Isolated ISA (PC/104) CAN interface schematic

I recently had to design a baseboard (assorted power supplies and connectors, mounting holes etc.) for a PC/104 computer. I've always wanted to take a stab at the ISA world and since there was enough space, I decided to take the opportunity and try making a CAN interface. The interface was designed from scratch as I couldn't find any usable reference design on the web.

The design goals were:

  • non-programmable glue logic
  • commonly available chips
  • as few chips as possible
  • isolated CAN

    • The interface works and I've decided to publish the design in case you're in a similar situation. I've tested it with PEAK CAN drivers, but since they expressly forbid using their drivers on other hardware than their own, I'm currently in the process of moving to Linux.

    The following chips are used:

  • 1x 74HC251 (glue)
  • 1x 74HC573 (glue)
  • 1x 74HC245 (glue)
  • 1x 74HC688 (glue)
  • 1x 74HC27 (glue)
  • 1x SJA1000 (CAN controller)
  • 1x PCA82C250 (CAN phy)
  • 1x ADUM1201 (isolation)

    • The interface is missing the +5V DC/DC for supplying the phy side of the CAN interface (+5V and 0V symbols on the schematic). I assumed you will use a converter of your choice.

    Note:
    My PC/104 computer (Arbor Em104-a5362) required specifying which ISA adresses should actually get decoded by the PCI-ISA bridge. Check your PC for similar requirements, or the interface will not work.

    Here is the zipped Eagle project. If you decide to use this in your own design, I would love to hear about it.

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