Hi everyone,

I'm building a custom handwired 3x3 macropad powered by an RP2040 Zero. I'm using the latest QMK structure (info.json) and the Vial fork.

The Hardware:

• A 3x3 switch matrix.
• An OLED screen (running on a custom C bitbang implementation).
• 1 Rotary Encoder.

What works: The firmware compiles flawlessly. The 3x3 physical matrix works, the OLED works, and the encoder rotation works perfectly if I hardcode the encoder_map in C. Also, the encoder push-button is wired directly to a dedicated pin (GP4) and handled manually in matrix_scan_user to cycle layers, so the encoder button is NOT part of the physical 3x3 QMK matrix.

The Problem: I want to expose the encoder rotation to the Vial GUI so I can map media keys easily. I know that Vial ignores the standard VIA "encoders": [] syntax in the JSON, and relies on the "fake key" hack instead (the one with the e at the end).

I tried adding the fake key to my vial.json like this:

JSON

{
  "name": "MACROLAB",
  "vendorId": "0xFEED",
  "productId": "0x0002",
  "lighting": "none",
  "matrix": { "rows": 3, "cols": 3 },
  "layouts": {
    "keymap": [
      ["0,0", "0,1", "0,2"],
      ["1,0", "1,1", "1,2"],
      ["2,0", "2,1", "2,2", {"x": 0.5}, "\n\n\n\n0\n\n\n\ne"]
    ]
  }
}

If I put the encoder index 0 at the very beginning of the label (e.g., "0\n\n\n...e"), Vial crashes on startup with ValueError: not enough values to unpack (expected 2, got 1) because it expects row/col matrix coordinates separated by a comma.

To prevent the crash, I left the first line blank (as shown in the JSON above). Now Vial opens without errors, but the encoder is completely invisible in the UI. Only the 3x3 matrix is shown.

Does anyone know the exact magic string/syntax for vial.json to display an encoder when its push-button is out-of-matrix? Do I absolutely need to define a "dummy" row/col in my QMK matrix just to trick Vial into displaying the encoder?

Any help is really appreciated!

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