Using Raspberry Pi to drive WS2812B LEDs

Hi there, I am pretty new to controlling hardware from the GPIO pins on the Raspberry Pi,

First I will give you a little background to what I am trying to achieve:

I have a 3D Printer which is controlled via my Raspberry Pi, running a distribution of wheezy containing OctoPrint. I have the Raspberry Pi Camera module connected up and a server accessible over the internet outside of my home network so I can see my prints progressing while away from home.

I am trying to use the above quoted LEDs which I purchased here:

20 RGB LED WS2812B Individually Addressable NeoPixel DC5V Arduino & Raspberry Pi | eBay

To illuminate my print bed. I chose these LED's due to them being RGB and (as the listing stated) them being compatible with the Raspberry Pi. I have thus far been unable to make them illuminate. The only light they emit is a quick purple flash when the ground and +5V supplies are first connected to the Raspberry Pi.

I have tried to use the Hyperion package on my Raspberry Pi but again no success. I ideally wanted to be able to be able to control them via the GPIO utilities already built in to the distribution to minimise CPU load (given the nature of 3D printer host software).

If anyone can advise me in this matter that would be fantastic.

Kindest regards,

Nathan

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0 e14 Contributor over 12 years ago

OK,

I have followed this set up:

http://www.tweaking4all.com/hardware/arduino/arduino-ws2812-led/

Using the wiring diagram including the external +5v and tying both grounds together. The only thing I have omitted is the 470 ohm resister.

Here is my code:

#include <Adafruit_NeoPixel.h>

#define PIN 6

// Parameter 1 = number of pixels in strip

// Parameter 2 = Arduino pin number (most are valid)

// Parameter 3 = pixel type flags, add together as needed:

//   NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)

//   NEO_KHZ400 400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)

//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)

//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)

Adafruit_NeoPixel strip = Adafruit_NeoPixel(1, PIN, NEO_GRB + NEO_KHZ800);

// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across

// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input

// and minimize distance between Arduino and first pixel. Avoid connecting

// on a live circuit...if you must, connect GND first.

void setup() {

strip.begin();

strip.show(); // Initialize all pixels to 'off'

}

void loop() {

// Some example procedures showing how to display to the pixels:

colorWipe(strip.Color(255, 0, 0), 50); // Red

colorWipe(strip.Color(0, 255, 0), 50); // Green

colorWipe(strip.Color(0, 0, 255), 50); // Blue

// Send a theater pixel chase in...

theaterChase(strip.Color(127, 127, 127), 50); // White

theaterChase(strip.Color(127,   0,   0), 50); // Red

theaterChase(strip.Color( 0,   0, 127), 50); // Blue

rainbow(20);

rainbowCycle(20);

theaterChaseRainbow(50);

}

// Fill the dots one after the other with a color

void colorWipe(uint32_t c, uint8_t wait) {

for(uint16_t i=0; i<strip.numPixels(); i++) {

    strip.setPixelColor(i, c);

    strip.show();

    delay(wait);

}

}

void rainbow(uint8_t wait) {

uint16_t i, j;

for(j=0; j<256; j++) {

    for(i=0; i<strip.numPixels(); i++) {

      strip.setPixelColor(i, Wheel((i+j) & 255));

    }

    strip.show();

    delay(wait);

}

}

// Slightly different, this makes the rainbow equally distributed throughout

void rainbowCycle(uint8_t wait) {

uint16_t i, j;

for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel

    for(i=0; i< strip.numPixels(); i++) {

      strip.setPixelColor(i, Wheel(((i * 256 / strip.numPixels()) + j) & 255));

    }

    strip.show();

    delay(wait);

}

}

//Theatre-style crawling lights.

void theaterChase(uint32_t c, uint8_t wait) {

for (int j=0; j<10; j++) { //do 10 cycles of chasing

    for (int q=0; q < 3; q++) {

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, c);    //turn every third pixel on

      }

      strip.show();

      delay(wait);

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, 0);        //turn every third pixel off

      }

    }

}

}

//Theatre-style crawling lights with rainbow effect

void theaterChaseRainbow(uint8_t wait) {

for (int j=0; j < 256; j++) {     // cycle all 256 colors in the wheel

    for (int q=0; q < 3; q++) {

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, Wheel( (i+j) % 255));    //turn every third pixel on

      }

      strip.show();

      delay(wait);

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, 0);        //turn every third pixel off

      }

    }

}

}

// Input a value 0 to 255 to get a color value.

