Wiring SK9822 DotStar LEDs - Gemma M0

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spickles
 
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Wiring SK9822 DotStar LEDs - Gemma M0

Post by spickles »

I purchased some SK9822 DotStar LEDs and I'm having difficulty understanding how to wire them up in series. I purchased the LEDs and the breakout boards and proceeded to surface mount the LEDs. I really want to do some quality control at this point, and I wired up a single LED on a bread board according to the document available for the SK9822. If my memory serves me correctly the following are the pinouts:

1 - DI
2 - CI
3 - GND
4 - VCC
5 - CO
6 - DO

Realizing that there isn't much value in testing just one LED, I wired up 4. I'm ultimately going to use them in a sewing project and need to know how to make the connections. I've connected A1 and A2 pf my Gemma M0 as the DI/CI and then I connect DO and CO of one LED to the DI and CI of the next LED. So that would be in series. But with the GND and VCC being their own pins, are they wired in series (GND from one wires into the VCC of the next) or do they get wired in parallel where all GND share a common circuit and VCC all share a common circuit?

I've tried all of these combinations on my bread board and I just can't seem to get anything to light up beyond just the first LED. I really need to know for certain that I'm wiring them up properly because at this point I'm not sure if that's the issue or if I actually have a bad LED. I shouldn't have any solder bridges under the LEDs, but one never knows. Also, I was using approximately 220 degrees celsius to perform the surface mount process and I hope that doesn't burn out anything on the LED itself, like perhaps its micro-controller?

For code I'm using the code provided (below) and changing the number of pixels from 30 to 4 as that's the number of LEDs I have currently.

FULL EXAMPLE CODE: https://learn.adafruit.com/adafruit-dot ... cuitpython

I am running the latest stable version of CircuitPython 7.x and I have installed the 7.x .mpy library files.

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dastels
 
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Re: Wiring SK9822 DotStar LEDs - Gemma M0

Post by dastels »

You have the data & clock right. They go in series from one DotStar to the next. Vcc and Gnd, however, are wired in parallel: power (5v or 3.3v) goes to the Vcc of every DotStar, and ground goes to GND on every DotStar.

In the code just be sure the number of DotStars is correct as well as the data and clock pins.

Dave

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spickles
 
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Re: Wiring SK9822 DotStar LEDs - Gemma M0

Post by spickles »

Well shoot, then it sounds like I've done everything correctly and the only conclusion I can come to is that some of my surface mounted LEDs are either solder bridged or damaged during the surface mounting process. I have seen some examples where they specify the clock and data pins as 'board.MOSI' and 'board.SCK' or something like that. The example code uses 'board.A1' and 'board.A2', which I'm assuming is OK because the pins have multiple functions and alias names? I don't know which is which, but I've swapped them for sure during testing.

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dastels
 
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Re: Wiring SK9822 DotStar LEDs - Gemma M0

Post by dastels »

'board.MOSI' and 'board.SCK' will be the hardware SPI pins that are broken out on the edge/header pads. Have you tested with a prefab DotStar product? E.g. breadboarding it?

Dave

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