┐  ┌─────────┐     │
│  │ BleObdTransport│  │ WiFi  │  │  USB    │     │
│  │ (Shiny BLE)  │  │(future)│  │(future) │     │
│  └──────────────┘  └────────┘  └─────────┘     │
└─────────────────────────────────────────────────┘

Commands

Standard Commands

All standard commands are available as singletons via StandardCommands:

Command	Mode	PID	Return Type	Unit
VehicleSpeed	01	0D	int	km/h
EngineRpm	01	0C	int	RPM
CoolantTemperature	01	05	int	°C
ThrottlePosition	01	11	double	%
FuelLevel	01	2F	double	%
CalculatedEngineLoad	01	04	double	%
IntakeAirTemperature	01	0F	int	°C
RuntimeSinceStart	01	1F	TimeSpan	—
Vin	09	02	string	—

var speed = await connection.Execute(StandardCommands.VehicleSpeed);
var rpm = await connection.Execute(StandardCommands.EngineRpm);
var coolant = await connection.Execute(StandardCommands.CoolantTemperature);
var throttle = await connection.Execute(StandardCommands.ThrottlePosition);
var fuel = await connection.Execute(StandardCommands.FuelLevel);
var load = await connection.Execute(StandardCommands.CalculatedEngineLoad);
var intakeTemp = await connection.Execute(StandardCommands.IntakeAirTemperature);
var runtime = await connection.Execute(StandardCommands.RuntimeSinceStart);
var vin = await connection.Execute(StandardCommands.Vin);

Custom Commands

Implement IObdCommand<T> directly for full control, or extend ObdCommand<T> for standard Mode/PID commands.

Extending ObdCommand<T> (standard Mode/PID pattern)

// Barometric pressure (Mode 01, PID 0x33) — single byte, value in kPa
public class BarometricPressureCommand : ObdCommand<int>
{
    public BarometricPressureCommand() : base(0x01, 0x33) { }
    protected override int ParseData(byte[] data) => data[0];
}

// Usage
var pressure = await connection.Execute(new BarometricPressureCommand());

The ObdCommand<T> base class automatically:

• Generates RawCommand from Mode + PID (e.g. "0133")
• Validates the response header (mode echo + PID match)
• Strips the 2-byte header before calling your ParseData

Implementing IObdCommand<T> (full control)

// Completely custom command with non-standard response format
public class CustomDiagnosticCommand : IObdCommand<string>
{
    public string RawCommand => "2101";  // manufacturer-specific

    public string Parse(byte[] data)
    {
        // You receive ALL response bytes — parse however you need
        return BitConverter.ToString(data);
    }
}

Adapter Profiles

Auto-Detection (default)

When you create ObdConnection(transport) without a profile, Connect() sends ATI to identify the adapter:

ATI Response Contains	Detected As	Profile Used
"ELM327"	ObdAdapterType.Elm327	Elm327AdapterProfile
"STN"	ObdAdapterType.ObdLink	ObdLinkAdapterProfile
Anything else	ObdAdapterType.Unknown	Elm327AdapterProfile

var connection = new ObdConnection(transport);
await connection.Connect();

// Check what was detected
Console.WriteLine(connection.DetectedAdapter?.RawIdentifier); // "ELM327 v1.5"
Console.WriteLine(connection.DetectedAdapter?.Type);          // Elm327

Explicit Profile

Skip detection by providing a profile:

var connection = new ObdConnection(transport, new ObdLinkAdapterProfile());
await connection.Connect(); // uses OBDLink init, no ATI probe

Built-in Profiles

Elm327AdapterProfile — Standard initialization:

ATZ    → Reset
ATE0   → Echo off
ATL0   → Linefeed off
ATS1   → Spaces on
ATH0   → Headers off
ATSP0  → Auto protocol

ObdLinkAdapterProfile — Extends ELM327 with STN-specific optimizations:

(all ELM327 commands above)
STFAC  → Reset to factory defaults
ATCAF1 → CAN auto formatting on

Custom Profiles

public class MyAdapterProfile : IObdAdapterProfile
{
    public string Name => "MyAdapter";

    public async Task Initialize(IObdConnection connection, CancellationToken ct = default)
    {
        await connection.SendRaw("ATZ", ct);
        await Task.Delay(500, ct);
        await connection.SendRaw("ATE0", ct);
        await connection.SendRaw("ATSP6", ct);  // force CAN 11-bit 500kbaud
        // ... any adapter-specific commands
    }
}

