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  1. #1
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    arduino nano to BOB

    I have made a pcb with DB25 connector for BOB and a print for stopping starting spindle. Software used GRBL1.1 and UGCS

    this is how the nano is connected
    Attachment 469362

    Attachment 469364

    the print with nano
    Attachment 469366

    Attachment 469368

    connections BOB
    Attachment 469370

    schematic BOB (maybe some errors ??)
    Attachment 469372

    pcb start stop with relay
    the start stop is in GRBL done with the pmw ( 0-10V) signal.
    GRBL uses pin D11 for start/stop and rpm control.
    the voltage have to be above 1 V to start the spindle. Just use S and M3 /M5
    Attachment 469374

    this is how the drivers are connected
    Attachment 469376

    Here I have to stop because I am on my limit for 8 files.

  2. #2
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    arduino nano to BOB

    here two more files with power supply steppers spindle and drivers

    Attachment 469378

    Attachment 469380

    I have attached two zipped KiCad files.

  3. #3
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    Re: arduino nano to BOB

    I checked briefly your schematics and they seems to be OK.
    You have connected some output pins of the 74HC245 together. Because of the ports won't switch at exactly at the same time, they will create short and spikes.
    Unused inputs can be connected to gnd, unused outputs should be left unconnected.

    Is everything working as designed (WAD) or do you have some issues?

    nice project!

  4. #4
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    Re: arduino nano to BOB

    You have created a second thread for these 2 extra images. It is better to post them on the previous thread or zip the images then you can post them together.

  5. #5
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    Re: arduino nano to BOB

    thank you for your remarks.
    As far as I know I do not have output pins connected together.
    I arranged the pins for the steppers in such a way that one side of the nano is on the topside and the other side on the bottom of the PCB and than choose the DB25 pins.
    See the first picture. So the arrangement is different from the "normal" arrangement. In this setup you cannot use the JST connectors on the BOB.
    Everything is working fine.

  6. #6
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    Re: arduino nano to BOB



    Check the ouput pins A4,A5,A6 and A2,A3

    Edit, these pins are on the BOB!

  7. #7
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    Re: arduino nano to BOB

    @ hfjbuis, checked the pins you mentioned. My drawing was wrong, changed it. It is all working.
    5V powersupply BOB is done by the USB voltage.

    Attachment 469708

    the bend pins are cut for soldering to the top PCB
    Attachment 469710

    this is the schematic for start/stop and rpm Just use the S and M3/M4 gcode. The rpm signal has to be above approximate 2 V to toggle the transistor.
    Attachment 469712

    modified BOB
    Attachment 469714

  8. #8
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    Re: arduino nano to BOB

    @ hfjbuis, checked the pins you mentioned. My drawing was wrong, changed it. It is all working.
    Good to hear that the design of the BOB is ok!

    I like the way you solved the lack of a spindle on/off pin on the arduino uno&nano.

    I make my double sided PCB's using the toner tranfer method. I also prefer the use of DB25 and JST-XH connectors. The angled JST-XH can by soldered on both sides. One row of the angled DB25 connector can also be soldered on both sides.

    The (old) board for my rotary table running grbl_ESP32 on a ESP32

  9. #9
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    Re: arduino nano to BOB

    You will try the HC245 if you connect outputs in parallel. Only open collector and open drain outputs can be connected the way you did and the HC245 is not open an drain chip. Besides, what is the purpose of connecting outputs together?

  10. #10
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    Re: arduino nano to BOB

    Typical propagation delay of the HC125 is 9 ns, the difference in delay between channels of the same chip will be pretty small, significantly less than this. The reason for connecting outputs (and corresponding inputs) together is to increase drive current ability. Frankly provided that they are all driven in the same direction there is highly unlikely to be enough skew between outputs for excessive currents to be a problem, Besides as this works for the OP then clearly the chip has not been fried!

  11. #11
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    Re: arduino nano to BOB

    Quote Originally Posted by JohnHaine View Post
    Typical propagation delay of the HC125 is 9 ns, the difference in delay between channels of the same chip will be pretty small, significantly less than this. The reason for connecting outputs (and corresponding inputs) together is to increase drive current ability. Frankly provided that they are all driven in the same direction there is highly unlikely to be enough skew between outputs for excessive currents to be a problem, Besides as this works for the OP then clearly the chip has not been fried!
    "It works" is not the definition of "it is right". Also, just because it is working today it doesn't mean it will work tomorrow.

  12. #12
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    Re: arduino nano to BOB

    about the BOB, this is a standard Chinese BOB. I did not make any changes. I just collected some drawings from the internet and made a drawing in KiCad.

    @hfjbuis: I made the print on the diy desktop CNC , I built. this is easier for me, width of the traces are a little bit bigger. Thank you for liking my solution for the start/stop - rpm problem in GRBL

    @ A_Camera: the pins were drawn that way (connected together) by another clever person on internet. :-) I am a retired mechanical engineer....but now I have checked it and corrected the drawing.

    have a nice day

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