The Society of Automotive Engineers (SAE) J1939 standards define a communication protocol for networking and diagnostics among electronic control units (ECUs) in heavy-duty vehicles. With advancements in vehicle electronics and the need for higher data transmission rates, the SAE introduced updates to the J1939 standard to incorporate the capabilities of the Controller Area Network with Flexible Data Rate (CAN FD). Two significant additions in this context are the SAE J1939-17 and SAE J1939-22 standards.
SAE J1939-17: CAN FD Physical Layer, 500 kbps/2 Mbps
Issued on December 30, 2020, SAE J1939-17 specifies a physical layer that utilizes the Flexible Data Rate Frame Format as defined in ISO 11898-1:2015. This standard is intended for light- and heavy-duty vehicles, both on- and off-road, as well as stationary applications using vehicle-derived components. The document defines a high-bandwidth physical layer with a base baud rate of 500 kbps and a flexible data rate of 2 Mbps, aiming to increase bandwidth and data transfer rates within the J1939 network. Reference: SAE International
SAE J1939-22: CAN FD Data Link Layer
Published on March 22, 2021, SAE J1939-22 describes the data link layer using the flexible data rate as defined in ISO 11898-1:2015. This standard facilitates the use of SAE J1939 networks utilizing CAN FD data frame format for communication use cases. The data link layer definition provides additional and unique capabilities compared to SAE J1939-21, taking advantage of the larger frame payload capability. The flexible data rate capability in CAN FD is implemented as a transport layer to allow for functional safety, cybersecurity, extended transport capability, and backward compatibility with SAE J1939DA. Reference: SAE International
Implications of CAN FD Integration
The integration of CAN FD into the J1939 protocol through these standards addresses the growing demand for higher data throughput in modern vehicle networks. CAN FD allows for larger data payloads and faster transmission speeds compared to the traditional CAN protocol, enhancing the efficiency of data exchange between ECUs. This advancement supports the increasing complexity of vehicle systems and the need for rapid communication to ensure optimal performance and safety.
Conclusion
The SAE J1939-17 and SAE J1939-22 standards represent significant advancements in the evolution of vehicle communication protocols. By incorporating CAN FD into the J1939 framework, these standards provide the necessary infrastructure to support the high-speed, high-capacity data transmission requirements of modern heavy-duty vehicles.
References for Further Research
- SAE J1939-17: CAN FD Physical Layer, 500 kbps/2 Mbps. SAE International. Link
- SAE J1939-22: CAN FD Data Link Layer. SAE International. Link
- “Specification for J1939 over CAN FD published.” Kvaser. Link
- “SAE J1939 Know-how.” Vector. Link
SAE J1939 ECU Programming & Vehicle Bus Simulation with Arduino
This book, authored by Wilfried Voss, provides an in-depth guide to implementing the SAE J1939 protocol stack using Arduino.
It includes numerous C/C++ code examples and detailed explanations of designing, transmitting, receiving, and processing J1939 data frames.
The book also covers simulating Electronic Control Units (ECUs) and offers practical projects such as a J1939 network scanner and a simple SAE J1939 to USB Gateway application. It’s an ideal resource for learning and implementing embedded applications with the SAE J1939 protocol stack. More information…
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