Alternative for Qwiic LED Strip?

Qwiic System
1

Hi,

as I cannot get the Qwiic LED strip to run stable (long story short, its somehow interfering with the 9DOF IMU) I was wondering if someone would have an alternative suggestion how I can bring light to my setup.

Qwiic is a must, as I have no other communication options (using Micromod Single Board and the RX/TX is already in use).

I thought about:

  1. using a Qwiic trigger button with LED, but do not use the trigger function itself but only the LED. Disadvantage: only 1 color, only 1 light.
  2. using RGB Addressable CBI Led but I am unsure how to get that connected via Qwiic ?
  3. using SparkFun LED Driver Breakout - but same question, how to wire it.. ?

Any other ideas would be greatly appreciated :slight_smile:

2

Those sound viable. You could also take a look at SparkFun Qwiic Mux Breakout - 8 Channel (TCA9548A) - SparkFun Electronics which can use virtual i2c addressing that may help with the conflict

3

The Qwiic LED Strip (and some other Qwiic products) use an ATtiny for the I2C interface. It’s a slow processor, meaning it needs extra time with I2C transactions, resulting in clock stretching. Some devices don’t handle clock stretching well if they’re on the same bus, unfortunately, which I suspect is the case with your IMU. Using an I2C mux as suggested sounds like a good idea, since it will electrically isolate the Qwiic LED Strip from your IMU.

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4

Hi and thank you both;

question to @SparkFro so just to verify if I understand you right:

  1. I add a Mux and attach only the 10 LED strip there; the rest of my Qwiic devices are daisy-chained from the mainboard? Like:
    1. mainboard Qwiic > button - haptic - oled - imu..
    2. mainboard Qwiic > mux - led strip
  2. Or is it like:
    1. mainboard Qwiic > mux (line 0) - button - haptic - oled ..
    2. mainboard Qwiic > mux (line 1) - led strip

And 2nd question, would it also be possible to add LED with this:

  1. mainboad > SparkFun Qwiic GPIO
  2. and then attach to the Qwiic GPIO one of these LEDs (which one would be ideal?):
    1. SparkFun RGB LED Breakout - WS2812B
    2. SparkFun RGB Addressable CBI LED 5mm
    3. SparkFun LED Driver Breakout - LP55231
5

I would suggest the second, to ensure the Qwiic LED strip is completely isolated from the other devices.

Addressable LEDs won’t work with the Qwiic GPIO. Addressable LEDs require an alternating signal at like 800kHz, you won’t be able to achieve that with the Qwiic GPIO.

I believe this requires an I2C connection, so you can’t drive it with the Qwiic GPIO. But you could connect it to your Qwiic bus.

If you want to use the Qwiic GPIO, you need to connect a “simple” LED. If you want RGB, then something like this could work: LED - RGB Diffused Common Cathode - SparkFun Electronics

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6

Thank you, then I will try your suggested approach with the Qwiic Muxer.

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7

Hi again @SparkFro

Thank you for your suggestion.

I’ve added the Muxer and it works fine with the LED strip now.

If I have other findings, I will update this post.

Cross reference to the original IMU/Led Strip issue thread.

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