UDS Protocol Stack & DoCAN Implementation for RH850 ECU

Snapshot

RAPIDSEA partnered with a leading Indian Tier 1 supplier to integrate a robust diagnostic layer into their Electro-magnetic retarder ECU. By deploying our pre-certified UDS Protocol Stack, the team achieved Start of Production (SoP) in just 6 weeks, reducing the typical development lifecycle by over 50% while meeting stringent OEM security standards.

Customer Profile

The customer is a premier Tier 1 automotive supplier based in India, specializing in advanced braking systems and electronic control units for commercial and passenger vehicles. They are a preferred partner for global OEMs, known for delivering high-reliability safety components.

Business Context

Modern commercial vehicles require sophisticated diagnostic capabilities for maintenance and safety audits. The customer needed to upgrade their Electro-magnetic retarder ECU to support the Unified Diagnostic Services (UDS) protocol. The project was driven by a strict OEM mandate to implement standardized diagnostics, secure data access, and over-the-wire flash programming to ensure long-term field maintainability.

Key Challenges

Tight Time-to-Market: The transition from development to SoP was constrained to a sub-two-month window.
Strict Security Norms: Compliance with OEM-specific security algorithms was mandatory to prevent unauthorized ECU access.
Hardware Integration: Ensuring seamless communication between the diagnostic stack and the specific Renesas RH850 architecture.
Reliability in Critical Systems: The retarder is a safety-critical component; any diagnostic overhead could not interfere with real-time control loops.

Target Platform

The project targeted the Renesas RH850/F1KM-S1, a high-end 32-bit automotive microcontroller designed for body applications. It features advanced functional safety (ISO 26262) support, integrated CAN-FD controllers, and enhanced security modules, making it an ideal but complex target for diagnostic integration.

Why RAPIDSEA

RAPIDSEA was selected because of its highly modular architecture and hardware-agnostic HAL (Hardware Abstraction Layer). Unlike generic stacks, RAPIDSEA provides a "ready-to-use" proven solution specifically optimized for the RH850 family, ensuring that developers spend time on application logic rather than debugging low-level driver conflicts.

RAPIDSEA Features Used

RAPIDSEA DoCAN Stack: ISO 15765-2 compliant transport protocol.
RAPIDSEA UDS Server: ISO 14229 compliant diagnostic services.
Security Access Module: Implementation of Service $27 for seed-key authentication.
Flash Programming Routines: Supporting Service $34 (Request Download) and $36 (Transfer Data).
DID Manager: For configuration and runtime telemetry collection.

Solution Overview

The Foundation: DoCAN and HAL Customization

The implementation began with the deployment of the RAPIDSEA DoCAN stack. In the automotive world, the Data Link layer is the backbone of communication. Our engineers utilized the well-defined Hardware Abstraction Layer (HAL) to map the stack to the RH850’s CAN controllers. Because the RAPIDSEA stack is built with modularity as a priority, the customization of the HAL layer was completed within days. This ensured that the ISO 15765-2 transport protocol could handle multi-frame messages and flow control with the precision required for high-speed diagnostic communication.

UDS Stack Integration and Service Implementation

Once the DoCAN layer was verified, the UDS Protocol Stack (ISO 14229) was ported. The RAPIDSEA UDS server uses a callback-based architecture, which allows developers to hook into diagnostic requests without rewriting the core engine. We implemented the mandatory diagnostic services, including Diagnostic Session Control ($10) and Tester Present ($3E).

To meet the specific needs of the Electro-magnetic retarder, we configured a comprehensive set of Data Identifiers (DIDs). These DIDs allow the OEM to pull real-time information such as coil temperatures, current consumption, and error logs, as well as write configuration parameters during end-of-line (EoL) testing.

Advanced Security and Flash Programming

Safety and security were paramount. We integrated a robust Security Access ($27) service, customized to the OEM’s specific encryption and seed-key requirements. This ensures that sensitive operations like recalibrating the retarder’s force or updating firmware cannot be performed by unauthorized tools.

Furthermore, we implemented the Flash Programming routines. By enabling the download feature through UDS, we provided the customer with the ability to update the ECU firmware via the CAN bus. This involved careful management of memory sectors and integration with the RH850’s internal flash libraries, ensuring that the bootloader and the application-level UDS stack worked in perfect harmony.

Final Validation and SoP

The final phase involved rigorous testing against the OEM's diagnostic test suite. Because the RAPIDSEA stack is pre-validated, the "plug-and-play" nature of the software meant that the integration bugs were virtually non-existent. The entire project, from initial HAL mapping to the final security handshake, was finalized and pushed to Start of Production in just 6 weeks.

Engineering Impact

Rapid Development: Achieved a fully functional, production-ready diagnostic layer in 6 weeks, compared to the industry average of 14–16 weeks.
Zero Latency Overhead: The modular stack footprint ensured that the retarder's real-time safety functions remained unaffected during active diagnostic sessions.
100% OEM Compliance: Fully met the end-customer’s security and flash programming specifications on the first submission.
Scalability: The modular design allows the Tier 1 supplier to reuse the same UDS implementation across other RH850-based ECU variants with minimal changes.

Conclusion

Are you looking to accelerate your ECU's diagnostic compliance?

If your project requires a high-performance UDS Protocol Stack or a custom DoCAN implementation for Renesas, Infineon, or ST platforms, RAPIDSEA can help you reach SoP faster.