Project by Brenton; GlowBit Stick 1x8 - Python and MicroPython Guide

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HI. I have a project where I need two Glowbit strips (or possible glowbit ,matrix) and I want to control the strips separately, possibly different colours, different led selections, etc. I read on the document and looked at the tutorial and wasn’t totally clear. I have both a Raspberry pi 4 and a Raspberry pi zero. On these do I use either GPIO18 or GPIO12? Can I use any other pins if I wanted to control more devices?
Thanks

Hi John,

Our Glowbit gear can be chained together just like the individual WS2812s can!

image

You’d only need one IO pin if you were to chain together modules Dout to Din

Let us know if you have any more questions :slight_smile:
-James

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Thanks. If I chain them together can I still individually address the LEDs on each of the Glowbit strips so, for example I could set the first strip to all green and the second strip to all read, then change just the colour of Leds on the second strip?

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Hi John,

That’s correct. It’d appear as one long strip so-to-speak, so you can address any of the LEDs individually

-James

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Many thanks for the quick responses. I have ordered some devices to play with.

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Furthering this discussion as i dont see anywhere else suitable. I purchased a bunch of these glowbit sticks. Using the end pads and cable in between each glowstick, i connected them up, but only the first stick worked. I am using on arduino via an esp32, the sketch set for 16 leds. No matter how i try and configure, i just cant get the daisy chaining to work. Any ideas please?

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Hi Martin, Welcome to the forum!

Could you post a photo of how you’ve got everything hooked up, with a focus on the connections between the sticks?

Could you also post the code that you’re using? Three backticks (```) either side of your code will format it properly on our forum.

We’ll take a look and hopefully get you back on track!
-James

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Please see the attached photo of 2x glowbit sticks wire together.
I previously tried this with another brand stick but could only ever get the first stick working, hence changing to the glowbit sticks. I can change the the sticks around and still only the first one works.
This is the sketch i use.

//Library needs to be included
#include "Adafruit_NeoPixel.h"
// Set the pin that is connected to the D0 on the Neopixel string
#define PIN        4
// change to the number of neopixels in your string
#define NUMPIXELS 16// 
// see Adafruit strandtest example for more information on possible values.
//sets up an Object called "pixels" that our instructions will be sent to
Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);



void setup() {
  Serial.begin(9600);
  Serial.println("NeoPixel_MultiColourFadeInOutTwinklev1");
  //This line starts by initialising "pixels"
  pixels.begin(); // INITIALIZE NeoPixel strip object (REQUIRED)

  
  //now set various values starting at 0 to 15 for a 16 pixel string
  //Used as a test to make sure connection is correct.
  pixels.setPixelColor(0, pixels.Color(0, 50, 0));//green
  pixels.setPixelColor(1, pixels.Color(50, 0, 0)); //red
  pixels.setPixelColor(2, pixels.Color(15, 50, 50)); //Blue
  pixels.setPixelColor(3, pixels.Color(50, 50, 25)); //yellow
  pixels.setPixelColor(4, pixels.Color(100, 100, 100));//white
  pixels.setPixelColor(5, pixels.Color(50, 0, 50));//purple
  pixels.setPixelColor(6, pixels.Color(50, 25, 25)); //pink
  pixels.setPixelColor(7, pixels.Color(255, 255, 255)); //bright white
  //Nothing changes until this line is sent
  pixels.show();   // Send the updated pixel colors to the hardware.
  delay(3000);//wait 3 seconds before starting the show

  //prepare for system
  pixels.clear(); // Set all pixel colors to 'off'
  pixels.show();
}

unsigned long myNeoTimers[16];//array that holds millis() timer info for each neopixel
//Multi dimensional Array to hold all the data for the system
//see http://www.digitaltown.co.uk/lesson11Arrays.php for tutorial
//[lightState][lightDir][R][G][B],
//[lightState] 0-255 0 = off, 255 fully lit; controls the current brightness state...increasing or decreasing
//[lightDir] 0 = decreasing, 1 = increasing tells system if the light is increasing or decreasing
//[R][G][B] = the target RGB state
int myNeoSettings[16][5];

//const variables to make the code more readable when dealing with the array
const int lightState = 0;
const int lightDir = 1;
const int myRed = 2;
const int myGreen = 3;
const int myBlue = 4;

void loop() {
  int q;
  for (q = 0; q <8; q++) {
    if (millis() > myNeoTimers[q]) {
      if(myNeoSettings[q][0] < 0){//light is out so ready to start a new cycle
        
        //first select a colour for this neopixel
        
        //this gives a white/yellow/blue effect
        //add extra case statements and increase random max to add more fixed colours
        switch(random(4)){
            case 1://Yellow
              myNeoSettings[q][myRed] = 50;
              myNeoSettings[q][myGreen] = 50; 
              myNeoSettings[q][myBlue] = 25;
              break;
            case 2://Blue
              myNeoSettings[q][myRed] = 15;
              myNeoSettings[q][myGreen] = 50; 
              myNeoSettings[q][myBlue] = 50;
              break;
            case 3://Pink
              myNeoSettings[q][myRed] = 50;
              myNeoSettings[q][myGreen] = 25; 
              myNeoSettings[q][myBlue] = 25;
              break;
            default://white
              myNeoSettings[q][myRed] = 100;
              myNeoSettings[q][myGreen] = 100; 
              myNeoSettings[q][myBlue] = 100;
              break;
           }
           
