Off Grid Controller Setup - First timer

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FelixD

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Jul 11, 2023
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Hi all,

This is my first pixel project, so apologies for the basic questions.

I want to create an off-grid led show that will run for around 8 hours. I plan to sequence around 8 hours (8 x 1-hour sequences) worth of music in Xlights. The show will be in an area with no wifi/internet connectivity.

- I have a 200watt/hour power station.
- I have bought a 5m 12V 60led/m SK6812 led strip.

I am yet to buy a power supply or controller as I am unsure what is most appropriate for this setup.

I would like to avoid setting up any offline LAN or wireless connections. As I will not have an internet connection, I would like to control the pixels using my laptop, or use an SD card with all the shows written on it. The least interference and power consumption, the better.
$ is also a factor. I don’t want to spend for unnecessary features, and am keen to try the DIY route.

After some research and going over the manual, I believe (but may be wrong) that the best option is to use:

- a 12v 6amp 72W power supply
- a raspberry pi with FPP
- an SD card with the xLights shows written on it
- a usb sound blaster to connect a speaker

I am hoping this is possible with a simple setup that does not break the bank, given that there are only 300 LEDs to power.

My questions are:
- is a raspberry Pi the solution, or is this setup possible by using a laptop as a controller?
- does FPP/xSchedule support the ability to skip playlists/shows?
- am I missing anything essential?

(I believe my power station will only have enough juice for about 3-4 hours with this setup. Either way, I would like to program the full 8 hours.)

Appreciate any help and advice. Very keen to dive into the deep end with this.
 
FPP running on the Pi will do what you want, without requiring the PC/laptop.

The laptop will not be able to drive the pixels directly. You could also set up an Ethernet based controller but that can get pricey. If you want to use the laptop for control, FPP can be run in a more "dumb" mode where it's not playing the sequence but just accepting data over Ethernet and driving the pixels.

You can wire the LED string to GPIO 18 (or 19) which corresponds to the first (second) WS2811 output on a PiHat. That said, because of the difference in logic voltage (5V on the pixels, 3.3V on the Pi) the connection will need to be very short.

As for power, stepping up from the battery to 240V and then back down to 5V for the Pi (and maybe 12V?) for the pixels is horribly inefficient and would seriously impact your run time. You would be much better off running a DC to DC converter in this scenario.
 
Skymaster said:
FPP running on the Pi will do what you want, without requiring the PC/laptop.

The laptop will not be able to drive the pixels directly. You could also set up an Ethernet based controller but that can get pricey. If you want to use the laptop for control, FPP can be run in a more "dumb" mode where it's not playing the sequence but just accepting data over Ethernet and driving the pixels.

You can wire the LED string to GPIO 18 (or 19) which corresponds to the first (second) WS2811 output on a PiHat. That said, because of the difference in logic voltage (5V on the pixels, 3.3V on the Pi) the connection will need to be very short.

As for power, stepping up from the battery to 240V and then back down to 5V for the Pi (and maybe 12V?) for the pixels is horribly inefficient and would seriously impact your run time. You would be much better off running a DC to DC converter in this scenario.
Click to expand...
Awesome, thanks for the help.

Sorry for the dumb question, but is the DC to DC converter is meant to replace the power supply, and if so, any recommendations?

I am looking at this PiHat https://www.hansonelectronics.com.au/product/rpi-28dplus/ alongside a PI 3B+. Just wondering if this is all compatible?
 
The Hanson board will work well for what you're trying to achieve.
I have had success with these converters - https://www.ebay.com.au/itm/224451895161 - They will take any voltage at a minimum of about 2V higher than your needed output and regulate it down. As to whether it's suitable depends on the actual battery you have access to. If it's a 12V battery, and you're using 12V pixels, you might be able to get away with no conversion at all.
 
Have you got a product link on the power supply? I’ve seen the words mean different things to different people!

But as mentioned above, if you’re running from a battery you don’t need AC in between.

It also depends what sort of a battery you have. 0% charge is usually 11.8 V, but you don’t want to go that low. You'll probably want an undervoltage relay to protect your battery from complete discharge. (Stop me if you know this!)

A DC DC converter would help keep the 12V for your lights consistent, regardless of what the battery charge is. Some (called buck converters) can only drop the voltage, some (called boost/buck converters) can raise or lower the input voltage as required. You may get away with wiring 12V straight to your lights, given you're always over 12 with a 12V battery but you may want a boost/buck converter (as Skymaster said, with a plain buck converter, the input needs to be a higher than your output. Exactly how much depends on the converter). Another reason I can think of is charging - whether it's a solar or AC battery charger, they'll both charge at 14+ volts for a drained battery, so if you want to test your lights while charging, best not to go straight from the battery to the LEDs.

And another DC DC converter (12 -> 5) for the Pi. Plus some fuses.

I'm thinking you'll end up with something like this (hope this comes out ok):

Code: 
charger -- battery -- undervoltage relay -- DCDC (12/5) -- Pi -- Injector -- Fuse -- Pixels
                                         |                          |
                                         -- DCDC (12/12) ------------
 
If you are using the hansen pi hat, you don't need to do a dc to dc step down to 5v. The hat can power the pi from 12v, so one less thing to wory about.
 
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