mapping.md

title	Mapping
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WLED now has the ability to remap your LED strip programmatically.

What is it?

This allows us to treat the WLED strip as if it is wired in any way - we can then use the mapping feature to address the strip in any order. This allows for matrix support, serpentine runs and such.

LED Maps replace and over-ride the older Gap system. Note: that if a ledmap.json file exists, the 2d-gaps.json file will be ignored.

How do we do it?

Create config file

Navigate to the edit page for your WLED device by adding /edit to its address - for example, https://my-led-device.local/edit Use this edit page to create a file called ledmap1.json, where 1 is incremented for each map you load on your controller.

Note: If the filename is ledmap.json, the config file will not load; the filename must end in a number even if there's only one config file.

Formatting

ledmap1.json file needs to be a JSON-formatted file with the key being "map" and the value being an array of numbers [0,1,2,3...] representing the new order of pixels. The position of values in the array is the "natural" order of LEDs, with the number being the electrical position of a given LED on the linear strand.

The ArduinoJSON library is extremely whitespace sensitive. If your ledmap1.json file is not working, check for white-spaces where they should not be.

Note: In the examples below, additional whitespace is added for readability; however, the examples may not work when copied and pasted directly due to this whitespace sensitivity.

LED positions are zero-indexed. If you have 20 LEDs, your LED "addresses" will start at 0 and end at 19, but they do not need to be entered in order or completely, as demonstrated below.

Additional configurations

Multiple maps are supported in the latest versions by using ledmapx.json, where x is a number. Maps can be selected in your cfg.json using {"ledmap":x,..., where x corresponds to the number in the filename, or in the main settings UI below segments, where any customised names will also be used in the selection list, see below.

Complicated maps

LEDs can be mapped in the "map" array in any order, including out-of-order, allowing you to map custom and complex shapes using -1 in the map for gaps/blank/null LEDs. In addition, not all LEDs in a segment need to be mapped in the map; you can leave out extra LEDs if they're not required.

Examples

Formatting options for "map"

In the examples below (formatted multiple ways), we remap a strip of four LEDs from a physical order of 0 1 2 3 into a new order of 0 2 1 3.

Single line

{"map":[0,2,1,3]}

Multi-line object, single line array

{"map":[
0,2,1,3
]}

Multi-line array, helpful in visualising 2D matrices

{"map":[
0,2,
1,3
]}

1D redordering example

This is another example that switches direction every 5 LEDs. It could be formatted in any of the three ways demonstrated above.

{"map":[0, 1, 2, 3, 4, 9, 8, 7, 6, 5, 10, 11, 12, 13, 14,
19, 18, 17, 16, 15, 20, 21, 22, 23, 24, 29, 28, 27, 26, 25]}

2D Matrix reordering

The following example shows how to create a ledmap1.json for LEDs arranged in a two-dimensional grid instead of a one-dimensional string. Notice the addition of the width and height keys and how they correspond to how the map array itself is formatted. This isn't required, but it is helpful to do.

Here, we have a serpentine of LEDs in 4 columns and 3 rows:

{
  "map": [
    0, 1,  2,  3,
    7, 6,  5,  4,
    8, 9, 10, 11
  ],
  "width":  4,
  "height": 3
}

A basic matrix map like the one above can also be quickly configured in the UI as a Gap, but if you need more control, this is a good starting point. As noted above, if an ledmap.json file exists, the 2d-gaps.json file will be ignored.

Also, while we've written it here as a multi-line array with the same number of lines as the height and the same number of entries per line as the width, you could still format it as a single-line file, as below; they are functionally the same.

{"map":[0,1,2,3,7,6,5,4,8,9,10,11],"width": 4,"height":3}

Mapping complex shapes using -1's for spacing

A more complex example of 16 LEDs arranged in a double figure ∞ shape. This includes some empty space represented as -1.

{"map":
  [
    -1, -1, 14, -1, 12, -1, 10, -1, -1,
    -1, 15, -1, 13, -1, 11, -1,  9, -1,
     0, -1, -1, -1, -1, -1, -1, -1,  8,
    -1,  1, -1,  3, -1,  5, -1,  7, -1,
    -1, -1,  2, -1,  4, -1,  6, -1, -1
  ],
  "width":  9,
  "height": 5
}

Naming your maps for easier use

In addition, you can name your map configs in the UI by adding an "n" key to the config.

{"n": "Double infinity map.",
"map":
  [
    -1, -1, 14, -1, 12, -1, 10, -1, -1,
    -1, 15, -1, 13, -1, 11, -1,  9, -1,
     0, -1, -1, -1, -1, -1, -1, -1,  8,
    -1,  1, -1,  3, -1,  5, -1,  7, -1,
    -1, -1,  2, -1,  4, -1,  6, -1, -1
  ],
  "width":  9,
  "height": 5
}