U64 8x8LED matrix / neo pixels / each 2. show call --> all leds white

Other Hardware LEDs and Multiplexing
1

Hallo,

have been here for some time now, got a lot of tips from you - great.

Currently I'm using one/two U64 LED 8x8 matrix panels with a D1mini board in a project. I have used it several times with success.

First tests now show strange effects. To find a solution, I went back to the AdaFruit_NeoPixels - simple project for a clean starting point.

Here's the effect:
In general, the panel runs, but every second pixels.show(); call makes the whole panel shine white instead of activating the set LEDs

If I change the well-known simple-loop as follows (show command executed twice), the panel will only light up white for a very short time until the next LED set is set correctly.

void loop() {
  pixels.clear(); // Set all pixel colors to 'off'

  // The first NeoPixel in a strand is #0, second is 1, all the way up
  // to the count of pixels minus one.
  for(int i=0; i<NUMPIXELS; i++) { // For each pixel...
    
    // pixels.Color() takes RGB values, from 0,0,0 up to 255,255,255
    // Here we're using a moderately bright green color:
    pixels.setPixelColor(i, pixels.Color(0, 150, 0));
    pixels.show();   // Send the updated pixel colors to the hardware.
    pixels.show();   // Send the updated pixel colors to the hardware.

    delay(DELAYVAL); // Pause before next pass through loop
  }
}

Any tips what could be the cause?

I have:

  • tested several controllers
  • all libs updated
  • external power supply unit used
  • all soldering points revised

Does anyone know that effect?
Thanks.

Greets
Volker

PS: I know I should do this, but I haven't added the input resistance or the capacitor yet - just for your information.[/code]

2

interesting side note:

just tested with an LED strip and it worked perfectly
Maybe the matrix is defect?

Thx.
Volker

3

Fit the resistor and capacitor. If the problem is still present, tell us on this thread.

4

volkeR1:
Hallo,

have been here for some time now, got a lot of tips from you - great.

Then you know about using code tags.

5

Done (sorry)

6

volkeR1:
Done (sorry)

+1 karma

7

So how about posting all the code?

8 
pixels.show();   // Send the updated pixel colors to the hardware.
    pixels.show();   // Send the updated pixel colors to the hardware.

Why do you need two pixels.show()?

If you want to do 2 of them then try this change

pixels.setPixelColor(i, pixels.Color(0, 150, 0));
    pixels.show();   // Send the updated pixel colors to the hardware.
pixels.setPixelColor(i, pixels.Color(0, 150, 0));    
pixels.show();   // Send the updated pixel colors to the hardware.