How to connect SPI signal for 100 meters and longer LED strip segments? In case you want to use 100 or even more meter long addressable pixel LED strip segments, it’s quite complicated to wire the signal properly.
Basic Limitations of SPI Signal
There is one basic limitation you have to think about when using addressable pixel LED strips using SPI signal. The SPI signal typically can’t be connected on a long distance (we recommend to keep the wires shorter than 1 meters). That’s why we’ve developed The Symmetrizer device. This device allows you to “symmetrize” the input signal. Thanks to that, the distance between the controller and start of the LED strip can be even 500 meters.
Number of Pixels
The limitation is not really given by our controllers, but the SPI signal. In case you use more than 1024 RGB LED pixels, the framerate of the animation might fall. It’s given by the available throughput of the SPI signal line. At 1024 RGB LED pixels you can typically keep at least 25 frames per seconds, which is important for nice smooth animation.
This framerate of course depends on the type of pixel LED strips you use.
SPI Signal Connection Scheme
Since the limitation of one output of the controller is 1024 RGB LED pixels, we have to split the addressable LED strips into groups of 1024-pixel long segments. Typical LED strip uses 60 LEDs/m, thus the length of one segment is 1024/60 = about 17 meters.
As you can see, in case we use 60 LED pixels per meter, we need to split the strip into 17 meters long segments. Since the distance between the controller and the start of the pixel LED strip is more than 17 meters, we need to use The Symmetrizer device to maintain the quality of the signal. The nice feature of the LEC3 device (or SPI Matrix) – the symmetrizer is integrated into this device. Thanks to that, you need to use only output symmetrizers at the start of each 17m LED strip segment.
The long LED pixel segments are great for huge buildings or other architectural installations. It’s a bit complicated to connect SPI signal correctly, but it’s a lot easier using LEC3 and The Symmetrizer.