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Teaser for New String Controller

Started by corey872, December 11, 2013, 06:13:53 PM

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That gives a new meaning to micro controller!  :)


Sorry. This just means more work for me next year.
I'm going back to a few strands of incandescent icicle lights.

Long time Falcon, FPP and xLights user

Roger DeBolt

I cannot wait to get my hands on these! Very nice design! I'll need to order a bunch of extras as I will probably drop and loos a dozen of those tiny things!!!  ;)


Quote from: arw01 on December 24, 2013, 01:08:09 AM
wow, impressive size there!

Now is this a teaching project and if yes, would you mind starting at the beginning for us noobs about why each piece and what it does?

Don't know that I'm qualified to be a teacher for everything, but this particular part is meant to be a replacement [or perhaps I should say 'another option'] for the variety of "SSCs" out there.  The SSC V1 and V2 don't work terribly well. SSC V3 and V4 work, but need a 3 to 4 inch long x 1 inch diameter plastic pipe for a 'housing'.  My thought was to use the one benefit of the PIC micro controller currently in being available in a tiny 14TSSOP package and build the rest of the board using small surface mount components, too.  As the scale comes down, you get a small 'set it and forget it' controller which can be sealed with heat shrink tubing and is barely more than a lump in the wires - essentially invisible at night.


That part made sense as well to my noobness except maybe size reducing current handling capacity. I think but curious for the reason the caps and resistors are even required, because technically worded so I and we can learn.

I read the story on the v1 and some sort of reflection issue on the data line. How do you get a reflection on a data line?

Sent from my Sony Tablet S using Tapatalk 4


As far as the current carrying, don't let the size fool ya!  The V1,2,3,4 SSCs had traces about .085 inches wide x 2.6 inches long which dodge from side to side of the boards.  This controller has traces .100 inches wide x .300 inches long which run straight across the back plane of the board.  Really, either one is more than enough to handle all the current which can safely be put across Cat 5 cable, though this controller would allow room for higher current should the need arise and/or different wire is used.

Caps and resistors...I guess the best way to think of those (and keeping with the water analogy so often used for electricity) - your house has running water, but you still have an assortment of faucets, sinks, bowls, cups, glasses, etc.  The running water is fine, but sometimes you want to shut it off, or restrict its flow with a faucet, or sometimes you want to save some up in a bowl or cup.

The capacitors generally help smooth the flow of electricity making sure our chips have an even flow with no spikes or surges.  Or if a spike does come along they help short it to ground while not allowing our DC power to pass through.  Resistors generally limit current so you can apply power from a source, but not flow too much current.  If the PIC tried to send power directly to a ground it would instantly burn up as there is easily 5+ amps (5000mA) available from the Cat5 line.  The proper resistor keeps that to about 25mA which is the maximum current any pin on the PIC can handle.

As far as the 'ringing' / reflection, I guess the best way to look at that is to think about a doorway.  You can be the doorkeeper representing the PIC and people can represent the electricity.  If people arrive in an orderly fashion, knock, you let them in, close the door, everything is fine.  Everything is operating in its design specifications, people come and go in an orderly fashion and everyone is happy.

But if a mob shows up, breaks down the door and storms the room, it's suddenly way too full and a huge group of people want out.  They rush through the door you haven't even had time to close, but then some people see the room is empty and they want back in, so they rush through the door again...back and forth and you can't control them because the mob is just too big.  This is the PIC operating way above it's specifications as in the V1 and V2.  Pins which were rated for 3.3V had 5V applied, they simply couldn't control the power. 

The initial V1 'fix' suggested on DLA was to lower the resistor which put even more power on the overloaded pins and the SSCV2 brought 4 overloaded pins into play, and lowered the resistor even further.  With the 'warp drive' mod, I suggested using a different PIC pin which could support the 5V signal and an appropriately sized resistor.  These posts were deleted/banned from DLA, but the V3/V3.1 mod was then copied from that.  The copy went back to a smaller resistor reasons unknown (and unjustified).

So in short summary, the SSCs use the PIC as a switch.  On V1 and V2 the pins chosen were rated for 3.3V maximum, but 5V (what the nodes require for data signal) was applied.  The PIC was unable to control the voltage so a ringing or reflection of power on the data line was observed.



i am so glad you are here on falcon christmas working to make the best ssc we have seen.

