OBD-II Diagnostic Dongle

OBD-II Vehicle Diagnostics Dongle

Smart Vehicle Diagnostics & Real-Time Driving Insights

Silentronics developed a compact OBD-II Vehicle Diagnostics Dongle that plugs directly into a vehicle’s OBD-II port and provides real-time diagnostics, live vehicle data, DTC fault code reading, trip analytics, and service reminders through a connected mobile application. The solution combines embedded hardware, Bluetooth Low Energy (BLE) connectivity, firmware intelligence, and a user-friendly mobile dashboard to enable smarter vehicle monitoring and maintenance.

☞ System Architecture

The OBD-II diagnostics dongle acts as a smart in-vehicle interface between the car’s ECU/OBD-II port, the mobile application, and optional cloud analytics services. It captures vehicle data, interprets fault codes, and streams live diagnostics to the mobile app over BLE.

☞ Hardware Development

The dongle hardware was designed as a compact, plug-and-play automotive diagnostics device optimized for vehicle-side communication, low power operation, reliable BLE connectivity, and portable deployment.

Core Hardware Components

• Main MCU: ESP32 / STM32
• OBD-II Connector Interface
• ELM327 / OBD Protocol Interface Section
• BLE 5.0 Wireless Connectivity
• Status LED Indicators
• Compact Enclosure for Vehicle Use
• Power Regulation for Automotive Input

Hardware Design Highlights

• Plug-and-play OBD-II vehicle interface
• Compact and portable mechanical form factor
• Low power electronics for in-vehicle operation
• Status LEDs for power, OBD activity, and BLE connection
• Automotive-friendly input power architecture
• Designed for stable BLE communication with mobile devices

☞ Firmware Development

Custom embedded firmware was developed to enable OBD-II communication, vehicle data acquisition, protocol parsing, BLE data transmission, DTC management, and mobile app integration.

Firmware Features

• OBD-II PID polling and vehicle parameter acquisition
• Real-time live data streaming over BLE
• Diagnostic Trouble Code (DTC) reading
• DTC interpretation and clear command handling
• Vehicle health status monitoring
• Service reminder and usage-based alert logic
• Trip analytics data collection and preprocessing
• BLE communication with mobile application
• Power/status LED control and device state management
• Connection handling and session management

Supported Live Vehicle Parameters

• Vehicle Speed
• Engine RPM
• Coolant Temperature
• Fuel Level
• Intake Air Temperature
• Battery Voltage
• Throttle Position
• Engine Load

☞ Mobile Application

A dedicated mobile application was developed to provide an intuitive dashboard for vehicle monitoring, diagnostics, DTC viewing, and trip insights. The app communicates with the dongle over Bluetooth 5.0 and presents the data in a clear, user-friendly format.

Mobile Features

• Vehicle Dashboard with real-time metrics
• Live data screen for detailed parameter monitoring
• DTC fault code display with descriptions
• Clear fault codes from the app
• Trip analytics and driving pattern insights
• Service reminder notifications
• BLE device pairing and connection management
• Vehicle health monitoring from smartphone

Example Mobile Dashboard Data

• Speed
• RPM
• Coolant Temperature
• Fuel Level
• Battery Voltage
• Intake Air Temperature
• Throttle Position
• Engine Load

Mobile Compatibility

• Android
• iOS

☞ Challenges Solved

• Built a compact plug-and-play diagnostics device for direct OBD-II vehicle interfacing.
• Supported multiple automotive OBD-II communication protocols within a single product.
• Enabled real-time vehicle monitoring over Bluetooth Low Energy.
• Simplified fault code reading and clearing through a consumer-friendly mobile app.
• Delivered trip analytics and service reminder functionality beyond basic diagnostics.
• Designed a low-power, portable hardware platform suitable for everyday in-vehicle use.
• Combined embedded hardware, firmware, BLE communication, and mobile application into one unified solution.

☞ Tools & Technologies

• ESP32 / STM32  • Bluetooth Low Energy (BLE 5.0)  • OBD-II / SAE J1979  • CAN • J1850 VPW / PWM   • Embedded C / Firmware Development  • Mobile App Development (Android / iOS)  • Automotive Diagnostics  • Trip Analytics & Data Visualization