900 LED Infinity Mirror Programming Issue

[suddenstop]

Hi all,

So I finally got around to building my setup documented in my original post here.

900 LED (3 x 5m WS2815) infinity mirror build - planning phase questions

I am in early stages and planning a 900 LED infinity mirror table. 3 rows, each row consisting of one 5m WS2815 strip. I plan on running FastLED library to run some similar visuals that can be viewed at this link. I plan a 12V 40A supply for the lighting, 5V 3A for an Arduino Mega running the data line. A few questions come to mind. Given the amount of LEDs in the build, should the delay be a concern? I have read several other posts talking about delays down to ~20fps but with this being …

Long story short, I am now waiting for my glass to arrive and wanted to ensure the lights are running smooth. They are not. I intended to start with the some rainbow code credited to reddit user, /u/Procupine. You can see the intended final product from Procupine's build here. Imgur: The magic of the Internet

In the DropBox link below you will see my wiring setup, by flawed rainbow video results and the rainbow.ino file. Any help would be suggested to help clean this up to work work as designed.

Specs:
Lights: WS2815 (3 rows, 287 per row, 861 total)
Power supply: 12V to LED strips, 5V to board
Board: Elegoo MEGA 2560 R3 Board ATmega2560 ATMEGA16U2
FastLED Version: 3.4.0

I have properly grounded the board to the power supply. I have also tried running with a 470 Ohm resistor on the data line with even worse results. When the resistor was installed, only about 25% of my top row of lights would light up. I have also confirmed I am running the data line to Din on the strips.

Thank you all in advance.

Infinity Bar Top

Pastebin link

Rainbow - Pastebin.com

[UKHeliBob]

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[sterretje]

I think that the main problem is V_IH; that would be 0.7 * 12 = 8.4V; the Mega's output voltage is 5V maximum.
From the WS2815 datasheet

Do you have capacitors (something 1000 microFarad) at the beginning of each strip?

@suddenstop

You can see the intended final product from Procupine's build here

Same strips (WS2815)?

I ran your code on a Mega with 420 pixels (seven times one meter WS2812B strips with 60 leds each) and it looked quite OK; it went through all motions as far as I could see.

[suddenstop]

I really appreciate you looking into this to the depth that you did. The Arduino is being powered by it's own 5V supply and the WS2815 strips by their own 12V supply.

I have since solved my issue. First I neglected to use any power injection. Really just an ametuer mistake thinking that I didn't need it with the 12V strips. I was only measuring around 5V at the end of the last strip. Now I am injecting 12V power at the beginning and end of each strip. Lowest voltage measuring is now 11.8V mid strip. This also drastically reduces the current draw through the first strand as it's now shared equally.

My main issue was that I was incorrectly grounding my Arduino to the earth ground from the 12V supply and not the common 12 V- ground that is shared with the light strips.

Long story short, it is all good now!
https://photos.app.goo.gl/djTKqLtbvCwmhwH67

[Paul_B]

@sterretje

I think that the main problem is VIH; that would be 0.7 * 12 = 8.4V; the Mega's output voltage is 5V maximum.
From the WS2815 datasheet

I am pretty sure that is a total foul-up in the datasheet and they actually mean proportions of "VCC"!

VCC is the 5 V logic supply, derived from an internal shunt regulator. The obligatory capacitor is connected to it.

"100NF"?

And that is only a couple of blunders.

12V DC power supply, can effectively reduce the operating current of the pixel LED, and decrease the voltage-drop

So just how does having a 12 V power supply "reduce the operating current of the pixel LED" if there are only single LEDs, not three in series, and the excess voltage is simply wasted as heat?