Controller Area Network (CAN) and Flexible Data-Rate (CAN FD)
Developed by Bosch, CAN with Flexible Data-Rate (CAN FD) is an extension to the original CAN protocol as specified in ISO 11898-1 that responds to increased bandwidth requirements in automotive networks. CAN FD has the support of semiconductor chip manufacturers and end users alike, with Infineon, NXP, Daimler and GM among the companies behind the new standard.
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CAN FD : An Overview
A standard CAN network is limited to 1 MBit/s, with a maximum payload of 8 bytes per frame. CAN FD increases the effective data-rate by allowing longer data fields – up to 64 bytes per frame – without changing the CAN physical layer. CAN FD also retains normal CAN bus arbitration, increasing the bit-rate by switching to a shorter bit time only at the end of the arbitration process and returning to a longer bit time at the CRC Delimiter, before the receivers send their acknowledge bits. A realistic bandwidth gain of 3 to 8 times what’s possible in CAN will particularly benefit flashing applications.
When building CAN FD systems and sub-systems, the higher bit-rate demands that more information is known about the physical layer as achieving maximum bit rate will highly depend on the physical layer quality. CAN FD messages also demand a common Time Quanta and that the location of the sampling point be known. For these reasons, CAN FD systems will require more advanced troubleshooting tools.
Kvaser and CAN FD
Kvaser made an early start in CAN FD and has since implemented additional functions into its CAN FD controller logic. This can be used to provide information on how to configure the CAN bits to optimize the bit timing settings in existing CAN bus layouts and identify the maximum bit-rate for a CAN FD implementation in a given harness.
In accordance with our mission to be the leading provider of innovative and cost efficient CAN solutions, we are fully committed to supporting the CAN FD standard and aim to release CAN FD compliant interfaces and dataloggers as soon as microcontrollers and a conformance test solution for the new standard become available.
Kvaser’s CAN FD implementation passed the Bosch spec test. This test verifies the ability to run CAN FD without significant numbers of error frames or other problems on the bus.
Kvaser announced that Microchip Technology, Inc., with whom it has worked closely to test and validate its IP, is integrating Kvaser’s CAN and CAN FD IP in future controller products destined for automotive and industrial applications.
Purchasing the CAN FD IP Block
Kvaser has a strategic partnership with Synective Labs to commercialize its complete set of IP blocks for CAN FD, which are now available for FPGA and ASICs for non-strategic customers.
To get the CAN FD Implementation, please contact Synective Labs:
Andra Långgatan 48
SE-413 27 Göteborg
+46 (0)31 760 72 40
www.synective.se
CAN FD Articles and Resources
CAN FD Considerations for Different Stakeholders
Kent Lennartsson’s paper, “CAN FD Considerations for Different Stakeholders “, explains the practical implications of CAN FD for Managers, Software Developers, RT Engineers, and more. Find out what CAN FD means for you.
Comparing CAN FD with Classical CAN
Kent Lennartsson recently released a paper, “Comparing CAN FD with Classical CAN“, which looks at the differences between the CAN bus that most engineers are familiar with, and the latest innovation for this platform.
Virtual CAN FD Bus Presentation
Lars Berno Fredriksson, president of Kvaser AB and chairman of the J1939 Next Generation Task Force, has published a white paper discussing a technique for multiplexing CAN with another protocol to meet the high-speed, high data volumes required by next generation heavy duty vehicles.
Bit Timing Calculator
Kvaser has released a Bit Timing Calculator for CAN FD. Use this tool to calculate system parameters and set up a reliable CANbus.
Additional Resources:
iCC Paper: ‘CAN with Flexible Data-Rate’ by Florian Hartwich, Robert Bosch GmbH
iCC Paper: ‘How to use high bit rates in a CAN system’ by Kent Lennartsson and Jonas Olsson, Kvaser AB
More information on CAN FD from CAN in Automation.
