Some piano keyboards have a light under every key, and Chordzy can switch those light-up keys on for the notes you play next. Your eyes stay on your hands instead of the screen. Key lights are off until you turn them on.

Three choices work today: a ROLI Piano M or LUMI Keys, a Casio LK-S250, or another keyboard whose manual says a NoteOn message lights a key. We wrote each one from published notes on that keyboard's MIDI messages and tested it in software. We have not tried any of them on a real keyboard yet, and [the compatibility table](#which-keyboards-work) says so.

## Turning key lights on

Key lights live in the **Speakers** settings, under **Key lights**. The app has them on its hardware settings screen. The site puts them on your account's **Speakers** tab, once you press **Connect MIDI** with the keyboard plugged in over USB.

| Setting | What to choose |
|---|---|
| **Light-up keyboard** | Your model |
| **Light output** | The keyboard's own port (Chordzy's virtual port is never listed) |
| **Keyboard range** | The keys your keyboard covers |
| **Test lights** | C4, E4 and G4 light for 4 seconds; **Stop test** clears them sooner |

Light output and sound output may name the same port. The setting belongs to this computer, or this browser: a laptop you sign in on later shows **Off** until you set it up there as well.

For a keyboard that never shows up, the [MIDI keyboards](/help/hardware/midi-keyboards.md) page has the port and cable checks.

## What the lights show while you play

The lit keys are the notes due next. In Wait for Me the music stops until you play them, and a key stays lit until you press it. Play the whole chord and the next one lights.

Lights follow Listen too. There the keys light in time with the music, and Chordzy grades nothing.

A ROLI Piano M or LUMI Keys lights in color:

| Color | Meaning |
|---|---|
| Green | A note to play, when the music does not say which hand |
| Cyan | Right hand |
| Orange | Left hand |
| Blue | Already pressed, while the rest of the chord is still waiting |

The Casio and the NoteOn choice light a key without saying which hand.

## Range and light limits

A ROLI Piano M or LUMI Keys has 24 keys and octave buttons that shift them. Set **Keyboard range** to the octave the keyboard shows. The default, **Octave 0**, covers C3 to B4. Press the keyboard's octave-down button and Chordzy has to follow, to **Octave -1**, which covers C2 to B3.

The Casio LK-S250 lights at most 4 keys at once. A bigger chord shows four of its notes: the ones due soonest, right hand before left.

Chordzy never lights a key outside the range. When something does not fit, the status begins "Lit what fits" and says how many expected keys fell outside the range or over the light limit.

## Turning the lights off

Set **Light-up keyboard** to **Off** and every light goes out, and Chordzy lets go of the port. The screen before each piece has a **Key lights off** button for the same thing.

Pausing clears the lights as well. So do the last note of a piece, a switch to another window, and quitting. Keys that Chordzy did not light are left alone.

## When the browser asks about SysEx

The Casio LK-S250 lights its keys with Casio's own SysEx messages, and browsers keep those behind a separate permission. Chordzy asks for it at your first **Test lights** with the Casio picked. Decline, and the Casio still plays and gets graded with its keys dark, next to a note in the settings saying so. The browser's MIDI site setting is where that answer changes, and the [MIDI keyboards](/help/hardware/midi-keyboards.md) page has it for each browser, under "When the browser says MIDI is blocked".

A ROLI lights from plain NoteOn messages, with the velocity picking the color, so it never sets off that prompt. Nor does the NoteOn choice. If a browser cannot send MIDI at all, Chordzy points you to Chrome, Edge or the app.


## When the keyboard disconnects

Unplug the keyboard mid-piece and the lights stop. The settings say "The light output is not connected", and sound and input carry on. Plug it back in and Chordzy clears the range once, then lights only the keys due now.

Some keyboards send light commands back as if you had played them. Chordzy spots that and turns lights off for that setup, so a light can never count as a note.

A crash can leave keys lit. Any **Test lights** run clears them, and so does switching the keyboard off and on. Chordzy never writes to the keyboard's firmware or its settings.

## Which keyboards work

The **Light-up keyboard** menu has three choices after **Off**. We tested all of them in software against published protocol notes. None has met a real keyboard yet, and the menu says that too.

| Choice | Models | Lights at once | Tested on a real keyboard |
|---|---|---|---|
| ROLI Piano M / LUMI Keys | ROLI Piano M and LUMI Keys, the same hardware, on the stock program | 24 | Not yet |
| Casio LK-S250 | The LK-S250 only; other Casio models are not assumed to match | 4 | Not yet |
| Other keyboard (NoteOn lights) | A keyboard whose manual says a NoteOn on a chosen channel lights the key | Every key in range | Not yet |

Pick **Other keyboard (NoteOn lights)** only when the manual documents it. You also choose its **Light channel**, from Channel 1 to 16. On some keyboards the same message plays the note aloud.

Yamaha EZ keyboards and The ONE keyboards have lit keys too. Chordzy has no profile for either, and we have not tested them. The rest of the [hardware Chordzy works with](/help/hardware.md) is listed in one place.