          
          //This will select random colours
          /*
          myNeoSettings[q][myRed] = random(256);
          myNeoSettings[q][myGreen] = random(256); 
          myNeoSettings[q][myBlue] = random(256);
          */

           
           myNeoSettings[q][lightDir] = 1;//as light is out we want it to increase in brightness
           myNeoSettings[q][lightState] = 1;//give the light a brightness value
      }
      if(myNeoSettings[q][0] == 256){//light maxxed so needs to start to turn off
        myNeoSettings[q][lightDir] = 0; //tell system this pixel will be getting dimmer 
        myNeoSettings[q][lightState] = 255;//give the light a brightness value
      }
        
      //this section deals with setting the led brightness value and resetting the millis timer
      
      //get the correct values for the RGB and set the neopixel to is.
      pixels.setPixelColor(q, colourState(myNeoSettings[q][myRed],myNeoSettings[q][lightState]), colourState(myNeoSettings[q][myGreen],myNeoSettings[q][lightState]), colourState(myNeoSettings[q][myBlue],myNeoSettings[q][lightState]));
      pixels.show();
      //increase or decrease the lightState depending if getting brighte or dimmer.
      if(myNeoSettings[q][lightDir] > 0){//getting brighter
        myNeoSettings[q][lightState]++;  
      }else{//dimming
        myNeoSettings[q][lightState]--;  
      }
      if(myNeoSettings[q][lightState] < 0 || myNeoSettings[q][lightState] > 255){
        //at max state so longer value
        myNeoTimers[q] = millis() + random(200, 1500);//0.2 - 4 seconds
      }else{//increasing or decreasing in value so short value
        myNeoTimers[q] = millis() + random(20);//0 - 20 milliseconds  
      }
    }
  }
}
//this function works out what the individual RGB values should be depending on what stage it is in dimming/lighting
int colourState(int pixelMax,int pixelBrightness){
  int returnBrightness;
  //to keep values positive
  returnBrightness = pixelMax * 100;
  //because the value is stored as an int anything beynd the decimal point will be automatically removed.
  //see http://www.digitaltown.co.uk/lesson6bitsandbytes.php for more info.
  returnBrightness = (returnBrightness/255) * pixelBrightness;
  returnBrightness = returnBrightness/100;
  return returnBrightness;
}
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Hi @Martin203062 - it looks like your loops are stopping at 8, eg the first for-loop in your main loop() is defined as follows and contains the “magic-number” 8:

for (q = 0; q <8; q++) {
// your loop code...
}

This will only set colours for the first 8 LEDs in the strip, no matter how long the strip is.

Perhaps try changing it to the following, where NUM_PIXELS has already been defined as 16

for (q = 0; q < NUMPIXELS ; q++) {
// your loop code...
}

Now, no matter how long your strip is defined, the loop will always set every LED.

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Thanks Michael, i will try that.

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I can confirm that change worked, thankyou for your help!

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@Martin203062 It’s alive! :partying_face:
Happy making!

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@johnr As a second style of response to your initial question, you should be able to control separate Glowbit sticks if you initialise them as

stick1 = glowbit.stick()
stick2 =glowbit.stick(pin = 19) 

This should make stick1 and stick2 separately controllable, given that you connect the Din pin for stick1 to GPIO18 and stick2 to GPIO19. Then just issue appropriate commands to stick1 and/or stick2 appropriately.

This is the background plan for a project I am building, where there will be Glowbit sticks on 18, a neopixel string on 19 and some 3watt RGB Leds (neopixel style) on 20 …

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ArrrgH!
And trying that code style doesnt seem to work …
with the second line commented out - stick1 works :grinning:

import glowbit

stick1 = glowbit.stick()
# stick2 = glowbit.stick(pin = 19) 

but with both lines active

import glowbit

stick1 = glowbit.stick()
stick2 = glowbit.stick(pin = 19) 

stick1 fails to operate :frowning: - but stick2 works fine … :wink:

There seems to be something within the glowbit library that allows the ‘creation’ of only one glowbit object at a time.
Note: trying this sort of in isolation as i only have one off stick connected to pin18

Any one got some guidance ?? Otherwise I am in for a bunch of fuggly programming to keep Sticks and neopixel string logically separated

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Hi Murray,

Which platform are you using the GlowBIt library on? On the Raspberry Pi Pico the data signals are generated with a PIO state machine and only one GlowBit object can use a given state machine.

Thankfully the Pico contains 8 state machines, the “sm=” keyword argument can be used to specify which state machine to use, with number 0 being used by default.

Try:

stick1 = glowbit.stick()
stick2 = glowbit.stick(pin = 19, sm=1) 
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AHAH!
And the solution appears to be setting the Pico statemachine number into the initialisation call

import glowbit

stick1 = glowbit.stick()                # uses default pin=18, sm=0
stick2 = glowbit.stick(pin=19, sm=1)    # use another pin and state machine !!!

stick1 runs as expected :grinning: ,and waiting for additional sticks etc to finally ‘prove’ the code. :crossed_fingers:

Sorta makes sense when you think about what one is expecting the Pico to do …

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Hi @Brenton - thanks, I think we collided with our answers. The penny dropped when I looked into the glowbit.py library and saw the default sm=0 parameter

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