Littleton, CO Latest releases xLights/Nutcracker Forum Facebook [url=


Quote from: corey872 on December 26, 2013, 09:10:33 AM
So in short summary, the SSCs use the PIC as a switch.  On V1 and V2 the pins chosen were rated for 3.3V maximum, but 5V (what the nodes require for data signal) was applied.  The PIC was unable to control the voltage so a ringing or reflection of power on the data line was observed.

Ah, so the dataline was getting some bleed over from inside the pic itself then in reality?  This from the excess voltage over driving transistors basically and they leak?


Roger DeBolt

Cory that was a great explanation for those of us that are "not" so technically inclined! I am really looking forward to seeing the future!


Just a quick update.  I completed the build of a prototype board and started some testing on it.  Noted some characteristics of it's operation, found a couple different parts which should work better, which led to a couple design mods, which led to a way to reduce costs a bit, which led to other design mods, some changes to allow more flexibility on the board, and so on. 

So I did a bit of 'remodeling'... now up to about 'Version 89' in my head, 'Version 16' in computer files and 'Version 2' on the actual board which should be going into the etch tank soon.  Should be getting another bag of parts from Digikey and some additional testing next week. 

Steve Gase

Thanks for the update, corey!

how much of the final "product" do you expect to be DIY for the purchaser? ...and how much preassembled?  I'm assuming that much of this will be SMD... will the SMD part of the assembly process be something that the purchaser does?  |  110K channels, 50K lights  |  Nutcracker, Falcon, DLA, HolidayCoro


That's a good question.  This is mainly SMD on the scales of TSSOP, SOT23 and 0805 sizes.  If that is all greek, lets just say most of the chips are around 1/8th inch or smaller in length.  This stuff really isn't feasible to solder unless you have a microscope at ~10-20x power... or eyes WAY better than mine.

Keep in mind all this is tentative:

The way it's planned right now, at it's very basic form, this would come as a complete, functional, pre-made board.  It would have the 7 rectangular solder pads on the back as roughly outlined in my first photo.  The end user would program the PIC through 5 touch pads, confirm it, solder on 4 wires 'pixelnet in' from the hub (Cat5 with the data wire pair and bundled + and - wires or another wire bundle of your choice), and 3 wires 'node data' out to the string, program channels and confirm all is working, then seal the driver in heat shrink tube for (theoretically) years and years of service.

If the user decides they want a more 'configurable' and or 'advanced' unit, I've made 'through hole' provisions for:

two LEDs (a power LED and a 'signal' LED which Dave has considered programming to blink different indications from the PIC), one ICSP header so you can add programming pins or sockets instead of the touch pad (if you foresee needing a LOT of firmware changes), and a 'test mode' jumper (though Dave has indicated a 'test through firmware' option could also be available).  So any/all of that in any configuration could be added by the end user.

So overall, you have many configurations depending on how you expect to use the driver:

I will most likely use it as a 'basic' driver, program firmware once, solder directly to the node string and a long Cat5 cable and seal in heat shrink forever.  Basic, bulletproof, weatherproof and it just works.

If a person wanted to add the LEDs, they may opt for clear heat shrink over black tubing.

If a person wants the ICSP socket and/or test pins at the driver, but then they are likely looking to put it back in a pipe or other type of enclosure to allow periodic access.

If a person wants a more 'mobile' solution, instead of soldering cables directly to the board, they could add the waterproof 3 pin and/or 4 pin connectors at the input/output.

The idea was to allow the maximum amount of user configuration - anything from a basic 'set it and forget it' unit attached to it's string forever, to a fully re-configurable, mobile, programmable, testable unit unit with on-board status indicator LEDs.


Steve Gase

that is fantastic.  I imagine using them in each of these ways.  |  110K channels, 50K lights  |  Nutcracker, Falcon, DLA, HolidayCoro


Nice.  I have enough new SSC's to do my house for 2014 but this is very very interesting, definitely has me thinking where else I could use those and put these up in the visible areas of the display.  :) 

Roger DeBolt

Thanks for the update Cory! Sounds like a few options. I can think of many uses for my display already! Future is looking BRIGHT at the DeBolt house!

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