Configure a Macro Keyboard on macOS

End-to-end workflow for cheap 3-key USB-C/Bluetooth macro pads (Jieli, Realtek, CH57x, AliExpress-class): identify the device, figure out what each button actually emits, write a Karabiner rule scoped to that device only, and handle USB + Bluetooth in one rule even when the pad's BT firmware emits different keycodes than its USB side.

Just want the turnkey recipe? references/09-turnkey-walkthrough.md is a copy-paste-ready 30-minute walkthrough that replicates the "MacroKeyBot" setup used as this plugin's worked example — tap/double-tap on all three buttons: top (Fn for Typeless toggle / Cmd+V paste), middle (Shift+Return / Return), bottom (up_arrow / down_arrow), across USB + Bluetooth. The bottom button uses two different mechanisms (USB: software discrimination; BT: pad-firmware discrimination via separate equal_sign / Option+Z keycodes) — see 03-patterns.md. Start there if you know what you want; come back here when you need the reusable workflow or deeper pattern references.

Self-Evolving Skill: If a step breaks on a new pad, fix this file immediately. Every dead-end discovered belongs in references/04-anti-patterns.md.

When to Use This Skill

• User mentions "macro pad", "macro keyboard", "3-key pad", "Stream Deck alternative" on macOS
• User wants to remap a cheap HID pad they bought from AliExpress / Amazon
• User wants buttons to emit Fn, Return, media keys, or custom shortcuts
• User hits a wall with BetterTouchTool (BTT can't emit real Fn — see sibling skill emit-fn-key-on-macos)
• User asks about dual USB + Bluetooth configuration for the same pad
• User mentions Jieli, Free3-P, or any pad with "USB Composite Device" as its product string

Prerequisite Check

# 1. Karabiner-Elements installed?
test -d /Applications/Karabiner-Elements.app && echo OK || brew install --cask karabiner-elements

# 2. Input Monitoring + Accessibility granted?
#    System Settings → Privacy & Security → Input Monitoring → Karabiner = ON
#    System Settings → Privacy & Security → Accessibility → Karabiner = ON

# 3. On macOS Sequoia+: Login Items toggle for privileged daemon
#    System Settings → General → Login Items → Allow in the Background → Karabiner-Elements Privileged Daemon = ON

If any of the three is off, the remap will silently fail to grab the device.

Workflow (5 Steps)

Step 1 — Identify the device (USB)

# USB product string, VID, PID, serial, interface layout
ioreg -p IOUSB -l -w 0 | grep -B 2 -A 40 "USB Composite Device" | head -80

# Or system_profiler for a human-readable dump
system_profiler SPUSBDataType | grep -A 15 "USB Composite"

Record: idVendor (hex), idProduct (hex), product string, serial, interface count.

Decode VID/PID → decimal for Karabiner (Karabiner's JSON uses decimal):

python3 -c "print(int('0x4c4a', 16), int('0x4155', 16))"
# → 19530 16725

See references/01-hardware-identification.md for full decode of a Jieli pad including the HID report descriptor and how to infer the chip family.

Step 2 — Identify the device (Bluetooth, if applicable)

Pair via System Settings → Bluetooth → Connect. Then:

# Pad's BT address + VID/PID + firmware
system_profiler SPBluetoothDataType | grep -A 20 "Free3-P\|<pad-name>"

# Confirm Karabiner sees it as a grabbable device
karabiner_cli --list-connected-devices | jq '.[] | select(.product == "<pad-name>")'

Expect different VID/PID than USB. Cheap pads borrow Samsung's 0x04E8 VID for macOS HID compatibility. Your one Karabiner rule must scope to both VID/PIDs via a single device_if with two identifiers.

See references/08-bluetooth-configuration.md for the Jieli/Free3-P live example.

Step 3 — Discover what each button actually emits

Do not assume the stock mapping. Cheap pads ship with arbitrary keycodes (Jieli/Free3-P ships as Ctrl+C/Ctrl+V/Ctrl+X — not cut/copy/paste convention — button order is hardware-random).

Use ignore: true diagnostic rule (zero-effect remap that logs raw events). See sibling skill diagnose-hid-keycodes for the full workflow. Quick version:

1. Add a disabled rule with "conditions": [{"type": "device_if", "identifiers": [{...}]}] and "ignore": true on the device
2. Open Karabiner-EventViewer → Main tab
3. Press each button, screenshot the emitted keycode
4. Repeat for BT (in each firmware mode if the pad has multiple)

Step 4 — Write the Karabiner rule

Location: ~/.config/karabiner/karabiner.json → profile 0 → complex_modifications.rules → append a new rule.

