Controlling individual LEDs on Neopixel Ring with Potentiometer

abmodelmaking · July 14, 2022, 12:06am

Hi there!

I'm using a potentiometer to turn on LEDs in sequence on a Neopixel Ring.

Everything is going well except when I try to assign individual colour values to the LEDs.
When I do this, they do change to the correct colour, but when the potentiometer is changed and the LEDs switch on or off one by one, all the 'off' LEDs flicker on for a millisecond.

Here's the set-up:

#include <Adafruit_NeoPixel.h>
#define PIN 3
Adafruit_NeoPixel strip = Adafruit_NeoPixel(12, PIN, NEO_GRB + NEO_KHZ800);

int potPin = 2;
int val = 0;
int colorVal = 0;
int reading = 0;
int x;
int prevVal = 0;
int switchPin = 6;
boolean lastBtn = LOW;
boolean NeopixelColor = false;
boolean lastButton = LOW;


void setup() {
  // put your setup code here, to run once:
  strip.begin();
  strip.show();
  pinMode(switchPin, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  reading = analogRead(potPin);
  val = (reading/1024.0) * 13;
  colorVal = (reading/1024.0) * 255;
  
  if (digitalRead(switchPin) == HIGH && lastButton == LOW)
  {
    delay(250); // Account for contact debounce
    NeopixelColor = !NeopixelColor;
    
  }
  
  if (NeopixelColor == true)
  {
    // Neopixel LED number code
    strip.setBrightness(10);
    if (val != prevVal)
    {
      for ( x = 0; x < val; x++) 
      {
      strip.setPixelColor(x,255,0,255);
      strip.setPixelColor(1,colorVal,0,255,255);
      strip.setPixelColor(2,colorVal,0,0,255);
      strip.setPixelColor(3,colorVal,255,0,255);
      strip.setPixelColor(4,colorVal,0,255,255);
      strip.setPixelColor(5,colorVal,0,255,255);
      strip.setPixelColor(6,colorVal,0,255,255);
      strip.setPixelColor(7,colorVal,0,0,255);
      strip.setPixelColor(8,colorVal,0,255,255);
      strip.setPixelColor(9,colorVal,0,255,255);
      strip.setPixelColor(10,colorVal,0,0,0);
      strip.setPixelColor(11,colorVal,0,0,0);
      strip.setPixelColor(12,colorVal,0,0,0);
      }
      for (x=val; x<13; x++) 
      { 
        strip.setPixelColor(x,0,0,0);
        strip.show();
      }
      prevVal = val;
    }
    else
    {
      strip.show();
    }
    
  }
  else
  {
    // Neopixel Color code
    for (x=255; x < prevVal; x++)
    {
      strip.setPixelColor(x,colorVal,0,0-colorVal);
      strip.show();
    }
  }
}

I really hope someone can help- it's driving me mad!
(Ignore the switch nonsense, it's leftover from a previous project.)

anon57585045 · July 14, 2022, 1:23am

Wait. Is this still a compilable, working sketch?

If it contains a lot of irrelevant details, please remove them yourself before posting because it will take us much longer to figure out what to "ignore".

abmodelmaking · July 14, 2022, 6:05am

It compiles and works with or without the switch included in the circuit.

This bit is the problem:

      for ( x = 0; x < val; x++) 
      {
      strip.setPixelColor(x,255,0,255);
      strip.setPixelColor(1,colorVal,0,255,255);
      strip.setPixelColor(2,colorVal,0,0,255);
      strip.setPixelColor(3,colorVal,255,0,255);
      strip.setPixelColor(4,colorVal,0,255,255);
      strip.setPixelColor(5,colorVal,0,255,255);
      strip.setPixelColor(6,colorVal,0,255,255);
      strip.setPixelColor(7,colorVal,0,0,255);
      strip.setPixelColor(8,colorVal,0,255,255);
      strip.setPixelColor(9,colorVal,0,255,255);
      strip.setPixelColor(10,colorVal,0,0,0);
      strip.setPixelColor(11,colorVal,0,0,0);
      strip.setPixelColor(12,colorVal,0,0,0);
      }
      for (x=val; x<13; x++)

Originally I only had 1 colour value. Introducing 12 more has caused the flickering in the video below when the LEDs turn on or off.

Diagram for reference.

abmodelmaking · July 14, 2022, 6:50am

This is what it looks like when the code is simply:

      for ( x = 0; x < val; x++) 
      {
      strip.setPixelColor(x,255,0,255);
      }
      for (x=val; x<13; x++)

Here is a video of that working:

b707 · July 14, 2022, 7:43am

can you explain the meaning of this line?

method setPixelColor in general has two parameters - the first is pixel number and the second is color. Color may be represent as 3 rgb values - red green blue. So the setPixelColor can accept 4 parameters, but you putted five in it.

What are you trying to achieve?

b707 · July 14, 2022, 7:57am

In order to sequentially change colors using a potentiometer, it is best to transform color values from RGB to HSV scale and gradually increment HUE component.
But what are you doing in the code - is absolutely senseless.

abmodelmaking · July 14, 2022, 8:00am

I'm trying to get each of the LEDs to have its own individual, constant colour when it turns on. A rainbow, if you please.
At the moment, when the LEDs turn on incrementally, all the other LEDs blink at the same time.

As for that code:

strip.setPixelColor(7,colorVal,0,0,255);

I 'borrowed' that from somebody else. I should add that this is my second project, I am a newcomer to arduino.

