Controlling CAN terminator with Propeller pin.

I'd like to be able to switch the terminator resistor on and off with a propeller CAN node programmatically instead of using using a physical jumper. I thought of using a tri-state buffer, but the bus voltage goes over the usual 5v allowed. Most of the transistor examples are switching voltage a don't seem valid for the changing voltages of a CAN bus. A physical relay also isn't preferred. There is a way, I just have found the right search terms...

Comments

  • So, what exactly are you controlling?
    Returning to Spin after two months of not coding micros at all, forgetting to use :=
  • Terminating resistor enabled or disabled.
  • Use a FET-output optocoupler, such as the TLP3545A, with pins 4 and 6 (in this case) in series with the resistor.

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Or an LDR output opto coupler (though some experimentation needed for the right resistance value) for instance NSL-32SR2
  • jmgjmg Posts: 14,109
    sccoupe wrote: »
    I'd like to be able to switch the terminator resistor on and off with a propeller CAN node programmatically instead of using using a physical jumper. I thought of using a tri-state buffer, but the bus voltage goes over the usual 5v allowed. Most of the transistor examples are switching voltage a don't seem valid for the changing voltages of a CAN bus. A physical relay also isn't preferred. There is a way, I just have found the right search terms...

    As above, if you want the full transient tolerance of CAN, some isolation is needed.
    Phil quotes a 4A SSR, but you might be ok with smaller/cheaper ones. egg CPC1006N, VO1400AEFTR , CPC1002N, TLP241A(TP1,F etc
  • Peter JakackiPeter Jakacki Posts: 8,780
    edited 2019-06-04 - 03:54:18
    I've used G3VM-61G1 optos for electronic termination selection. They are 1ohm 400ma devices but listed as EOL which is not a problem but the replacement is G3VM-61VY

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