Choowi 0.20.0 · the first firmware of the forge, for CHOMPI

Make your first sounds
with Choowi.

A small storybook tutorial for CHOMPI. Make a sound, chomp a little noise, shape it, loop it, and keep it—with Choowi at your side.

Ten adventures at Choowi’s bench

Come make something with me.

Keep CHOMPI beside you. Follow the actions at your own pace, listen for the result, and let Choowi help when you get stuck. Start with the choowi-0.20.0-rc3-card.zip release kit and its README-FIRST. This tutorial assumes Choowi is already installed; installation instructions are in the reference.

Chapter 01

The workshop wakes up

Choowi pulls a stool up to the bench. “Headphones first. We can make a big world out of a little sound.”

Try it together

  1. With Choowi installed, plug in headphones, switch CHOMPI on and turn SW6 up gently.
  2. Set the toggle down. Leave the menu closed for playing.
  3. Play a few keys. A saved or recalled preset may already be loaded; a fresh setup starts as pass-through.
What to listen or look for

You have a comfortable listening level. Silence on the keys is fine if no sound has been loaded yet.

Find the exact controls in the reference →
Chapter 02

The first spark

“Let’s see what the forge has in it today.” Choowi lifts his hammer. One small gesture, one new idea.

Try it together

  1. Toggle down, menu closed: hold SW1 + SW3 together for 1 s, then release.
  2. Play a few keys. Try a low note, then a high one.
  3. Like it? Stop rolling. Follow the save recipe below before trying another.
What to listen or look for

A new sound is ready. A roll can include harmony or an arp; a current recording can become a sampled instrument.

Find the exact controls in the reference →
Chapter 03

A shelf for your first sound

Choowi sets out a little jar. “Good ideas deserve somewhere to live. Let’s label this one.”

Try it together

  1. Toggle down and hold CHOMPI. Find the blue presets page: if needed, tap KEY_22 (D#4) to return to teal TAPE, then hold it for 1 s.
  2. While holding CHOMPI, turn SW4 to choose a preset bank: red, orange, yellow, green, teal, blue, purple, pink. Choose a slot you can overwrite; dim white keys already hold presets.
  3. Press KEY_25 (A#4), release CHOMPI, then press your destination white key. It turns blue.
  4. Press CHOMPI to confirm. Wait 2 s before switching off.
  5. To check it: make another roll, then hold CHOMPI on the blue page, press your saved slot and release CHOMPI.
What to listen or look for

Green flash means saved; red means failure. Recalling the slot brings your sound back.

Find the exact controls in the reference →
Chapter 04

Feed me a sound

“A clap? A hum? That mug on your desk?” Choowi opens his enormous mouth. “Bring me a little noise.”

Try it together

  1. Unplug line in to use the mic, or connect your sound source to line in. Set the toggle up.
  2. Hold CHOMPI through the three red blinks (1.5 s). Make your sound when the light becomes steady red.
  3. Release CHOMPI to stop. Toggle down and play the recording across the keys.
  4. To keep it: hold CHOMPI on the teal TAPE page, choose your sample bank, press KEY_25, release CHOMPI, choose a card slot (C3–B4) you can overwrite, then press CHOMPI. Sample banks are purple, orange, teal, red and lime; saving over bank purple replaces Choowi’s samples.
  5. On teal TAPE in chromatic mode, select that saved card sample. Then save your project on the blue presets page.
What to listen or look for

Your take plays at different pitches. A green flash after the sample save means the audio was written to the card.

Find the exact controls in the reference →
Chapter 05

At the tinker bench

Choowi slides his wrench across the table. “Same sound, different shape. Listen to one little change at a time.”

Try it together

  1. With the menu closed, play a note and turn SW5 slowly left, then right.
  2. Press and release a top knob to move to its next page. Use the knob-page chart below to find its job.
  3. On a sampler sound, try SW1 page 1 for sample start and SW2 page 1 for sample end.
  4. Save the sound you like. Sample-slot edits can also be written to the slot’s own settings.
What to listen or look for

SW5 changes the filter: left gets darker, right opens it. Moving start/end changes the part of a sample you hear.

Find the exact controls in the reference →
Chapter 06

The colour lantern

Choowi lights a lantern. “One note can have friends. Let’s invite a chord.”

