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RPi + Other Software Is it possible to connect two ws2812b to Raspberry pi zerow?

Discussion in 'Software Support' started by async, 5 January 2021.

  1. async

    async New Member

    Messages:
    3
    Hardware:
    RPi1/Zero
    Hi, I'm new and I hope I post this to the right section.

    I'm using a raspberry pi zero w with Hyperion.NG Alpha 9 with a ws2812b directly connected to it:

    This one works:
    LED Hardware 1:
    Type: ws281x
    RGB Byte order: GRB
    GPIO Number: 18
    DMA Channel: 5
    PWM Channel: 0

    My guess is, that I could add a second LED strip with the following settings:
    LED Hardware 2:
    Type: ws281x
    RGB Byte order: GRB
    GPIO Number: 13
    DMA Channel: 10
    PWM Channel: 1

    However, if I set it up like this, the first ledstrip starts to flicker and also the second.

    Is my thought for the second configuration somewhere wrong or can the raspberry not handle it? I assumed I can just use the second PWM channel and another DMA channel and it just works.
     
  2. NeeeeB

    NeeeeB Active Member

    Messages:
    237
    Hardware:
    RPi3, +Arduino, +nodeMCU/ESP8266
    I suspect the Pi not being able to maintain a stable data signal (on your GPIO 13 and 18) when 2 ledstrips are connected.
    Sometimes it is already tricky to maintain only one...
    You may want to use a level shifter on both your GPIO to fix the problem.
     
  3. async

    async New Member

    Messages:
    3
    Hardware:
    RPi1/Zero
    Good point, any recommendation for specific type?

    Currently I have 100Ohm resistor on the data cable for each data IO.
     
  4. NeeeeB

    NeeeeB Active Member

    Messages:
    237
    Hardware:
    RPi3, +Arduino, +nodeMCU/ESP8266
    That kind works perfectly, you'll be able to connect both data on it:
    € 1,24 5%OFF | Module de transformation de niveau logique bidirectionnel bidirectionnel bidirectionnel de manette de vitesse de niveau logique de 10 pièces
    https://a.aliexpress.com/_BSloAo
     
  5. async

    async New Member

    Messages:
    3
    Hardware:
    RPi1/Zero
    Hi,

    I read in other tutorials that they mostly use 74HC14 level shifters. But I found one similar to yours:

    https://i-item.jd.com/58736421688.html

    I currently live expat life in China, so this probably should do and also has several channels.

    It also looks like I don't need the resistor on the data line anymore when using the level shifters.
     
  6. NeeeeB

    NeeeeB Active Member

    Messages:
    237
    Hardware:
    RPi3, +Arduino, +nodeMCU/ESP8266
    Yep, that'll do.
    And resistor is no more needed.