NEO pixel on 1616

[coderatchance]

Hello all,
trying to use the "neo pixel" on ATTiny 1616. Although it works via the basic port output, for example,
cannot get it running via the open-collector NPN with a pull-up.
The strip is made with the WS2812B leds.

Here is the code:

//NEO PIXEL tiny library
#include <tinyNeoPixel.h>   // *****************************************

//pixel led or neon led ?
#define PIN_NEO_1  PIN_PA4  // Lc @ IRV5

//MY RGB
#define Red   PIN_PA3
#define Green PIN_PC0
#define Blue  PIN_PC1

#define NUMLEDS 100

// Parameter 1 = number of pixels in strip
// Parameter 2 = Arduino pin number (most are valid)
// Parameter 3 = pixel type
//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)
//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)
//   NEO_RGBW    Pixels are wired for RGBW bitstream (NeoPixel RGBW products)

tinyNeoPixel NEO_strip = tinyNeoPixel(100, PIN_NEO_1, NEO_RGB + NEO_KHZ800);

void setup() {
  
  delay(100);
  
  pinMode(Red, OUTPUT);
  pinMode(Green, OUTPUT);
  pinMode(Blue, OUTPUT);
  
  pinMode(PIN_NEO_1, OUTPUT);
  
  NEO_strip.begin();
  NEO_strip.show(); // Initialize all pixels to 'off'

}

void loop() {
  analogWrite(Red, 255);
  analogWrite(Green, 255);
  analogWrite(Blue, 0);
    
  //rainbowCycle(10); //wait 10ms
  NEO_strip.setPixelColor(1, 255, 0, 0);
  NEO_strip.setPixelColor(2, 0, 255, 0);
  NEO_strip.setPixelColor(3, 0, 0, 255);
  
  NEO_strip.show();
}

The analyser preview:

Something is going on, but wondering why the led does not want to turn on :)

hmm...

Wondering where is the signal :)

[coderatchance]

Here it is!
The problem was in the Pull-up resistor, started with the 4k7 , ended on 100 ohms , however, 150 and 180 works as well, need to read more about this pull-ups :)

The code is more or less the same as above, but the analyser output is more revealing.
Here is the pic. of the so-called rainbow, using 100 leds so impossible to actually see the analyser data in detail.

This is 500k sampling on 8MHz

We can easily look into the details, for example, the bit value of each LED :)

Indeed, this is 24 bit and it more or less depends on the led strip used. Here is basic strip considered:

More about the relevant led-strips is here

This leds are hungry! Running 100 leds on 5V will draw around 1A , however, at least 150mA will be needed to light-up 100 leds and the voltage will drop to 2.4V ... ah need to test at least the 12V ledstrip...

[grandaspanna]

Just wondering - why are you using a transistor on the output? The signal pin only has to drive the first neopixel. Each pixel then drives the next one after it. However, it is true that you need to watch the power consumption on the power pins of the pixels, but this is generally kept separate from the microcontroller. I've done plenty of projects with 100+ neopixels.

[coderatchance]

Thanks for the question, I am bound to the transistor on the output, this is the only way to get to the pin :/ anyway, what do you do if you have more than 5V ledstrip?
Do you work on 12V or 5V?
It would be interesting to know where to get more of code examples and to play around :)

[grandaspanna]

I mainly use 5V, but often use the smaller pixels (2427 & 2020, plus the sidemount SK6812) at 3.3V. If you need to level shift, then yes, you'd need something, but the current on the signal pin is very low. There are mountains of neopixel examples if you go hunting. I'm trying to remember if the WS2812FX library fits on the 1616 (I think it does, with limitations, and there was another discussion here about library compatibility), but it gives you some really nice animation effects.

What sort of final result are you looking for?

[coderatchance]

Thanks , the library WS2812FX so far works fine on 1616, at least the basic ATtiny example, however started to use other effects and so far no luck , does not want to compile... Anyway, I will stay with the Neo tiny library as provided here... have to look for the effects...

Re "final result"... so far I have "two" channels, so I am looking for effects that would leverage that, any ideas?