Try it together

  1. Use a synth or chromatic sampler sound. With the menu closed, hold SW1 + SW2 for 1 s to toggle harmony.
  2. A green knob flash means on; red means off. Play a few keys and listen for chords.
  3. For the settings: hold CHOMPI on teal TAPE, then hold KEY_21 (C#4) for 1 s to reach the purple harmony page.
  4. Release CHOMPI to play again. Save your project when you like it.
What to listen or look for

A key plays a chord when harmony is on. The key colours show chord types: orange major, blue minor, red diminished.

Find the exact controls in the reference →
Chapter 07

Around, and around

Choowi draws a circle on the bench. “You play once. The loop remembers the sound. Then you can play beside it.”

Try it together

  1. Toggle down, menu closed. Tap LOOP and play a short phrase.
  2. Tap PLAY to end the take. Listen to it repeat.
  3. Tap LOOP to overdub, play another layer, then tap LOOP again to leave overdub.
  4. Tap PLAY to pause or resume. Hold PLAY + LOOP for 2 s only when you want to clear the loop.
  5. To keep the audio: hold CHOMPI on teal TAPE, press KEY_24, press LOOP as source, release CHOMPI, choose a destination white key, then press CHOMPI.
What to listen or look for

The first phrase repeats. LOOP turns yellow while overdubbing. An audio loop must be saved as a sample to survive power-off.

Find the exact controls in the reference →
Chapter 08

Leave the workshop ready

Choowi puts his hammer down. “Before we close up, let’s make sure tomorrow’s you can find everything.”

Try it together

  1. Save any RAM recording or audio loop you want to keep as a sample.
  2. Select the saved card sample if the project uses it, then save the project on the blue presets page.
  3. Recall your saved slot to check it. Allow 2 s after saving or recalling before switching off.
  4. If something is quiet, check SW6 volume and your loaded sound. For stuck notes, hold SW4 + SW3 for 1 s.
What to listen or look for

Your sound has a place on the card. The last saved or recalled preset becomes the startup sound; its event loop waits until you recall the slot.

Find the exact controls in the reference →
Chapter 09

A drawer full of purple

Choowi opens a drawer. “I brought some sounds of my own. Try one before you record over it.”

Try it together

  1. Install the samples from the card zip. With toggle down, hold CHOMPI and reach teal TAPE (tap KEY_22 from a Forge page).
  2. For an instrument, press KEY_16 (C#3) until it glows purple, press a white key, then release CHOMPI to play.
  3. For drums, press KEY_17 (D#3) until it glows purple, then release CHOMPI: each white key plays a hit.
What to listen or look for

Purple holds 14 chromatic instruments and 14 kit hits (CC0). Sample banks: purple, orange, teal, red, lime. Preset banks use a separate eight-colour sequence.

More controls in the reference →
Chapter 10

A sound from a sentence

Choowi opens a window onto the forge. “Tell me how it should feel. A chatbot can help us write the recipe.”

Try it together

  1. Open Choowi’s forge page in Chrome or Edge on a computer. Plug in CHOMPI and press Connect; allow MIDI including SysEx.
  2. Describe the sound and press Copy the prompt. Paste it into any chatbot. Copy its whole reply back and press Use this reply.
  3. With live audition enabled, play CHOMPI and tweak the settings. No API key is needed on the forge page.
  4. Choose a preset bank and white-key slot, then press Save to CHOMPI. A used slot needs replacement confirmation. Wait for the saved message, then recall it on the panel. Save JSON keeps a file on the computer instead.
What to listen or look for

Live audition sends the current sound; saving stores it on the card.

More controls in the reference →

A sound of your own.

That’s the first little adventure. Explore the reference whenever you want another tool from Choowi’s bench.

Open the controls and reference
Controls, diagrams & full reference

Quick start

  1. Plug in headphones, switch CHOMPI on and turn SW6 (volume) up a little. CHOMPI wakes up singing: it loads the last preset you used and plays a little chime while a rainbow runs across the keys. The very first time, before any preset has been used, it starts as a clean pass-through.
  2. No sound yet? Hold SW1 + SW3 for a second: surprise me rolls a brand-new sound. Or record one (toggle up, hold CHOMPI through the red count-in), recall a preset (toggle down, hold CHOMPI, hold KEY_22 1 s, press a lit white key), or send one from the computer with Forge Bridge.
  3. Play the 25 keys. Turn the knobs; press and release a knob for its next page.
  4. Stop everything: hold SW4 and SW3 together for 1 second (panic).

