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Thread: Control servos via Vixen 3 with Mini Maestro servo controller

  1. #11
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    BarnabyBear has you on the right track, you're in good hands there.

    DMX, Renard, and GenericSerial are all very similar protocols. They're all serial, they all contain a stream of bytes representing channel values. The same information can be conveyed in all 3. Their differences make each suitable for different hardware applications.
    DMX is not a standard UART based serial signaling. It uses strict timing, with a nonstandard baud rate, with pauses at certain points to signal start and end of a frame. Normal serial libraries can't deal with this easily. This is best suited for applications where you want/need to bitbang your communications. It's by far the most standard lighting protocol, and is efficient and fast and robust. But not necessarily easy for beginner to code for. You also may not be able to handle the bitbanging speed on an Arduino and still leave enough clock cycles to do anything else that you need.

    Renard uses standard UART based serial signaling. No special timing is needed. It allows for a user definable baud rate, and as many channels as you'd like to send. I don't recall the exact packet framing off hand, but it's found somewhere here on the forum. It's like DMX but is easier to work with and a bit more flexible. It has historically been slower than DMX however. Until recently, you couldn't push a standard UART baud rate above 115,200. Newer UART chipsets now allow for faster baudrates that exceed DMX's 250,000 rate.

    Generic serial contains the same variable standard baud rates and data length that the renard protocol allows, but it allows you to specify what goes in front of and behind the data block. I've never understood why this is any more practical than renard, but it seems to be popular with people coding for Arduino.

  2. #12
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    Thank you for the assurances. In that case, I will stick with the generic serial that BarnabyBear is suggesting and forget about DMX for a while. It seems like the more user friendly option.

    Sent from my Moto G (4) using Tapatalk

  3. #13
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    Take a reasonable microcontroller.
    Have 12 character input buffer that takes the serial from the computer.
    Have a 3 character output buffer.
    Have a timer you reset when your intererrupt handler for RX character occurs.

    Fill the 12 character buffer with raw serial from the computer. Detect that X amount of time has occured with no character, and begin outputting SSC type serial out. This can be with the same Serial port, since there is no need for return data on any connection. SSC has 0xff, the servo#, and 0-0xfe angle to set. You increment the second byte and copy the third from the correct spot of the input buffer.

    All this can be done with a very tiny micro.

  4. #14
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    Thank you for the suggestion, Shockwave. To be completely honest, I don't entirely understand your plan, but most of it makes sense to me. Implementing it will be another thing entirely, and I definitely don't understand how to do so. Could you give me some specific steps to follow? Any help is really appreciated, and I thank you for your patience!

    Sent from my Moto G (4) using Tapatalk

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  6. #15
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    I'm sorry, I wasn't clear enough I guess. What you need is a TRANSLATOR to change the RAW serial stream of Vixen into the SSC serial stream of the Maestro.

    ex)

    Say there are three servos, 1, 2, and 3. and they are at 0, 50 and 100%. The serial out from vixen would be three bytes; 0x00, 0x80, 0xff
    SSC on the Maestro has a start byte followed by which servo you want to control, then the rotation. For each servo. So what you'd then want on the maestro would be:

    0xff 0x00 0x00 0xff 0x01 0x80 0xff 0x02 0xff

    You need to build a hardware device to change the raw serial stream into a SSC formatted serial stream.

  7. #16
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    Quote Originally Posted by Shockwave View Post
    I'm sorry, I wasn't clear enough I guess. What you need is a TRANSLATOR to change the RAW serial stream of Vixen into the SSC serial stream of the Maestro.

    ex)

    Say there are three servos, 1, 2, and 3. and they are at 0, 50 and 100%. The serial out from vixen would be three bytes; 0x00, 0x80, 0xff
    SSC on the Maestro has a start byte followed by which servo you want to control, then the rotation. For each servo. So what you'd then want on the maestro would be:

    0xff 0x00 0x00 0xff 0x01 0x80 0xff 0x02 0xff

    You need to build a hardware device to change the raw serial stream into a SSC formatted serial stream.
    also worth noting is that the translator doesn't necessarily need to be a hardware device. If it's more up your alley, you could do it all in software. You could use the sACN output and send it right back to the same machine you're sending from. Then a custom utility app (that you'd create) could read the values in the stream from there and output it formatted however you need.

  8. #17
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    Default Re: Control servos via Vixen 3 with Mini Maestro servo controller

    Thank you for the clarification, Shockwave. That makes more sense. It sounds like using Arduino as a middleman, so to speak, between Vixen and the Maestro controller is along the same lines of what you're suggesting. If that is the case, then it might be best to continue down this route. Is there any other hardware device that I could buy that can accomplish the task of translating? I also want to look into the software option that jchuchla mentioned, but having never written software before, I'm not sure where to begin. I'm going to check myself, but is there a software/resource that you could recommend that would give me a good start? Thank you again for all the help!

    Sent from my Moto G (4) using Tapatalk

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