Trying to power a single 5mm Neopixel via 3.3v Pro Micro

Development Boards Arduino
1

SUMMARY

I want to put a single https://www.sparkfun.com/products/12986 (neopixel) on my https://www.sparkfun.com/products/12587 project as a status indicator. I can’t get it to take a signal from the 3.3v Arduino Pro Micro. I tried the same code with my 5v Arduino Micro and all is well. The [Überguide says that I ought to be able to signal with 3.3v if I’m powering the neopixel with 3.7v, but that is not my experience. Any advice is appreciated.

WIRING

On the 5v board I was able to connect to D7 (with and without a 330 resistor), V5, GND, and float the data out pin to get it to work.

On the 3.3v board I’ve tried getting power from USB and the same D7 (with and without a 330 resistor), V5, GND, and float wiring but the LED stays blue.

I’ve powered the 3.3v board with a 3.7v LiPo via RAW in and D7 (with and without a 330 resistor), V5, GND, and float wiring but the LED stays blue.

I’ve powered the 3.3v board with a 3.7v LiPo via RAW in and D7 (with and without a 330 resistor), RAW, GND, and float wiring but the LED stays blue.

I’ve powered the 3.3v board with a 3.7v LiPo via VCC in and D7 (with and without a 330 resistor), V5, GND, and float wiring but the LED stays blue.

I’ve powered the 3.3v board with a 3.7v LiPo via VCC in and D7 (with and without a 330 resistor), RAW, GND, and float wiring but the LED stays blue.

CODE

#include <Adafruit_NeoPixel.h>

#define PIN            7
#define NUMPIXELS      1

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_RGB + NEO_KHZ800);
void setup() {
  Serial.begin(9600);
  pixels.begin();
  pixels.show();
  Serial.println("pixel off");
}

void loop() {
  int maxbright = 100;
  int r; int g; int b;
  for(int i=0;i<=maxbright;i+=5){
    r = maxbright-i;
    g = 0;
    b = i;
    Serial.println((String) "R:"+r+ " G:"+g+ " B:"+b);
    pixels.setPixelColor(0, pixels.Color(r,g,b));
    pixels.show();
    delay(50);
  }
}

CONCLUSION

I’ve taken the most scientific approach to this as I’m capable, but I cannot get it to work. I’m now looking for suggestions.](The Magic of NeoPixels | Adafruit NeoPixel Überguide | Adafruit Learning System)

2

There is a comment on the product page of someone else having the same problem. Might want to read them…

Check this out to get more info https://learn.adafruit.com/adafruit-neopixel-uberguide

3

codlink:
Check this out to get more info https://learn.adafruit.com/adafruit-neopixel-uberguide

I linked to that Überguide complete with umlauts in my post.

4

codlink:
There is a comment on the product page of someone else having the same problem. Might want to read them…

I’ve tried the product page that I linked to as well as https://www.sparkfun.com/products/12999 https://www.sparkfun.com/products/12877 and https://www.sparkfun.com/products/11821 but do not see any mention of someone having the same problem as me. Maybe providing a link to the comment would help. You can get a direct link to a comment from the age of the post which is just after the username. Example: https://www.sparkfun.com/products/12587 … da638b4567

Thank you!

5

Wholly Carp! I figured it out. It turns out that pins 5, 7, and all the analog pins are unable to drive the neopixel. I tried this out on 2 different 3.3v Arduino Pro Micros and got consistent result. I only had pins 7 & 4 available on my breadboard. I changed it over to pin 4 in my project and all is well.

BTW, I am not using a resistor or capacitor. I did try adding a 47uF capacitor between the power pins while it was on pin D7 and it still failed.

I hope this helps out someone in the future.