Driving an addressable LED matrix as a display

Question

I'm spec'ing out a project to use a grid of addressable LED strips to build a pixel fireplace installation, and I'm working on how best to drive the fire graphics. I see there are python libraries for driving individual LEDs, so option 1 is simply writing some python to generate the graphics in a matrix of RGB values, and drive the LEDs.

However, there's already a really nice looking pixel fireplace simulator done here. https://hammertail.itch.io/pixel-fireplace. Is there a library that would let me map a grid of LEDs as a second display. Then I could tell the RPi to run the Pixel Fireplace program and output to display 2 that just happens to be 40x40 pixels?

I've seen packages that allow the mapping to play a given video file, but I haven't been able to find anything yet that maps as a live display.

Answer 1

Option 2 is to write a framebuffer kernel driver which sends the memory content to the LED matrix instead of HDMI / LCD. Python would be out of the question as you need to produce a .ko file which will be loaded into the Linux kernel. A prominent example of this approach is vesafb module in mainline Linux. Applications can use the framebuffer device directly, but often do so either via a library (e.g. SDL) or via the X window system.

Option 3 is to write an Xorg DRM library. This avoids dealing with the kernel, but still requires building a .so library file (AFAIK you could use Python code with C bindings, but writing it in C/C++ would be easier). You'll have to run the actual application via X windows system. An example of such library is xf86-video-fbturbo, which happens to use an existing kernel framebuffer device (and is often confusingly referred to as an Xorg framebuffer driver, while it is technically a library), but nothing prevents you from implementing Xorg graphics with a LED driver backend instead of a framebuffer.

If you're only proficient with Python, I'd stick to option 1: implement everything in Python as a userspace script which talks to the LED strip directly. With a resolution of 40x40 pixels you're unlikely to run into performance issues.

Answer 2

Assuming this isn't for a commercial solution, you might appreciate the flexibility of using something like xLights and Falcon Pi Player. You will get a fire display out of the box but you will also get a lot more should you want it. I use this approach to drive a 48x30 matrix that I can also reconfigure into 3 30x16 or a single 16x90. You may also want to consider one of the pixel driver hats (which typically give you a mosfet, fuse, and RTC).