nateolson
Posts: 4
Joined: Thu Feb 14, 2019 2:29 am

Can't control LED strip?

Thu Feb 14, 2019 2:37 am

I am using the Raspberry Pi 3B with an LPD8806 LED strip wired as follows:

Pi Pin 19 = Data in of LED strip
Pi Pin 23 = Clock in of LED strip
The GND and +5V are wired properly into an adapter. The GND is also wired to Pi Pin 6 (ground) (I know that the adapter works because it is powering the pi as well).

When I turn on the pi (and thus the LED strip), two LEDs light up somewhere in the middle - one pinkish-purple and the other a light orange (right next to each other). I cannot control it, and I am trying to use lightshowpi (lightshowpi.org). I have run all the test programs I can find.

How can I control the strip?

texy
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Re: Can't control LED strip?

Fri Feb 15, 2019 3:11 pm

Hi,
we assume you have enough current to draw all the LED's - how long is the strip, how many LED's, what is the rating of the +5V PSU?
Are you driving the LED's from the same rail as you are powering the Pi (bad practice :o )
Texy
Various male/female 40- and 26-way GPIO header for sale here ( IDEAL FOR YOUR PiZero ):
https://www.raspberrypi.org/forums/viewtopic.php?f=93&t=147682#p971555

nateolson
Posts: 4
Joined: Thu Feb 14, 2019 2:29 am

Re: Can't control LED strip?

Fri Feb 15, 2019 3:56 pm

texy wrote:
Fri Feb 15, 2019 3:11 pm
Hi,
we assume you have enough current to draw all the LED's - how long is the strip, how many LED's, what is the rating of the +5V PSU?
Are you driving the LED's from the same rail as you are powering the Pi (bad practice :o )
Texy
I will check the amperage of my adapter, the strip is 60LEDs and what do you mean by rating? Amps? Wattage?

I don't know what you mean by rail, but I have an adapter with two wires running from the positive terminal - one to the pi and one to the LED strip. Same with the ground.
Thank you for your response!

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rpdom
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Re: Can't control LED strip?

Fri Feb 15, 2019 6:35 pm

nateolson wrote:
Fri Feb 15, 2019 3:56 pm
I will check the amperage of my adapter, the strip is 60LEDs and what do you mean by rating? Amps? Wattage?
Either will do. We can work it out from that and the voltage.
I don't know what you mean by rail, but I have an adapter with two wires running from the positive terminal - one to the pi and one to the LED strip. Same with the ground.
Yes, that is using the same rail (connection). You might need to use another power supply to drive the LED strip.

nateolson
Posts: 4
Joined: Thu Feb 14, 2019 2:29 am

Re: Can't control LED strip?

Mon Feb 18, 2019 1:39 am

rpdom wrote:
Fri Feb 15, 2019 6:35 pm
nateolson wrote:
Fri Feb 15, 2019 3:56 pm
I will check the amperage of my adapter, the strip is 60LEDs and what do you mean by rating? Amps? Wattage?
Either will do. We can work it out from that and the voltage.
I don't know what you mean by rail, but I have an adapter with two wires running from the positive terminal - one to the pi and one to the LED strip. Same with the ground.
Yes, that is using the same rail (connection). You might need to use another power supply to drive the LED strip.
The adapter provides .8A (800 mA), and from what I've read, each LED can pull a maximum of 60 milliamps, so I should be able to power about 13 at full intensity. I am now using a separate power supply to drive LEDs (5v .8A) and the default power supply that came with the pi to power the pi itself. I tested to be sure that the LED strip is actually being powered and it is, so the problem is with the clock in or the data in (pins 19 and 23 respectively on the pi). I don't know how to test the GPIO pins or fix the issue though. :/
Any help would be much appreciated, thank you!

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