End of December, the nonprofit CiA (CAN in Automation) international users’ and manufacturers’ group has established the CAN XL Special Interest Group (SIG). Several OEMs, Tier1s, chipmakers, and other interested parties including tool suppliers discussed in a two-days meeting the desired features of the CAN XL data link layer. The 35 participants elected Dr. Arthur Mutter (Bosch) as chairman; Reiner Zitzmann (CEO of CiA) is the SIG secretary.

The SIG experts requested for the CAN XL protocol backwards compatibility with CAN FD. In order to keep the data link layer as simple as possible, only one frame format with an 11-bit priority identifier is supported. The CAN XL data link layer is intended for TCP/IP communication, simple radar sensors, and eCall devices.

“In this two-days inaugural meeting, the experts evaluated already very detailed protocol features,” said Holger Zeltwanger, CiA Managing Director. Additionally, the participants discussed about the requirements on the Physical Media Attachment (PMA) sub-layer – normally implemented in a transceiver chip. The desired speed is in minimum 10 Mbit/s. The SIC (signal improvement circuitry) transceivers as specified in CiA 601-4 already achieves 8 Mbit/s. In particular, the edge symmetry and the voltage amplitude need to be improved to go beyond nowadays limits. “Perhaps we can learn from the Flexray physical layer,” said Zeltwanger.

The SIG will also organize plug fests to prove the prototype implementations. First FPGA implementations of the CAN XL protocol could be used for such interoperability tests. “If we are fast, we can schedule a first plug fest beginning of 2020,” said Zeltwanger.