Design and Development of Automotive On-Board Diagnostic Protocol System

Abstract- The increasing complexity of modern vehicles necessitates the use of multiple Electronics Control Units (ECUs) to manage and monitor various functions. Communication between these ECUs is facilitated by the Controller Area Network (CAN) protocol, which handles the Physical and Data Link layers of the OSI model but lacks advanced diagnostic capabilities. To address this, standardized diagnostic protocols such as On-Board Diagnostics (OBD2) have been developed, providing a comprehensive framework for fault detection and in-vehicle communication. This paper presents the design and implementation of the OBD2 protocol on an embedded system using STM32F407 microcontrollers. The project aims to establish a diagnostic communication system between ECUs and Tester Tool. Primary function of this ECU is to measure ambient temperature and Throttle Position. ECU and Tester tools are connected via a CAN bus. The implementation leverages the ISO 15031 standard to ensure reliable and standardized diagnostic services. Keywords: On-Board Diagnostics (OBD2), ISO 15031, Electronic Control Unit (ECU), Body Control Module (BCM), Light Control Module (LCM), Controller Area Network (CAN), Diagnostic Trouble Code (DTC), Routine Control Identifier (RID), Data Identifier (DID), ISO-TP (Transport Protocol)