// The colours are a transition r - g - b - back to r.

uint32_t Wheel(byte WheelPos) {

if(WheelPos < 85) {

    return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);

}

else if(WheelPos < 170) {

    WheelPos -= 85;

    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);

}

else {

    WheelPos -= 170;

    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);

}

}

It is a slightly modified Adafruit testing sketch. The only difference I believe is in the line 12 where I have changed the number of NeoPixels to 1 instead of 60.

When the positive wire is connected and disconnected and reconnected again I get a flash of light from the LED and then nothing else.

Nathan
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0 e14 Contributor over 12 years ago

OK,

I have followed this set up:

http://www.tweaking4all.com/hardware/arduino/arduino-ws2812-led/

Using the wiring diagram including the external +5v and tying both grounds together. The only thing I have omitted is the 470 ohm resister.

Here is my code:

#include <Adafruit_NeoPixel.h>

#define PIN 6

// Parameter 1 = number of pixels in strip

// Parameter 2 = Arduino pin number (most are valid)

// Parameter 3 = pixel type flags, add together as needed:

//   NEO_KHZ800 800 KHz bitstream (most NeoPixel products w/WS2812 LEDs)

//   NEO_KHZ400 400 KHz (classic 'v1' (not v2) FLORA pixels, WS2811 drivers)

//   NEO_GRB     Pixels are wired for GRB bitstream (most NeoPixel products)

//   NEO_RGB     Pixels are wired for RGB bitstream (v1 FLORA pixels, not v2)

Adafruit_NeoPixel strip = Adafruit_NeoPixel(1, PIN, NEO_GRB + NEO_KHZ800);

// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across

// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input

// and minimize distance between Arduino and first pixel. Avoid connecting

// on a live circuit...if you must, connect GND first.

void setup() {

strip.begin();

strip.show(); // Initialize all pixels to 'off'

}

void loop() {

// Some example procedures showing how to display to the pixels:

colorWipe(strip.Color(255, 0, 0), 50); // Red

colorWipe(strip.Color(0, 255, 0), 50); // Green

colorWipe(strip.Color(0, 0, 255), 50); // Blue

// Send a theater pixel chase in...

theaterChase(strip.Color(127, 127, 127), 50); // White

theaterChase(strip.Color(127,   0,   0), 50); // Red

theaterChase(strip.Color( 0,   0, 127), 50); // Blue

rainbow(20);

rainbowCycle(20);

theaterChaseRainbow(50);

}

// Fill the dots one after the other with a color

void colorWipe(uint32_t c, uint8_t wait) {

for(uint16_t i=0; i<strip.numPixels(); i++) {

    strip.setPixelColor(i, c);

    strip.show();

    delay(wait);

}

}

void rainbow(uint8_t wait) {

uint16_t i, j;

for(j=0; j<256; j++) {

    for(i=0; i<strip.numPixels(); i++) {

      strip.setPixelColor(i, Wheel((i+j) & 255));

    }

    strip.show();

    delay(wait);

}

}

// Slightly different, this makes the rainbow equally distributed throughout

void rainbowCycle(uint8_t wait) {

uint16_t i, j;

for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel

    for(i=0; i< strip.numPixels(); i++) {

      strip.setPixelColor(i, Wheel(((i * 256 / strip.numPixels()) + j) & 255));

