Real-Time CAN Gateway Communication
Reliable Communication Between Galvanically Isolated Embedded Controllers
1) Project Overview
The project focused on the development of reliable real-time communication software for an embedded control unit consisting of multiple hardware boards connected via CAN.
One dedicated communication board acted as the interface between the external vehicle CAN network and the distributed internal control system. Its responsibility was to receive external CAN messages, validate them, apply message filtering and distribute relevant information to the remaining controller boards.
The communication layer became a central part of the overall firmware and had to guarantee deterministic behavior under real-time conditions.
2) Engineering Challenge
The embedded system consisted of several galvanically isolated controller boards. Since the processors could not communicate through shared memory or direct hardware interfaces, all real-time data exchange had to be performed exclusively via CAN communication.
The software therefore had to ensure:
- deterministic interrupt handling,
- reliable message transfer between external and internal CAN communication,
- message filtering and routing,
- real-time synchronization between hardware boards,
- robust behavior under high CAN bus load,
- seamless integration into the existing production firmware.
3) Communication Architecture
The basic communication flow can be described as follows:
External CAN Network → Communication Board → Internal CAN Network → Distributed Controller Boards
The communication board processed external CAN messages, applied the required filtering logic and broadcasted relevant information to the internal boards. Since the system relied on CAN as the only communication path between isolated controllers, timing behavior and message integrity were critical.
4) My Responsibilities
- development of the embedded CAN communication layer,
- implementation of interrupt-driven firmware routines,
- register-level programming of communication functions,
- implementation of message filtering mechanisms,
- buffer management and synchronization,
- integration into the existing main firmware,
- communication performance optimization,
- system verification and validation,
- technical documentation in German and English.
5) Real-Time Firmware Implementation
The implementation was close to the hardware and required careful handling of microcontroller registers, interrupt routines and memory-related communication structures. Special attention was given to interrupt latency, deterministic execution and safe message processing under burst traffic conditions.
The developed communication logic was integrated into the existing production firmware and became part of the operational embedded software of the control unit.
6) Automated Validation with CANoe and CAPL
Reliable communication cannot simply be assumed — it must be demonstrated. To verify the implementation under worst-case conditions, I developed a reusable automated validation environment using Vector CANoe and CAPL.
The CAPL tool was designed to:
- generate configurable burst communication,
- simulate high CAN bus load,
- monitor incoming and outgoing messages,
- count transmitted and received CAN messages,
- detect lost or delayed messages,
- visualize communication counters and statistics in real time.
Instead of relying on manual observation, the validation environment provided objective evidence that the communication software operated correctly under heavy communication load.
7) Technical Documentation and Handover
At the completion of the project, I prepared comprehensive technical documentation in both German and English. The documentation explained the firmware concept, the communication behavior and the use of the CAPL-based validation tool.
The documentation covered:
- communication concept and CAN message flow,
- integration into the main firmware,
- configuration of the CAPL test environment,
- adjustment of burst message parameters,
- interpretation of graphical counters and communication statistics,
- operating instructions for automated verification.
8) Results
- Reliable real-time CAN communication between isolated embedded controllers
- Deterministic interrupt-based firmware behavior
- Robust external CAN message processing and filtering
- Successful integration into the production firmware
- Configurable automated burst testing with CANoe/CAPL
- Graphical verification of incoming and outgoing communication counters
- Objective proof of communication integrity before final handover
- Complete technical documentation in German and English
9) Technologies
C · CAN · CAPL · Vector CANoe · Embedded Firmware · Interrupts · Microcontroller Registers · Real-Time Systems · Message Filtering · Integration Testing · Automotive Embedded Systems
This project combined low-level embedded firmware development with real-time communication design, automated validation and structured technical handover.