Automation CAN group plans permanent interoperability test capability
In the first CAN FD plug-fest, Bosch, Peak, and Vector demonstrated the interoperability of their CAN FD implementations using off-the-shelf physical layer CAN transceivers from NXP. CAN is a common network protocol in automotive designs but has different specifications and timings for automation.
The FPGAs implementing the CAN FD data link layer as submitted for international standardization were tested using different network topologies and transmission speeds. All nodes used a 40-MHz clock frequency, an arbitration bit-rate of 500 kbit/s sampled at 80 percent and a data-phase bit-rate of 4 Mbit/s sampled at 60 percent.
The tests were performed with different busloads up to 100 percent on three nodes in bus (9 m) and passive star topologies (2 x 3 m and 1 x 6 m). The passive star was terminated with 60 Ohm at the center point.
The CiA working group specifying CAN FD device and system design recommendations proposes a ratio of 1:8 for arbitration/data-phase speed. In addition, the group will recommend bit-timings for different topologies as well as configuration registers for the CAN FD protocol controllers. CAN FD implementations should be clocked by 80, 40, or 20 MHz in order to minimize timing problems.
The next CAN FD plug-fest will take place in September and CiA plans a permanent CAN FD test environment for interoperability tests. Parties interested in participation may contact CiA office at www.can-cia.org.
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