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Thread: Null Pixels

  1. #21
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    Default Re: Null Pixels

    Quote Originally Posted by jchuchla View Post
    It's no problem asking these questions. It's curiosity like this that breeds new creations. To keep track of what's going on you have to consider what's happening to the data stream at each step of the process.

    In vixen, the data stream for the pixels starts at the output controller module. It is configured to send a given number of channels. There is one "output" or patch point for each channel of data. each of these channels corresponds with a location in the data array. Regardless of whether there is data to go in to a channel, that channel needs to be sent. in other words, you can't have a 2nd channel without a first channel. The actual position of the data in the array is what actually defines it's address. So it doesn't matter if it's patched or not. Something must be sent for each channel.

    Secondly, in the data stream, there is no such thing as null. The data stream is an unsigned 8 bit integer array. So it is a value between 0 and 255. It will never be nothing, or null. 0 has a distinct meaning of full off, and this is the default when nothing is influencing it otherwise.

    Patching elements to channels is how you connect the stream of intentions created by effects to the output controller channels. Leaving something unpatched will have the simple effect of leaving that channel always at the default value of 0.

    When a controller adds provisions for null pixels what it does is inserts 3 extra zero values for each null pixel to the output stream before it starts copying the rest of the data from the sACN buffer to the pixel output buffer (or stream)
    Apologies for my delay, at first I was more confused and had to chew on what you said. I finally opened up the Setup Display panel and the visual helped everything click, now it makes sense to me. If I need a null pixel at the beginning of a RGB strip I would add the elements for that strip and leave the first 3 channels unpatched, which results in the first array element always being assigned zero values. [While we are on the subject, I think the terminology for 'Null Pixel' would have been better as a 'Zero Pixel'. It seems more aptly descriptive. Learning the lingo is a little challenging, what with null versus zero & Elements-both pixels and array indices. Hard not to get tripped up sometimes! ;)]

    I think if I ever find myself needing a null pixel I will go with Martin's suggestion of that pixel buffer/driver. That seems to be the best way (besides an additional controller) to handle it.

    I completely facepalmed myself with the null value statement. I know the difference between NULL and 0 and that they are not the same, I just misspoke, lol.

    Thank You jchuchla and everyone for the help! I really do appreciate it.

  2. #22
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    Default Re: Null Pixels

    This is what I made: Pixel Extender.jpg I think the PCB was from RobG?

  3. #23
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    Default Re: Null Pixels

    You might want to look at Jon's use of the pixel extenders. They keep the additional hardware located at the ends of the wire as opposed to the middle of the run. I use the drivers because that is what I latched onto. The pixel extenders really are the more elegant solution.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

  4. #24
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    Default Re: Null Pixels

    Quote Originally Posted by jchuchla View Post
    That's why the expixelstick has a 5A fuse on it and power outputs for the pixel line. The stick itself certainly doesn't need 5A. That fuse eliminates the need to fuse it otherwise.
    I use a good deal of wall warts and brick style supplies. It's not hard to find free or cheap 5 and 6A power supplies this way. I even use them outside where they're clearly not intended to be. Do they die? Yep. But surprisingly infrequently, and they are dirt cheap to begin with.
    Hey jchuchla,

    I recently picked up one of Shelby’s espixelsticks and I am looking for a power supply for it. I like the idea of using the wall wart because I’m really just playing around with it at this point. I do have a couple of questions though:

    1. If I use a 5 amp wall wart power supply feeding power to the pixel stick, how many pixels can I then output from the pixel stick without requiring additional power or injection?

    2. Where do you get the free or very cheap 5 amp wall wart power supplies from?

    Thanks!

    Ken

  5. #25
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    Default Re: Null Pixels

    goodwill or other thrift shops are great sources for miscellaneous wall warts and small power supplies.

    Each pixel takes about 60mA. the ESPixelStick itself uses about 300mA. so 5000-300 = 4700mA. 4700/60 = 78.

  6. #26
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    Default Re: Null Pixels

    Quote Originally Posted by jchuchla View Post
    goodwill or other thrift shops are great sources for miscellaneous wall warts and small power supplies.

    Each pixel takes about 60mA. the ESPixelStick itself uses about 300mA. so 5000-300 = 4700mA. 4700/60 = 78.
    Thanks

    What voltage output should I look for on the wall wart?

    Ken

  7. #27
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    Default Re: Null Pixels

    same as your pixels. 5v or 12v depending on which pixels you are using.


    2018 - Moving and going to visit my Daughter in New Zealand. Most likely I will be dark or nearly dark, Some static stuff that is simple to put up.

  8. #28
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    Default Re: Null Pixels

    Quote Originally Posted by MartinMueller2003 View Post
    same as your pixels. 5v or 12v depending on which pixels you are using.
    Well I guess that makes sense!

    Ken

  9. #29
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    Default Re: Null Pixels

    Wallwarts are notorious for not being very voltage accurate. If you are going this route, check the voltage before connecting anything and then again under load.

  10. #30
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    Default Re: Null Pixels

    Quote Originally Posted by MikeKrebs View Post
    Wallwarts are notorious for not being very voltage accurate. If you are going this route, check the voltage before connecting anything and then again under load.
    This has been my experience as well. With some of the older pixels that are sensitive to any little voltage above their specified voltage, you may run into issues there.

    Mean well has some 12v 5a waterproof supplies (LPV-60-12) I have been using that can be had around the $15 mark that are pretty durable. Not as cheap as Jon's solution, but much more stable.

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