    }

    strip.show();

    delay(wait);

}

}

//Theatre-style crawling lights.

void theaterChase(uint32_t c, uint8_t wait) {

for (int j=0; j<10; j++) { //do 10 cycles of chasing

    for (int q=0; q < 3; q++) {

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, c);    //turn every third pixel on

      }

      strip.show();

      delay(wait);

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, 0);        //turn every third pixel off

      }

    }

}

}

//Theatre-style crawling lights with rainbow effect

void theaterChaseRainbow(uint8_t wait) {

for (int j=0; j < 256; j++) {     // cycle all 256 colors in the wheel

    for (int q=0; q < 3; q++) {

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, Wheel( (i+j) % 255));    //turn every third pixel on

      }

      strip.show();

      delay(wait);

      for (int i=0; i < strip.numPixels(); i=i+3) {

        strip.setPixelColor(i+q, 0);        //turn every third pixel off

      }

    }

}

}

// Input a value 0 to 255 to get a color value.

// The colours are a transition r - g - b - back to r.

uint32_t Wheel(byte WheelPos) {

if(WheelPos < 85) {

    return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);

}

else if(WheelPos < 170) {

    WheelPos -= 85;

    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);

}

else {

    WheelPos -= 170;

    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);

}

}

It is a slightly modified Adafruit testing sketch. The only difference I believe is in the line 12 where I have changed the number of NeoPixels to 1 instead of 60.

When the positive wire is connected and disconnected and reconnected again I get a flash of light from the LED and then nothing else.

Nathan
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0 e14 Contributor over 12 years ago in reply to e14 Contributor

sweet
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0 Robert Peter Oakes over 12 years ago in reply to e14 Contributor

You have to have the DIN pin connected to PIN 6 of the Arduino as this is the data line used to talk to the chips in the LEDs

if you connected to the wrong end of the strip it wont work even though the power is correct (So need to ceck this connection)

I can not think of anything else that would need to change, having the num LEDs set to one is not an issue
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0 Robert Peter Oakes over 12 years ago in reply to e14 Contributor

??
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0 e14 Contributor over 12 years ago in reply to Robert Peter Oakes

Yep, the DIN wire was connected to Pin 6 on the Arduino and it didnt work. :/

Nathan
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0 e14 Contributor over 12 years ago in reply to e14 Contributor

Just to update, I tried a different LED and it now works. I must have damaged the first one somehow..

Once I get my whole lighting system wired up I will post pictures of the finished product and a video.

Thank you to all of you for your input and assistance.

Nathan
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0 Robert Peter Oakes over 12 years ago in reply to e14 Contributor

If your using the actual LED chips rather than the strips, then yes they are extremely sensitive to heat from the iron, I have been building up some boards with those and had to resort to a hot air reflow set on low temp to solder them in place, anything else and I was up to over 50% failure
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0 e14 Contributor over 12 years ago in reply to Robert Peter Oakes

Wow.. That is a lot of burned out LEDs..

I have taken a picture of the crude setup I have right now at my girlfriends house. Once I get home I will have another strip of 4 soldered up and then setup on my 3D printer to illuminate the bed.

I apologise about the mess..

My setup:

My Raspberry Pi controls both an Arduino and an Opto-Isolated relay board.

The purpose of this setup is so the Raspberry Pi can control a slave Arduino which sends the data to the LEDs and also switches the contacts on both channels of the relay board. The WS2812B chip +ve and -ve leads are attached to an external 5v 2A supply to prevent power problems. The power supply is fed through the relay so that the LEDs can be turned on and off via simple shell scripts executed on the Raspberry Pi. This setup is also useful because I can reprogram the Arduino through the Ino software package on the Raspberry Pi via the command line without the need for unplugging anything. This is the exact setup that I was after (though in a crude layout right now). The second relay on the relay board will be utilised as a shell controlled On/Off switch for my printer once I get home and find some 16A wire.
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