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12 Volt detecion for Stepper-Power

2019-02-06
2019-02-07
  • Andreas Exeler

    Andreas Exeler - 2019-02-06

    Hi Robert,
    is the 12 Volt detection circuit necessary?
    I have removed the Diode on my nano in the USB 5 Volt line, the Nano does not boot without the 8 Volts on Vin.
    So ife the Dispaly is on, or i can connect the App, the 12Volt Power is also on the Stepper.
    This was my idea to detect the Power....

    Greets
    Andreas

     
    • brownrb

      brownrb - 2019-02-07

      Hi Andreas

      not really. Removing the diode on the nano may not be a solution for everyone. Personally I am a bit reticent to change physical chips/components on a board as they are easily damaged through heat and ESD.

      So the detection circuit, we did attempt this several years ago, it has been raised a number of times since 2014. but when you raised it again recently we decided to have another look at it and got to thinking again. I think I sent you two circuits of my thinking at the time and suggested A7 as a possible pin to use. Since then work on that has progressed to where it is now.

      Our very early attempts was a pure hardware attempt but what we have now is a hardware/firmware solutiuon. Now in firmware 280 with the extra components the motor will not move if stepper power is off. This has necessitated a number of circuit changes including the HER208 diode. But it can easily be left out the HER208 diode cannot and not defined in the firmware and everything works as before. The circuit is probably a little more complicated that what we discussed, and there are a number of technical reasons for this, it has evolved over a number of revisions through testing and trialling different methods.

      It is not designed to be retrofitted to older boards - hence only the new PCB's support this since 10 Jan 2019. Anything before that or stripboards are unaffected and in firmware 280 just leave the stepperpwr definition commented out.

      Regards
      Robert

       
  • Andreas Exeler

    Andreas Exeler - 2019-02-07

    Hi Robert,
    OK, yes it´s the better way to use the circuit.
    Must the Diode a HER208 (a fast recovery)? Or can i use any other one like 1n4007?
    Greets
    Andreas

     

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