I may have to leave it as is because I don't understand changing from RGB to HSV.

b707 · July 14, 2022, 8:07am

we all do not understand something at first, but then we can learn.

alto777 · July 14, 2022, 1:21pm

Whatever else is causing trouble, the above might also. There is no need to strip.show() within the loop.

Set all you pixel values, then do once strip.show().

    for (x=val; x<13; x++) 
    { 
         strip.setPixelColor(x,0,0,0);
    }

    strip.show();

HTH

a7

abmodelmaking · July 14, 2022, 1:39pm

A thousand thanks!

That worked perfectly, problem solved!

abmodelmaking · July 23, 2022, 11:26pm

Encountered my next problem:

I am running 2 neopixel rings but I need the lights to turn on in opposite directions.

At the moment, when the potentiometer is turned, both rings light up anti-clockwise.

I would like one turning clockwise and the other anti-clockwise.

#include <Adafruit_NeoPixel.h>
#define PIN 3
Adafruit_NeoPixel stripA = Adafruit_NeoPixel(12, PIN, NEO_GRB + NEO_KHZ800);
#define PIN 4
Adafruit_NeoPixel stripB = Adafruit_NeoPixel(12, PIN, NEO_GRB + NEO_KHZ800);

int potPinA = 2;
int val = 0;
int colorVal = 0;
int reading = 0;
int x;
int y;
int prevVal = 0;
int switchPin = 6;
boolean lastBtn = LOW;
boolean NeopixelColor = false;
boolean lastButton = LOW;


void setup() {
  // put your setup code here, to run once:
  stripA.begin();
  stripB.begin();
  stripA.show();
  stripB.show();
  pinMode(switchPin, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  reading = analogRead(potPinA);
  val = (reading/1075.0) * 13;
  colorVal = (reading/1024.0) * 255;
  
  if (digitalRead(switchPin) == HIGH && lastButton == LOW)
  {
    delay(250); // Account for contact debounce
    NeopixelColor = !NeopixelColor;
    
  }
  
  if (NeopixelColor == true)
  {
    // Neopixel LED number code
    stripA.setBrightness(20);
    stripB.setBrightness(20);
    if (val != prevVal)
    {
      for (x = 0; x < stripA.numPixels(); x++)
       for (x = 0; x < stripB.numPixels(); x++)
   
        
      {
      stripA.setPixelColor(x,33,10,119);
      stripA.setPixelColor(1,colorVal,43,165,97);
      stripA.setPixelColor(2,colorVal,55,179,193);
      stripA.setPixelColor(3,colorVal,110,212,225);
      stripA.setPixelColor(4,colorVal,101,211,246);
      stripA.setPixelColor(5,colorVal,68,150,254);
      stripA.setPixelColor(6,colorVal,86,44,249);
      stripA.setPixelColor(7,colorVal,208,61,252);
      stripA.setPixelColor(8,colorVal,212,3,253);
      stripA.setPixelColor(9,colorVal,190,4,234);
      stripA.setPixelColor(10,colorVal,190,4,234);
      stripA.setPixelColor(11,colorVal,0,0,255);
      stripA.setPixelColor(12,colorVal,0,0,0);
      stripB.setPixelColor(0,33,10,119);
      stripB.setPixelColor(11,colorVal,0,255,0);
      stripB.setPixelColor(10,colorVal,55,179,193);
      stripB.setPixelColor(9,colorVal,110,212,225);
      stripB.setPixelColor(8,colorVal,101,211,246);
      stripB.setPixelColor(7,colorVal,68,150,254);
      stripB.setPixelColor(6,colorVal,86,44,249);
      stripB.setPixelColor(5,colorVal,208,61,252);
      stripB.setPixelColor(4,colorVal,212,3,253);
      stripB.setPixelColor(3,colorVal,190,4,234);
      stripB.setPixelColor(2,colorVal,190,4,234);
      stripB.setPixelColor(1,colorVal,0,0,255);
      stripB.setPixelColor(1,colorVal,0,0,0);
      stripB.setPixelColor(0,colorVal,0,0,0);
      
     
      }
      for ( x=val; x<13; x++) 
      { 
        stripA.setPixelColor(x,0,0,0);
        stripB.setPixelColor(x,0,0,0);
      }
      stripA.show();
      stripB.show();
      
      prevVal = val;
    }
    else
    {
      stripA.show();
      stripB.show();
    }
    
  }
  else
  {
    // Neopixel Color code
    for (x=255; x < prevVal; x++)
    {
      stripA.setPixelColor(x,colorVal,0,0-colorVal);
      stripB.setPixelColor(x,colorVal,0,0-colorVal);
      stripA.show();
      stripB.show();
    }
  }
}

I know it is something to do with this, but changing the values to negative has not effect.

 for (x = 0; x < stripA.numPixels(); x++)
       for (x = 0; x < stripB.numPixels(); x++)

I have tried the solution below with no success.

for (x = 0; x < stripA.numPixels(); x++)
       for (x >= 0; x > stripB.numPixels(); x--)

UKHeliBob · July 24, 2022, 7:14am

      for ( x=val; x<13; x++) 
      { 
        stripA.setPixelColor(x,0,0,0);
        stripB.setPixelColor(12 - x,0,0,0);
      }

system · January 20, 2023, 7:15am

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Controlling individual LEDs on Neopixel Ring with Potentiometer

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