Hi, I'm Choowi, the forge's blacksmith. Stuck for a sound? Hold SW1 + SW3 and I'll forge you a new one.

The panel

The names below are the ones this manual uses. White keys are KEY_1–KEY_15 (C3 to C5), black keys KEY_16–KEY_25 (C#3 to A#4).

CHOMPI's controls in their real order, left to right (proportions approximate). Hold SW4 + SW3 for 1 s to stop all sound; the toggle decides what the CHOMPI key does.
ControlNormal playIn the menu (toggle down, hold CHOMPI)
25 keysPlay notes, full velocity (as TAPE)Pick slots and functions: see the menu pages
CHOMPI keyToggle up + hold: record, after a 1.5 s count-in. Toggle down, quick tap: the event recorder's record / stop / playToggle down + hold: open the menu (its light shows the page). Press: confirm
SW4 · SW1 · SW2 · SW3Turn: the knob's page. Press and release: next page. Hold 1.5 s: reset that controlTAPE's second layer (pitch steps, window, delay time…). SW4 also turns the preset bank
SW4 + SW3, 1 sPanic: stops all sound—
SW1 + SW2, 1 sHarmony on / off (knob lights flash green / red)—
SW1 + SW3, 1 sSurprise me: a new sound; keep holding for another every 1.5 s—
SW2 + SW3, 1 sMutate: the sound drifts a little; keep holding to drift further—
SW5Turn: filter cutoff (about 80 Hz–8 kHz, resonance rising as it closes), and the loop's tone with it. Push and turn (with a loop): loop speed, scrub when paused. Click: speed back to 1×Loop speed
SW6Turn: volume. Short press: input gain (light blue → red) and back. Hold 2 s: battery lightOutput compressor; press: monitor position
PLAY · LOOPThe looperOverdub feedback − / +
Line in jackPlugged in: records from line in. Unplugged: the mic—

Knobs and knob pages

TAPE's pages come first, then Forge's synth controls. Press and release a knob to step to its next page; its light shows the page. Hold it for 1.5 s without turning to put that control back to the preset's value. One click moves 3 % on SW1–SW3, as on TAPE.

Synth patches. On sampler patches page 1 is TAPE's: pitch (SW4), sample start (SW1), sample end (SW2); SW1 page 2 is attack, SW2 page 2 release and page 4 loop crossfade. A patch can add its own control as each knob's last page.

One colour rule

Wherever you pick from a list or step through pages, the colours go in the same order: the 1st is always white, the 2nd green, and so on. Pressing a knob to its next page flashes that page's colour for a moment, then the light shows the value again.

Pitch, gain, saturation and the DJ filter are performance settings, as on TAPE: they stay when you change presets and reset at power-on.

TAPE's menu page

Exactly as stock TAPE: sample slots, recording sources and the sample functions. Sample banks go by colour on KEY_16 (chromatic) and KEY_17 (kit): purple, orange, teal, red, lime. Choowi's own sounds live in bank purple (14 instruments, 14 drums; choowi-samples.zip on the release page).

White keys: chromatic, load and play that slot (KEY_15 is the recording); kit, pick a slot for save, copy or erase. Save, copy and erase finish with a press of CHOMPI.

The knobs while the menu is open

KnobTurnPress
SW4Pitch in fifths and octaves (page 2: pan)Pitch back to 1×
SW1 / SW2Move the start–end window together (synth: attack and release)SW1 auto-loop: off, loop (white), loop chords (purple: a held chord repeats as one) · SW2 sustain (white when on)
SW3Delay time (page 2 Texture, TAPE's warble; page 3 DJ filter resonance)All effects back to default
SW5Loop speed, also while pausedSpeed back to 1×
SW6Output compressorMonitor: orange headphones · blue both · yellow send/return

Presets on CHOMPI

8 banks × 15 slots on the SD card, by colour: red, orange, yellow, green, teal, blue, purple, pink. From TAPE's page, hold KEY_22 for 1 second. Occupied slots glow dim, the last recalled one white.

