Leds are flickering. Any input as to where the problem might be? GOAL:

Matt_Wagner · August 28, 2018, 1:37pm

Leds are flickering. Any input as to where the problem might be?

GOAL: Control the mapping of a WS2812B led tape through Arduino Uno & DMX shield, using only a single channel of dmx from a small console.

Software Version: Arduino 1.8.5, FastLED 3.1.6, Conceptinetics_RDM_alpha3

Parts:
1x - Arduino Uno R3
1x - CITC-DRA-10-R2 (Dmx shield by Conceptinetics)
1x - WS2812B, one meter, 60 leds
1x - 5v 20a power supply (metered at exactly 5v)
1x - Baxter pocket console, 8 faders, patched 1:1

Additional details: The console provides the control data into the shield as dmx. The shield is set to Slave, TX-uart, & RX-uart. Only one channel of control is needed, dmx address 001. All devices have a common ground, and the tape has been tested previously both on this arduino and elsewhere. There is a 390ohm 1/4w resistor on the data line as per a suggestion in a Adafruit guide. The tape is undamaged and is functioning properly outside of this application. I have also swapped the console out for a DMXcat (City Theatrical) so that I could affect the refresh rate of the DMX. This didn’t offer a solution, but it did change the flickering rate. The FastLED library is being utilized and provides the functionality for the mapping. The effect I am trying to create is, as the fader goes up, more of the led tape fills. When channel 001 is at full (255) the led tape should be fully lit. With the fader at half, (128) the tape should be lit half way through, the other half being dark/off.

GITHUB LINK - for the Arduino sketch

github.com

Matt7k/Fast-Led-DMX-shield/blob/master/Arduino sketch

#include <FastLED.h>
#include <Conceptinetics.h>
#define NUM_LEDS 60
#define DATA_PIN 13
#define DMX_SLAVE_CHANNELS 1
CRGB leds[NUM_LEDS];
DMX_Slave dmx_slave ( DMX_SLAVE_CHANNELS );

void setup() { 
  FastLED.addLeds<WS2812, DATA_PIN>(leds, NUM_LEDS);
  dmx_slave.enable ();  
  dmx_slave.setStartAddress (1);
}

void loop() {
    int val = ( dmx_slave.getChannelValue (1)); 
    //retrieve the dmx value on channel 1 and save it to val.
    
    int numLedsToLight = map(val, 0, 255, 0, NUM_LEDS); 
    // Mapping function that translates the dmx value (0 to 255) saved in val to the number of leds that should be lit (0 to 60).

This file has been truncated. show original

VIDEO LINK - of the led tape flickering

Yves_BAZIN · August 28, 2018, 2:35pm

@Matt_Wagner
indeed your FastLed.clear() is not necessarry

could you twist the gnd file with the data file. it will shield the data from getting noise

then i n your program could you ouput the val value in the serial monitor ?

Jeremy_Spencer · August 28, 2018, 3:18pm

Try without the resistor in the data line…

John_Sullivan · August 28, 2018, 5:21pm

Check the 5V along the length of the strip… add possible 1000Mf at the power connection.

Matt_Wagner · August 28, 2018, 5:26pm

I’ve removed Fastled.clear from the sketch, and removed the resistor on the data line.

My research indicates that the dmx shield uses the serial input, so I don’t think I can view it from the computer at the same time that the sketch is running.

Yves_BAZIN · August 28, 2018, 5:29pm

@Matt_Wagner still flickering ?

Matt_Wagner · August 28, 2018, 6:12pm

I should be able to cannibalize a 1000uf capacitor from another project tonight, but on hand I have a 470uf that I just attached (obviously not while the system was energized). No luck so far. Still flickering.

Yves_BAZIN · August 28, 2018, 6:13pm

@Matt_Wagner have you tried two twist the ground and data wires ?

Matt_Wagner · August 28, 2018, 8:05pm

Like so? or should I be more aggressive and have them tightly coiled together? In the picture, black is ground, red is hot, and green is data.

What is the potential that having the usb connected from the pc could cause a problem?
missing/deleted image from Google+

Yves_BAZIN · August 28, 2018, 8:13pm

@Matt_Wagner yes but you could do more twisting even
missing/deleted image from Google+

Jeremy_Spencer · August 28, 2018, 8:24pm

I think that you said that the LEDs work fine on a different setup, I suspect that this may relate to the data timings from the DMX controller. The LEDs may not actually be WS2812Bs, they could be SK6822s or another variant. Is there any way to change the LED type on the DMX controller? Does the manufacturer provide any support?

Testi_Cuss · August 29, 2018, 1:55am

Well, what’s the purpose of the USB connection anyway? Just to power the UNO? Get rid of it and power the UNO from the same source as the LEDs. Otherwise you are risking some nasty ground-loops & SMPSU garbage interference in case the PC at the other end of the USB cable is also connected to mains… If it is a laptop then just unplug the power adapter and let it run on battery to see if it helps.

Ivan_Fominskiy · August 29, 2018, 5:54am

try to change the power supply. Or if possible try the 5 v power bank.

Matt_Wagner · August 29, 2018, 5:41pm

@Testi_Cuss I have done so but the problem remains.
@Ivan_Fominskiy No luck, problem continues.

I believe I’ve found the issue, and I think it has to do with the timing on the LED tape conflicting with the data coming in on the dmx. Not entirely sure if upgrading to an Arduino mega will help, but I’m going to try that. I also have a new dmx shield coming in soon that has isolation.

Matt_Wagner · August 29, 2018, 9:07pm

I’ll let everyone know if I find a solution. Big thank you to everyone who helped trouble shoot this problem!

Will_Tatam · September 2, 2018, 11:51am

I would add a logger statement to make sure you are always seeing the dmx value for channel 1 stay constant.

Does the flickering continue if you disconnect the dmx input.

I went though about 3 or 4 different dmx libraries before I found one that worked with my teensy without causing issue with the LEDs

Will_Tatam · September 2, 2018, 12:10pm

It might also be worth double checking which pins are in use. Some pins will work, but are not best suited