Smartmatrix - FadeCandy - Raspberry pi schematic?

#1

I’ve been playing with the SmartMatrix & Teensie for a while now. I have gotten the basics working, last night I thought I’d have a crack at the Raspberry Pi, FadeCandy, Teensy setup. I found the images in the Fadecandy/docs/images folder, which offer a block diagram (though there is no Teensy referenced) Am I missing something? I read through the different files and by the end of the night had myself completely confused. Any clarification or documentation would be most appreciated

Best
Pete Lindstrom

PS What I am attempting to do in the long run is have 12 SmartMatrix panels in a single row displying texts etc. So any thoughts or comments on that topic are welcome as well

#2

The port of Fadecandy firmware to run on SmartMatrix is hacked together and not documented well. If you’re looking in the docs folder, any docs are probably referring to the Fadecandy board which drives WS2812 LED strips and not multiplexed matrix panels like SmartMatrix.

You need this firmware running on the Teensy:

You need to use this modified server which can talk to the SmartMatrix_Fadecandy device:

Jason Coon contributed a compiled version of the server available in the bin/fcserver-rpi folder, so you shouldn’t have to compile the server.

What I am attempting to do in the long run is have 12 SmartMatrix panels in a single row displying texts etc.

Is all you want to display simple scrolling text across 12 panels, or do you want nice looking graphics and patterns behind the text as well?

#3

Okay so the FadeCandy hardware is not actually used? It is virtual in the Teensy?

#4

I suspect more than just text will eventually be displayed

#5

Okay so the FadeCandy hardware is not actually used? It is virtual in the Teensy?

Yes

#6

Thank you so much for clearing that up for me!

That being the case, I presume that the number of SmartMatrix Panels that the Teensy can address remains the same. Do you have any thoughts or hints on ways of cascading multiple Teensy / SmartMatrix groupings? i.e. two Teensy’s with six panels attached to each, with the data from #1 cascading into #2.

Again Thanks
Best
Pete

#7

You can chain up to 4x 32x32 panels to make a 32x128 or 64x64 display from one Teensy, but you’ll have to back off the framerate and color depth because of memory and CPU limitations. I find the 64x64 performance barely tolerable with slightly visible flicker. Fadecandy has it’s own overhead, and you can get about 90Hz refresh with a 32x64 display, and 64x64 either didn’t work or didn’t work well enough for me consider it acceptable.

You might want to look at this project for driving panels from a Pi directly. It can chain a lot of panels, but the color depth isn’t going to be as good as SmartMatrix_Fadecandy. It will however be much cheaper than buying a bunch of Teensy’s. The project author has an open source shield design. Note that Adafruit’s shield for this project uses an outdated pinout so I wouldn’t recommend using it.

#8

I don’t really need the depth, 16 actually fits the space well, I’ve had 7 panels in series working acceptably. Things seem to break after going beyond 256, I’m unsure if it’s a variable thing or the limits of hardware. If I go out to 8 panels things get a little weird, and don’t get any better after that. I will look into the Rpi project you recommend

I really appreciate your help, and hope I’m not being a pest asking all these questions

Pete

#9

I’m happy to help! 8x 32x32 panels is more than I’ve tried myself, though I did try 8x 16x32 panels and that worked fine, after I modified the library a bit to handle a width of 256 (was previously using an unsigned char for width I think).