ToDo
RecallHold CHOMPI, press a white key, release CHOMPI
SaveKEY_25, release CHOMPI, a white key (blue), CHOMPI → green flash
CopyKEY_24, source key (green), change bank if you like, destination (blue), CHOMPI
EraseKEY_23, a white key (red), CHOMPI
CancelPress the same function key again

Saving a preset also saves the event recorder's loop, harmony, arp, bass and tempo: together that is a project.

MIDI program change on channel 1 recalls slots too: program = (bank − 1) × 15 + (slot − 1).

All white keys red means no usable SD card.

Wakes up singing: CHOMPI remembers the last preset you recalled or saved and loads it at power-on (its recorded loop waits until you recall the slot).

Recording

  1. Toggle up, the record position. The CHOMPI light becomes the input meter and you hear the input in the headphones.
  2. Hold CHOMPI. CHOMPI and the white keys blink red three times (1.5 s count-in). Letting go now records nothing.
  3. Recording starts when the blinking stops (CHOMPI red). Release to stop. The keys play the take at once, chromatically and normalised.

Too quiet or distorted? Short-press SW6 and turn it for input gain (75 % at power-on), short-press again for volume. Up to about 87 s. The take stays until power-off; save it to a slot with KEY_25 on TAPE's page to keep it.

Looper

DoResult
Tap LOOPStart the first take (PLAY teal, LOOP red)
Tap PLAYEnd the take; the loop plays
Tap LOOP insteadEnd the take and go straight into overdub (TAPE habit)
LOOP while playingOverdub on / off (LOOP yellow)
PLAY while playingPause / resume. Hold 2 s while paused: back to the start
Hold PLAY + LOOP 2 sClear the loop
PLAY + LOOP, no loop yetArmed: recording starts with the first note
SW5 push and turnLoop speed (below zero plays backwards); paused: scrub. Click: 1×
SW5 turnThe cutoff, and it darkens or opens the playing loop too (the recording itself is untouched)

Up to about 83 s. Everything you hear goes into the loop. A new loop always starts at normal speed and fully open. SW5's lights: the loop speed while it plays; dim white while paused, the direction lighting up as you scrub; after a plain turn, the cutoff for a second (purple closed → white open). Panic pauses it without losing it. To keep a loop as a sample: TAPE's page, KEY_24, LOOP, a white key, CHOMPI.

Harmony: one key, one chord

Each key plays a whole chord in the key you choose, through the instrument and to MIDI out. Synth patches and the chromatic sampler. Quick on / off: hold SW1 + SW2 for 1 s. Settings: TAPE's page, hold KEY_21 for 1 s (purple); here a key sets the tonic, which lights white, its scale blue.

The keys show the chords. With harmony on, every key glows in the colour of the chord it plays: orange major, blue minor, red diminished, pink augmented, teal sus4. Hold Shift and they change to show the shifted chords.

The keys tell you what they play: orange happy (major), blue moody (minor), red tense. Hold Shift and watch them change.

Static layout (the default) in C major, menu closed, coloured as CHOMPI lights them. The white keys C3–B4 are the chords I to vii twice; C5 is Shift. In Real layout the key you press is the chord's root.
KnobTurnPress
SW4Mode: major, natural / harmonic / melodic minor, dorian, phrygian, lydian, mixolydian, locrianHarmony on (green) / off (red)
SW1Chord size: fifth, triad, 7th, 9th, 11th, 13thLayout Static (white) / Real (orange)
SW2Inversion 0–3 (when voice leading is off)Voice leading on (white) / off (purple)
SW3—Open spread on / off

While you turn SW4, SW1 or SW2 its light shows the value in the colour rule: the 1st mode or size white, the 2nd green, the 3rd yellow…

Shift (hold C5 while playing): a dominant becomes its tritone substitute, a major chord sus4, a minor chord the dominant on the same root, a diminished chord the key's V7.

Arp, bass and tempo

An arpeggiator plays the held keys (or the harmony chord) on CHOMPI's clock; a bass part plays the chord's root under it, on MIDI channel 2. Open: TAPE's page, keep holding KEY_21 for 2 s (orange); or from the harmony page tap KEY_21.

