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So I'm using LPD8806 leds with RasPi, and we are using many many lights and need multiple power sources.

With one power source, we wired the negative of the power source to a ground pin on the Pi.

It seems to work. I'm just not sure how to wire the multiple power supplies needed for all the lights. Does a ground in each power supply have to go to a different ground pin on the Pi?

Edit from comment:

The power supply has AC in and DV out, V- and V+. The LED has a ground, 5v, clock, and data. Clock and data from the Pi are sent to the strip. Then 5v and Grnd from the power supply are sent to the strip. Then a ground pin from the Pi is sent to the V- on the power supply. It works. I'm just slightly confused about what to do with multiple power supplies. Ground pin from Pi to ground of each power supply?

Do I even have the ground hooked up right (from power supply to strip, and from pi to supply) for one power supply? Because it does seem to work. Though now I'm skeptical it's right.

  • Ground is ground. All the Pi grounds are connected together. It's just a matter of convenience that more than one is available on the expansion header. Use one or more. – joan Mar 26 '15 at 21:26
  • Thanks. Does that mean run a ground from each of the power supplies to a ground pin on the Pi? – MikeHelland Mar 26 '15 at 21:32
  • You need to connect the grounds of any devices you communicate with via the gpios or power from the Pi. So the signal or current has a circuit. This isn't really a Raspberry Pi specific question. – joan Mar 26 '15 at 21:45
  • Hmm, maybe it's not. The power supply has AC in and DV out, V- and V+. The LED has a ground, 5v, clock, and data. Clock and data from the Pi are sent to the strip. Then 5v and Grnd from the power supply are sent to the strip. Then a ground pin from the Pi is sent to the V- on the power supply. It works. I'm just slightly confused about what to do with multiple power supplies. Ground pin from Pi to ground of each power supply? – MikeHelland Mar 26 '15 at 22:00

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