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Replicant FX RFX Effects

What is RFX Effects?

RFX Effects is an animation engine for props and costumes — proton packs, gauntlets, helmets, badges, anything with lights, a screen, or a speaker. It runs on small ESP32-class boards and coordinates everything in real time: LED strips, LCD panels, sound playback, buttons, and the logic that ties them together.

The core idea: your whole show lives in one file, show.json. You flash the firmware once. After that, the firmware never changes — the JSON is your program. Change a color, add a button behavior, rewrite the entire state machine: just edit the file and reload. No compiler, no reflashing.

What a show looks like

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A show declares your hardware, then describes behavior declaratively. Here’s the heart of a “tap a button to toggle a rainbow” prop:

"scripts": {
  "idle": {                    // a looping background look
    "loop": true,
    "children": [
      { "comet": "@strip", "color": "hsv(time*0.1, 1, 1)", "lapSec": 2.0, "tail": 6, "loop": true }
    ]
  }
},
"states": {                    // the brain: when X happens, do Y
  "initial": "Off",
  "Off": { "on": { "go.tapped": "On" } },
  "On":  {
    "enter": [ { "start": "idle" } ],
    "exit":  [ { "stop": "idle" } ],
    "on":    { "go.tapped": "Off" }
  }
}

You describe what things are and when things happen; the engine handles the frame-by-frame animation, timing, audio mixing, and looping. Speed and intensity cascade down the tree — slow a script down and everything inside it, including audio pitch, slows with it.

What it runs on

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RFX Effects supports 11 boards, from a bare ESP32 devkit up to boards with built-in screens, audio, and SD storage — plus a desktop target so you can build shows with no hardware at all. See the board lineup for the full comparison.

Two ways to deploy

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Each device is set up for one of two update modes. Standalone (the default) updates over WiFi: open the device’s web page and upload new firmware from the Files tab — no cable needed. Loader mode needs no WiFi at all: the device exposes a USB drive, and you update by dragging a firmware.uf2 file onto it, with automatic recovery if a bad image ever crash-loops. Either way, show.json itself is just a file on the device — editing your show never requires a firmware update in the first place.

The web dashboard

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Every device serves its own dashboard over WiFi (at http://<name>.local/ or its IP). From it you can:

  • Press virtual buttons. Inputs without a physical pin show up as buttons on the dashboard — buttons light up only in states that respond to them.
  • Edit files live. The Files tab lets you edit show.json, upload sounds and fonts, and flash new firmware.
  • Check your work. Saving a show gives you an instant pass/fail validation banner, with the full report in the Console. A show with errors is rejected and the device keeps running the last good one — you can’t brick your prop with a typo.

Preview on your desk

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The same engine runs as a desktop preview: a browser-based visualizer with the same dashboard, virtual buttons, and a live view of your LED strips and screens. Edits to show.json hot-reload instantly. It’s the fastest way to write a show — build the whole thing on your computer, then copy it to the prop. See the desktop target for details.

Where to go next

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