LED Pixel and Node Terminology

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LED Pixel and Node Terminology

When discussing individually addressable bulbs, there are many terms that can be used.  In an effort to standardize these terms when dealing with RGB devices, Light-O-Rama defines the following:


'LED' (or 'Light'):  A single locus (point) of light.  One or more LEDs are part of a NODE. LEDs (or LIGHTs) are elemental - they can NOT be broken down further.

'Node':  A single processor for one or more LEDs.  Nodes are PHYSICAL.  Think of them as the processor chip on every individual LED/LIGHT.

'Pixel': A pixel is a collection of one or more NODEs.  Pixels are VIRTUAL, and controlled by a single TRIPLET.  All nodes that are part of a pixel will react in the same way.  Pixels are the 'bridge' between the physical world and the virtual (sequencing) world.

'Triplet':  A group of 3 CHANNELs that set the color of a PIXEL.  When we speak about a triplet we do not specify the order of the CHANNELs.  For example, some pixels are in RGB order, while some others could be in GRB order.   Either of those orders refer to the same triplet.

'Channel': A channel controls a single color of a TRIPLET.  A TRIPLET consists of 3 channels:  Red, Green, Blue in the order specified by the manufacturer of the string.


The number of TRIPLETs required will always be the same as the number of PIXELs.  When we talk about something that you can physically touch we use 'Pixel'.  When we are talking about it otherwise, say in reference to a sequence, we use 'Triplet'.


Here are some examples to help:


A Light-O-Rama Cosmic Color Ribbon has 150 LEDs. Every 3 LEDs are attached to a single NODE.  When you set the resolution of the CCR, you control how many consecutive NODES are assigned to a single PIXEL.  At a resolution of 50, each NODE is controlled by 1 PIXEL for a total of 50 PIXELs.  At a resolution of 25, every two NODEs are controlled by 1 PIXEL for a total of 25.  In all cases a single TRIPLET will control a single PIXEL.


You may have a string of 170 RGB LEDs.  Each one of these LEDs is attached to a single NODE.  If you do not group any of the NODEs together, you will have 170 PIXELs that are controlled by 170 TRIPLETs which consist of 3 CHANNELs each for a total of 510 CHANNELs.



Separating the notion of Nodes from Pixels also allows virtual addressing to make more sense.  For example, say you have 30 pixels that are arranged as a 10 x 3 matrix.  When you physically construct this matrix, you will most likely use a snake pattern as that minimizes the amount of wire/etc.  Your NODES will look like this:


1  2  3  4  5  6  7  8  9  10

20 19 18 17 16 15 14 13 12 11

21 22 23 24 25 26 27 28 29 30


Notice how when we get to the right side, we don't start over at the left, but instead go one line lower and in reverse order.  While that makes a lot of sense while building the matrix, logically the pixels are not in the correct order.  Since we read left-to-right, we'd like to see all the pixels ordered from left to right.  If we were to set the 'Zig-Zag' parameter on a PixCon16 to 3, the physical nodes will still be in the same order, however the pixels will be numbered:


1  2  3  4  5  6  7  8  9  10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30


Since NODE refers to the physical and PIXEL refers to the virtual, we now can state 'Node 18 is Pixel 13', and it makes sense.