Kvaser proposes backward-compatible, high-bandwidth CAN version

November 20, 2013 // By Christoph Hammerschmidt
As an intermediate step on the transition to the high-performance CAN bus version with flexible data rate (CAN-FD), Swedish technology company Kvaser AB has presented a new CAN version, dubbed CAN-EF (Enhanced Format). The beauty of CAN-EF: Unlike CAN-FD, it offers higher bandwidth without giving up backward compatibility.

As automotive software applications require more bandwidth for data communications among ECUs inside the car, a new, speedier version of the venerable CAN bus is currently under development by CAN inventor Bosch GmbH. This version, CAN FD, will provide a highly efficient method of increasing CAN data throughput, by increasing the number of bytes in each CAN frame (from 8 to 64 bytes), whilst making the CAN frames shorter. However, this technology is not compatible with existing CAN controllers; systems and modules have to be re-designed.

At the 14th International CAN Conference in Paris, Kvaser pressed ahead by introducing CAN-EF. This version achieves higher data rate communication than CAN by packing the extra bits into the CAN-frames in such way that they can be received by legacy CAN controllers, ensuring backwards compatibility with existing CAN infrastructure.

According to Kvaser president Lars-Berno Fredriksson, CAN-EF could facilitate the industry's move to CAN-FD. Since the development and standardization of CAN-FD is expected quite a while - currently the flexible data rate CAN is in the process of being integrated within ISO 11898-1 - CAN-EF could give CAN users quicker and simpler access to greater data rates in the meantime.

The performance of CAN-EF would be within the range of 50-90% of CAN-FD in similar circumstances. Kent Lennartsson, Kvaser’s Hardware Development Manager, says: “From a silicon vendor’s point of view, a great deal of the logic would be common across CAN, CAN-EF and CAN-FD, making it possible to combine all logic into one unit with a minor increase in gate count compared to CAN-FD.”

CAN-EF works by hiding the high-speed data from the legacy CAN modules, allowing CAN-EF modules to be installed into any system to communicate at a higher bit-rate without interfering with any connected CAN module in use today. This would allow users to replace modules gradually to achieve a progressive increase in data throughput, rather than suddenly render all existing CAN