Will it work with RBBB

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  • November 9, 2011 at 3:57 pm #1831
    mikejr0046
    Member

    I have a Modern Device RBBB board with RBBB poto shield and a Bub 1. The3.3 volts for logic has me confused. Newbie question. Will the above work?

    November 9, 2011 at 7:34 pm #1832
    alden
    Member

    I’m not familiar with the RBBB, but looking at the bare board and the pinouts I don’t think it would work. The grblshield won’t even plug onto it as the pinout form factors are not the same.
    http://shop.moderndevice.com/products/rbbb-pcb

    The preferred board at this point is an Uno of either the DIP chip or surface mount variety.

    November 9, 2011 at 8:31 pm #1833
    mikejr0046
    Member

    The RBBB board plugs into the Proto shield and the it seems to have the same plug in as the Uno from the top.I’m doing this backwards as you sent my board today from the E-mail I got today.

    November 10, 2011 at 6:26 am #1834
    alden
    Member

    OK. If the grblshield is plugging into the protoshield then you will need to make sure the 5v line is powered with 5v. grblshield requires the 5v for the stepper logic (Stepper motor power is provided separately from the connector on the grblshield). If the RBBB is running 3.3v logic there should still be enough voltage to drive the 5v inputs on the grblshield. The grblshield does not send any output pins to the arduino – or this would blow up the MCU chip.

    Schematics for the grblshield can be found here:
    https://github.com/synthetos/grblShield

    We also recommend using the patched hex found there, or Chamnit’s fork found here:
    https://github.com/chamnit/grbl

    If you use Chamnit’s be sure to use the edge branch

    grbl really wants to run in an atmel atmega328p, not a 168, so that’s also worth checking. It’s possible to run from a 168, but you would have to hack the code yourself to achieve compatibility with the grblshield.

    November 10, 2011 at 12:08 pm #1835
    mikejr0046
    Member

    GrblShield v1.0 uses the Arduino’s 3.3v supply for the digital logic, so it only requires motor power to be provided.
    This also means really old (serial) Arduinos that do not provide 3.3v will not work.

    This is what was confusing me,now you say 5 volt logic. The RBBB board uses a 328.The BUB USB to serial board can be set to 3.3 or 5 volt logic. Sorry for being a pest.

    November 10, 2011 at 2:51 pm #1836
    alden
    Member

    Here’s the story. grblshield v1 used 3.3v for the stepper logic but expected 5v signals from the arduino to drive the TI DRV8811 stepper chips. So a set of level conversion resistors are on v1 to drop the 5v logic signals to something friendly to the 3.3v chips.

    In v2 we drove the TI’s at 5v and took off the level conversion resistors. If you ordered recently you should have a v2. The version is labeled on the board.

    So if you have a v1 you will need to provide power on the 3.3v pin and provide 5v logic signals from the digital port (D2 – D8)
    If you have a v2 you will need to provide power on the 5v pin and provide 5v logic signals.

    Is the 328 being driven at 3.3v or 5v? If 5v there should be no issue. If its being run at 3.3v if *should* work in either the v1 or v2 case, but I have not tried that combination and can’t guarantee that it would work.

    November 10, 2011 at 3:03 pm #1837
    mikejr0046
    Member

    It’s being run on 5 volts. The grblshield was sent yesterday so it should be ok.Sorry for wasting your time but I appreciate your time. Thanks mike in MN.

    November 10, 2011 at 3:39 pm #1838
    alden
    Member

    No problem, it’s not a waste of time at all. As these questions are asked they get recorded in the forum. Have fun with your board!

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