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WS2801 strip working on Uno but not Grand Central
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WS2801 strip working on Uno but not Grand Central

by blairlc on Mon Dec 16, 2019 4:08 pm

I have a strip of WS2801 12mm LED Pixels that I want to use with a Grand Central. I have gotten the strip working with an Uno. However, when I move the wires to the same pins on the Grand Central, it does not work. Sometimes they do not turn on at all. Other times they flash red or just the first pixel turns on. I have seen all kinds of weird behavior while trying to get them to work. I have tried two LED strips and two Grand Central boards. I have read through the instructions for adapting sketches to M4, but none of it seems to apply to the example sketch or the library. Is there something else different in the hardware that can be fixed in code?

blairlc
 
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Re: WS2801 strip working on Uno but not Grand Central

by dastels on Mon Dec 16, 2019 4:10 pm

What do you have the NeoPixel strip power connected to?

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Re: WS2801 strip working on Uno but not Grand Central

by blairlc on Mon Dec 16, 2019 4:12 pm

I am using a 5V 2A power supply. The red wire is connected to the +. The blue wire is connected to the - and ground on the board. Also, it is a WS2801 strip, not NeoPixel.

blairlc
 
Posts: 3
Joined: Tue Nov 26, 2019 6:34 pm

Re: WS2801 strip working on Uno but not Grand Central

by dastels on Mon Dec 16, 2019 5:18 pm

You're powering with 5v. It works on the UNO becasue it's a 5v MCU, so the logic signals are 5v. The Grand Central is a 3.3v MCU with 3.3v logic. You need to match the signal with the power. In this case you'll want level shifters on the data and clock lines. have a look at https://learn.adafruit.com/neopixel-levelshifter. The issue and solution is the same.

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Re: WS2801 strip working on Uno but not Grand Central

by blairlc on Tue Dec 17, 2019 12:07 pm

Thank you! I didn't notice that it was different on the product page.

blairlc
 
Posts: 3
Joined: Tue Nov 26, 2019 6:34 pm

Please be positive and constructive with your questions and comments.