Using CAN on Zynq

Feb 01, 2013 2 Replies
H

Hello, might not be a real FPGA question, but I hope that some of you doing not only the hardware part but also working with the Xilinx SDK. I try to use the CAN controller on e ZedBoard under Linux. I *think* that I have done the CAN_L and CAN_H routing correct to the FMC connector. Now I read and write to the CAN controller registers. It seems to be correct, if I look what I'm reading back. BUT, nothing happens at the CAN lines at the FMC connector. What am I missing? Do I need special clock settings in some other register, not CAN. Or What else has to be programmed in order to get the CAN working?



Best regards Heinz



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M

AFAIK, the Zedboard has no CAN physical layer on - how did you turn your CAN Tx and Rx into CAN_H and CAN_L?

The CAN checklist goes:

  • Have you got all the same "type" of PHY (there are high-speed, low-speed, single-wire etc. variants)
  • If high-speed, is the bus using twisted pair wiring?
  • Is the bus a sensible length ("sensible" depends on bit-rate, wire quality, and sundry other issues, so start with a small bus on the bench ~2m)
  • Is the bus terminated correctly?
  • Have you another node on the bus to acknowledge the transmissions?
  • Are all the nodes running with the same bit width and sampling point?
  • Is the bus noise-free?

Do you have any CAN analysis tools (Canalyzer for example, or a scope/logic analyser that understands the protocol)?

Cheers, Martin

martin.j.thompson@trw.com TRW Conekt - Consultancy in Engineering, Knowledge and Technology http://www.conekt.co.uk/capabilities/39-electronic-hardware
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H

Sorry I didn't check the forum for a long time. In the mean time I solved all the problems. can4linux is working now on the ZedBoard. The CAN transceivers are on an FMC board, called ISM

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Regards Heinz

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