SSC V2 has an output problem (prev - code has a bug)

[MrChristmas2000]

I'll give that a try as well. Since I don't want to redo all my SSCs cabling I'll try a shortened distance to the first node by shortening up the pixel input wire, mabey even totally eniminating it. I'll just have to deal with the distance from the SSC to the hub on the megatree.

Thanks for your help on this.

Tom

[keitha43]

Just an update I now have 3 functioning strands working perfectly (9 to go) by shortening the distance from the ssc to the first node to 2 feet with a 3 pin connector in the mix. It may work a little longer but I am sticking with what I know works. The ssc v1 allowed the distance to be a little longer for some reason. I assumed the ssc v2 would have more power but it doesn't appear to, so it must have been something else RJ was compensating for in designing the v2. I wish he would chime in on why the ss2 needs the shorter run. I am not complaining by any means. Apparently the suggested 6' is not doable if you use the 3 pin connector so I will be making use of null nodes in the future when I outline my house.

[tbone321]

I am wondering if what you are dealing with is a soldering issue.  In order to shorten these lines you are resoldering them.  The issue may be with the wirre used for these connectors.  If it was an issue with the SSC, then everyone should be dealing with it and it seem to jut be a few and not all with the same issues. 

[RJ]

If it is truely a SSC v2 issue then I would have to ask if changing the resistor from 47 ohms to 150 ohm fixes the issue. This would give you exactly what a SSC v1 does. There is no firmware change that would effect it. If it changed based on this my only thought would be we might be seeing ringing on the data line from the increased drive but I feel that is a streght. The beta test did not show this issue but maybe the lines were just not the right lenght.

RJ

[keitha43]

If it is truely a SSC v2 issue then I would have to ask if changing the resistor from 47 ohms to 150 ohm fixes the issue.

RJ

Perhaps this is what MrChristmas2000 did to get his to work. These 3 pin connectors I just got from Ray do have a larger diameter of wire than the bundle of wire I got from Ray last year with the silver colored wiring instead of copper which I used as a leader wire. My best guess is that adding the connectors (even though I was still under the 6 foot limit by a few inches) created too much resistance. Last year I direct wired without connectors. Plus these nodes are different than my original batch from early last year as white was a "warm white" on those and these are "cool white". I now have half of my 12 strands working. If these survive the rainstorms this year I will be buying more to outline the house next year. If not I will have to try flex strips. I hope the color doesn't change again.

[MrChristmas2000]

Well I finally had some time to stop and check my pixel strings setup.

The length of my pigtail from the SSC to the first pixel is in total about 3 feet which includes the connector pair and 2 ft of 3wire flat cable.

The largest difference between V1 and V2 IMHO is that the V2 has 4 outputs paralleled together for more signal drive. I will not go into a engineering discussion here but I'm not sure that's going to accomplish the desired effect.

I got my resistors in yesterday and depending on my time I will be doing some more conversions for testing.

[Corey872]

Been following this thread for a while now and running a few tests with my V1 and V2 SSC's.  In looking at scope traces of the dataline output from both, I have not seen any evidence of any 'bug' or inconsistencies with the V2 SSC.  Though conversely, in running my tests and watching my nodes - I haven't noticed the color issues mentioned in the thread cropping up either.

In reading the latest round of posts and summing the latest reported evidence, I have a suspicion as to what is going on, but will have to run some additional tests to confirm.  If my suspicions prove true, I think the fix should be fairly simple, though may require a bit more testing to come up with something which would apply 'universally' to all configurations.

 

[mokeefe]

I wonder if RJ could create the "Test" firmware option for the V2 SSC like he has for the V1.  It might help with testing and comparison.  I know I used the V1 test firmware significantly last year while working through issues.  RJ certainly has plenty on his plate so I'd understand if he didn't have the time to do it.

-Mike

[keitha43]

Before shortening the length between the v2 ssc and the 1st node, I ran the test firmware on one of my v1 ssc's overnight to see if I could find a flacky node in a strand but all were still flashing the correct colors the next morning. So far shortening the length to the first node seems to be working for me.

[Corey872]

I've completed the additional testing I mentioned above and basically confirmed my suspicions.  Sadly, this is essentially the same issue I posted last year - but the post was deleted for being too technical.

I guess I will give it a shot again this year and strip it to the bare bones...

-->THE DATA LINE IS RINGING LIKE A BELL<--

To scratch the technical surface with basic analogies... the data is sent as square wave pulses on the data line.  The PIC generates these pulses by switching on/off.  But the current in the data line can't start and stop instantly, it take a fraction of a microsecond or two.  When the PIC shuts off, the electric current is basically running into a brick wall and it bounces back and forth a bit.  When the PIC turns on, a relatively huge amount of current rushes into the 'empty' data line.  Both of these events leave the leading edge of the square wave data fairly frazzled.  When the node can't read the square wave, it misinterprets the data.

Since the V2 SSC's move more current, they are actually more susceptible to ringing than the V1's.  I'm seeing a huge amount of ringing with the V2 data line only 24 inches long.  (got some great scope traces of it!)

So what to do about it?

The easiest thing to do is keep the data line as short as possible.  I'd recommend 12 inches or less to stay on the 'more reliable' side.

The second possibility is to use 'null nodes'...but then you're wasting fairly expensive and pretty/blinky hardware.

A third option would be to put a resistor in the data line.  I'd have to do a bit more testing here, too.  But I suspect a 47 ohm resistor down by the first node would help 'impedance match' the node/line with the SSC.  The downside is this also drops the 'signal' by a bit...but there may be some compromise between damping the ringing and lowering the signal level.

The fourth option - also may require a bit more testing - but just to see what would happen, I made a data line from 15 feet of 75ohm coax cable.  The SSC V2 is driving the string 15 feet away without missing a color.  The coax damped the ringing and actually boosted the signal a bit.

So to sum everything up, as far as I can tell, there is no SSC V2 bug.  The V2 moves more current on the data line and is generating more square wave ringing.  This is simply the result of sending high speed digital data down a plain wire.  I would keep the wire to 12" or less to minimize the ringing.  There may be other fixes available to get the length up to 15+ feet if needed, though.

Anyway, just my .02 - hope I have stayed on the non-technical side of a technical issue.

[keitha43]

All 12 of my strings seem to be operating normally now with about 2 feet between the ssc v2 and the first node with the 3 pin connector within that 2 feet.

Sent from my Thunderbolt using Tapatalk 2.

[RJ]

As I already posted this was what I expected. No need for all the heavy modding. Increasing The resistor to say 100 ohms to 150 ohm should allow you to use longer feeds again.

Sent from my Charge by Tapatalk

RJ

[mokeefe]

RJ,

Are referring to the 47 ohm resistor on the V2 board?

-Mike

As I already posted this was what I expected. No need for all the heavy modding. Increasing The resistor to say 100 ohms to 150 ohm should allow you to use longer feeds again.

Sent from my Charge by Tapatalk

RJ

[chrisatpsu]

RJ,

Are referring to the 47 ohm resistor on the V2 board?

-Mike

As I already posted this was what I expected. No need for all the heavy modding. Increasing The resistor to say 100 ohms to 150 ohm should allow you to use longer feeds again.

Sent from my Charge by Tapatalk

RJ

yes

[PJNMCT]

Loved your explanation Corey.

-Paul