Control 2 x AA LED string lights from FPP

[SimoG]

Evening!

This is my first year moving off Bunnings lights with the supplied controller, and going to something centrally controlled with FPP and some of Alan's hardware (FPP on Beagleboard and DMX2-24)

In my incredible planning, I neglected to include one of the elements of an Angel prop that sits in our front window. The majority of the lighting on the prop is a single string of Bunnings lights, however I have a halo above the angel which is controlled by a manual on off switch with 2xaa batteries power supply. I am happy to convert the string to be USB controlled (with a 3V regulator) however I am not sure how to connect it to FPP. Can I use any of the GPIO ports on the Beagleboard to trigger the output? I would love the input from more more experienced here on how I can get this working, with a trip to Jaycar, or something off Amazon that can arrive quickly.

 

[Notenoughlights]

I use a whole bunch of ws2811DC-15 boards to drive my bunnings "once upon a time battery lights now converted to controller power" they each have a resistor in line with the output to limit the current as they are run directly from 5v. 18 ohms 1W (might be 2W) resistors I believe

 

[SimoG]

That makes sense. I was hoping to get away with a cheaper option though(this year has been expensive). Any other ways to get usb output into fpp? I know it is late in the year to be asking these questions. Simply forgot about the element until today.

 

[David_AVD]

What voltage are the other strings you're driving from the controller board?

 

[SimoG]

All the other strings are 31V 2 wire strings from Bunnings.

 

[Skymaster]

Yes you can use a GPIO to trigger it. I do this for my push to listen button.
You wouldn't be able to drive the string directly though, you'd need a FET or similar for switching.
Under the Channel Outputs section, go to the Other tab, and as a new row. You'll need to set it up as type GPIO, and match the appropriate pin you want to use.
Mine is driven off one of the two headers available on Alan's HE123.
Give it a channel number and then set it up in xLights. Alternatively, you could overlap the channel with the same as the existing string so it comes on together.

 

[Iain]

with a trip to Jaycar

This regulator takes 4.5-35V in and puts out 3-34V with what looks like the little screw adjustment on top.

It's a regulator though so you wouldn't be able to dim the input to it (or maybe you would, I don't know enough about that).

 

[David_AVD]

Keep in mind if you're using a controller board that swaps the polarity you'll need to add a series diode so that the regulator never sees the reversed voltage. The other potential issue is that the input to the regulator will already be 50% "dimmed" because of the way the polarity reversing works. It may or may not like that.

The simpler way with a resistor to drop the voltage avoids all of this. If we assume 50mA current draw for that 3V LED string and a 31V power supply, a 560 Ohm 2 Watt resistor with a 1N4007 diode in series should be all you need to run it from the Hanson DC controller. @SimoG I have those parts in stock.

 

[SimoG]

Keep in mind if you're using a controller board that swaps the polarity you'll need to add a series diode so that the regulator never sees the reversed voltage. The other potential issue is that the input to the regulator will already be 50% "dimmed" because of the way the polarity reversing works. It may or may not like that.

The simpler way with a resistor to drop the voltage avoids all of this. If we assume 50mA current draw for that 3V LED string and a 31V power supply, a 560 Ohm 2 Watt resistor with a 1N4007 diode in series should be all you need to run it from the Hanson DC controller. @SimoG I have those parts in stock.

You are too good! I will see you this afternoon.

Thanks all for the input, these forums really are something else!!