Backup first:

cp ~/.config/karabiner/karabiner.json ~/.config/karabiner/karabiner.json.bak.$(date +%Y%m%d-%H%M%S)

Rule skeleton (one rule, N manipulators = buttons × transports):

{
  "description": "<pad-name>: Top → Fn, Middle → Return, Bottom → Command+Delete",
  "manipulators": [
    {
      "type": "basic",
      "from": {
        "simultaneous": [{ "key_code": "left_control" }, { "key_code": "c" }],
        "simultaneous_options": {
          "detect_key_down_uninterruptedly": true,
          "key_down_order": "strict_inverse",
          "key_up_order": "strict_inverse",
          "to_after_key_up": []
        },
        "modifiers": { "optional": ["any"] }
      },
      "to": [{ "apple_vendor_top_case_key_code": "keyboard_fn" }],
      "conditions": [
        {
          "type": "device_if",
          "identifiers": [
            { "vendor_id": 19530, "product_id": 16725 },
            { "vendor_id": 1256, "product_id": 28705 }
          ]
        }
      ]
    }
  ]
}

(Repeat the manipulator block for middle, bottom, and the BT-mode variants — 6 manipulators for a pure 3-key pad × 2 transports; +2 manipulators per button per transport for each button that uses Karabiner-side tap-vs-double-tap discrimination (see references/03-patterns.md). The Jieli/Free3-P live example uses tap-vs-double-tap on all three buttons → 12 manipulators total. Note: the bottom button uses Karabiner-side discrimination on USB only (Ctrl+X for both presses); on BT the pad's firmware emits two different keycodes (equal_sign single, Option+Z double), so its 2 BT manipulators are simple immediate translations rather than a detector/handler pair. Total stays at 12 either way: 8 (top + middle, both transports, software discrimination) + 2 (bottom USB, software discrimination) + 2 (bottom BT, firmware-decided keycode translation). JSON does not support // comments, so do not paste comment lines into your config.)

Five rules to remember:

1. simultaneous with detect_key_down_uninterruptedly: true — needed when the pad emits modifier + key in one HID report. Default mandatory matcher misses these.
2. apple_vendor_top_case_key_code: keyboard_fn is the only way to emit real Fn. key_code: fn does nothing; modifiers: ["fn"] does nothing.
3. device_if with MULTIPLE identifiers — put the USB VID/PID and the BT VID/PID both in the same identifiers array. One rule handles both transports.
4. Scope every manipulator to the device. Without device_if, you'll remap your MacBook's built-in keyboard and break Apple's native keys.
5. modifiers: {"optional": ["any"]} — lets the firmware's modifier report flow through without blocking the rule.

Full live example (Jieli + Free3-P, 12 manipulators with tap/double-tap on all three buttons; bottom button uses asymmetric mechanisms — software discrimination on USB, firmware-decided-keycode translation on BT): references/raw/karabiner-rule.json.

Step 5 — Verify the grab + test

# Karabiner sees and grabs the device
karabiner_cli --list-connected-devices | jq '.[] | select(.product == "<pad-name>") | {product, is_grabbed}'

# Should return {"product": "...", "is_grabbed": true}

# Live event test
open -a "Karabiner-EventViewer"
# Press buttons → should see your TARGET keycode, not the SOURCE

If is_grabbed: false, re-check Input Monitoring + Accessibility + Login Items (step Prerequisite Check).

If grabbed but buttons pass through unchanged: your simultaneous matcher is probably wrong — the pad emits the combo in one report but you wrote mandatory. Revisit step 3.

If real Fn stops working system-wide after your rule loads: revert immediately. Do not set to_if_held_down with keyboard_fn as the target — this breaks Fn-emission on the whole system (verified failure). See references/04-anti-patterns.md → "Tap-vs-hold Fn emission".

Decision Tree: Which Target Keycode?

Handling Multiple BT Firmware Modes

Many cheap pads have 2-4 firmware modes that emit different keycodes per mode. The Jieli/Free3-P has 4 modes:

Pick the mode with the rarest keys (mode 4 for Free3-P — page_up/page_down are rarely used on laptops). Then add manipulators that match those keycodes plainly (no simultaneous needed for single-key firmware modes).

Mode-switch combos are often undocumented. Common attempts: hold all 3 keys ≥ 5s, hold top alone ≥ 5s, press top+bottom simultaneously. Document what works when you find it.

See references/08-bluetooth-configuration.md for the full mode-4 setup.

Deep References (load on demand)

Sibling Skills

• emit-fn-key-on-macos — focused coverage of why only Karabiner can emit real Fn (BTT / hidutil / QMK on locked firmware all fail)
• diagnose-hid-keycodes — ignore: true + EventViewer + Quartz focus-free screencap workflow for figuring out what a mystery button emits

Post-Execution Reflection

After this skill completes, reflect before closing the task:

0. Locate yourself. — Confirm this SKILL.md is the canonical file before any edit.
1. What failed? — Fix the instruction that caused it.
2. What worked better than expected? — Promote to recommended practice.
3. What drifted? — Update vendor IDs, keycodes, or FOSS-tool versions if reality disagrees with the doc.
4. Log it. — Add an evolution-log entry (or 04-anti-patterns.md row) with trigger, fix, evidence.

Do NOT defer. The next invocation inherits whatever you leave behind.