Device Discovery

Before connecting, scan for available OBD adapters with IObdDeviceScanner:

using Shiny.Obd;
using Shiny.Obd.Ble;

var scanner = new BleObdDeviceScanner(bleManager, new BleObdConfiguration
{
    DeviceNameFilter = "OBD"
});

var cts = new CancellationTokenSource();
await scanner.Scan(device =>
{
    Console.WriteLine($"Found: {device.Name} ({device.Id})");
    // device.NativeDevice is IPeripheral for BLE
}, cts.Token);

Each discovered device is an ObdDiscoveredDevice with Name, Id, and NativeDevice. Pass it directly to BleObdTransport:

var transport = new BleObdTransport(device, new BleObdConfiguration());
var connection = new ObdConnection(transport);
await connection.Connect();

DI Registration

Register BLE OBD services in one call:

using Shiny;

builder.Services.AddBluetoothLE(); // Shiny BLE platform registration
builder.Services.AddShinyObdBluetoothLE(new BleObdConfiguration
{
    DeviceNameFilter = "OBD"
});

AddShinyObdBluetoothLE registers BleObdConfiguration and IObdDeviceScanner (BleObdDeviceScanner). You must also call AddBluetoothLE() for platform BLE support.

## BLE Transport

### Configuration

```csharp
var config = new BleObdConfiguration
{
    // GATT UUIDs — defaults work for most ELM327 BLE clones
    ServiceUuid = "FFF0",
    ReadCharacteristicUuid = "FFF1",    // notifications (RX from adapter)
    WriteCharacteristicUuid = "FFF2",   // write commands (TX to adapter)

    // Optional: filter scan results by device name
    DeviceNameFilter = "OBDLink",

    // Timeout for a single command response
    CommandTimeout = TimeSpan.FromSeconds(10)
};

Using a Discovered Device

Use BleObdDeviceScanner to find adapters, then pass the selected device directly:

ObdDiscoveredDevice device = /* from scanner */;
var transport = new BleObdTransport(device, new BleObdConfiguration());

Using a Pre-Scanned Peripheral

If you've already discovered the BLE peripheral (e.g. from a scan UI):

IPeripheral peripheral = /* from your scan */;
var transport = new BleObdTransport(peripheral, new BleObdConfiguration());

Auto-Scan

Let the transport scan for the first matching device:

IBleManager bleManager = /* from DI */;
var transport = new BleObdTransport(bleManager, new BleObdConfiguration
{
    DeviceNameFilter = "OBDII"
});

Raw Commands

Send arbitrary AT or OBD commands:

// AT commands
var version = await connection.SendRaw("ATI");      // "ELM327 v1.5"
var protocol = await connection.SendRaw("ATDPN");   // current protocol number
var voltage = await connection.SendRaw("ATRV");     // battery voltage

// Raw OBD hex commands
var response = await connection.SendRaw("0100");    // supported PIDs [01-20]

Error Handling

ObdException is thrown for adapter-level errors:

try
{
    var speed = await connection.Execute(StandardCommands.VehicleSpeed);
}
catch (ObdException ex) when (ex.Message.Contains("No data"))
{
    // Vehicle not responding to this PID (engine off, unsupported PID, etc.)
}
catch (ObdException ex) when (ex.Message.Contains("Unable to connect"))
{
    // Adapter can't reach the vehicle ECU
}

The ObdCommand<T> base class also validates response headers and throws ObdException on mode/PID mismatches.

Implementing a Custom Transport

Implement IObdTransport to add WiFi, USB, or any other communication channel:

public class WifiObdTransport : IObdTransport
{
    public bool IsConnected { get; private set; }

    public async Task Connect(CancellationToken ct = default)
    {
        // Connect to ELM327 WiFi adapter (typically 192.168.0.10:35000)
    }

    public Task Disconnect() { /* ... */ }

    public async Task<string> Send(string command, CancellationToken ct = default)
    {
        // Send command, collect response until '>' prompt, return the text
    }

    public ValueTask DisposeAsync() { /* ... */ }
}

The Send method must:

1. Write the command string to the adapter
2. Read the response until the > prompt character
3. Return the response text (without the > prompt)