KnobTurnPress
SW4Tempo, 1 BPM a click (40–300). While turning: under 80 blue, 80–99 green, 100–119 yellow, 120–139 orange, 140+ redTap tempo
SW1Arp octaves 1–4 (white, green, yellow, orange)—
SW2Arp gate 5–100 %—
SW3Bass rate: per chord (white), 1/2 (green), 1/4 (yellow), 1/8 (orange)Bass octave C1 → C2 → C3

MIDI clock in (USB or the jack) takes over the tempo, with start, stop and continue; the SW4 light blinks blue. On its own tempo CHOMPI sends MIDI clock, so other gear can follow.

Event recorder and projects

Records what you play, keys, MIDI notes in and knob moves, on the clock, and loops it over 1–8 bars. It plays back like a second player: through harmony, the arp and the bass, and out of MIDI. It is separate from the audio looper. The controls are the parts page's F#4, G#4 and A#4.

Arm on the parts page, release CHOMPI and play; to close the loop just tap CHOMPI (toggle down). The same tap stops it and plays it again. Opening the menu and pressing F#4 still works. Up to 1,024 events; a take closes by itself after 8 bars. Saving a preset saves the loop beside it.

The synth page

Design a sound on CHOMPI itself. Open: on TAPE's page keep holding KEY_21 until CHOMPI turns pink (3 s), or tap KEY_21 on the harmony or parts page. Hold C5 to hear your changes. Save as a preset to keep them.

My Tinker Wrench: pick the waves, hold C5 to hear it, then save it as a preset so it stays.

KnobPage 1 (pink)Page 2 (teal, press to switch)
SW4Oscillator 2 levelVibrato depth
SW1Oscillator 2 detuneLFO → volume
SW2NoiseLFO speed
SW3GlideDelay time

The FX page (0.20)

Four effect modules run in a row on everything CHOMPI plays: Space, Colour, Texture and Motion, with three effects each. Open: toggle down, hold CHOMPI, tap KEY_21 past the synth page until CHOMPI turns green. The keys play nothing here.

Module (knob)KeysTurnHold the knob + turn
Space (SW4, white)C3 echo + room · D3 cloud · E3 tape echoamountdelay time and room / cloud size
Colour (SW1, green)F3 saturation · G3 fold · A3 crushamountfold: bias · crush: lower sample rate
Texture (SW2, yellow)C4 cassette · D4 broken · E4 squashamounthiss and wear · longer dropouts · slower release
Motion (SW3, pink)F4 chorus · G4 phaser · A4 tremoloamountspeed

Your own order

Tap A#3: it and the effect keys blink. Tap one key of each module in the order you want the sound to go through them; each placed module stays lit, first brightest. The fourth tap locks the order and the keys pick effects again. Tap A#3 again to finish early. Hold A#3 1 s for Classic (Colour, Motion, Texture, Space). B3: side by side (the reverb hears your sound before the delay). F#3 / G#3: effects before / after the looper.

Taking an effect out

Turn its knob down until its ring is dim: the module is off wherever it sits, and the order and the chosen effect stay for when you turn it up again. Saving a preset keeps the whole FX section.

The sound

Virtual analog synth

Two oscillators (sine, triangle, saw, square; interval and detune), noise, a resonant low-pass per voice with its own envelope, an amp envelope with velocity, an LFO (sine, triangle, square, sample-and-hold) to pitch, filter or level, glide, and a voice count set by the patch.

Sampler

TAPE's sample files from the card (jammi_… chromatic, cubbi_… kit), up to seven voices, with each slot's own settings shared with TAPE in presets.json.

The forge webpage

Open the forge page in Chrome or Edge: Connect → describe → Copy the prompt → any chatbot → Use this reply → live audition and tweak → choose bank/slot → Save to CHOMPI. Save JSON keeps a computer file. No API key is needed.

Patches

The knobs tweak a sound and the presets page saves it. Waveforms, oscillator 2's interval, LFO shape, voices and glide come from the patch: make it in Choowi's sound workshop on the computer, by hand or by describing it to any chatbot.

Magic

Wakes up singing

Switch CHOMPI on and it comes back with the last preset you used, plays a little four-note chime through it, and runs a rainbow across the white keys.

Surprise me

Out of ideas? Hold SW1 + SW3 for a second: a brand-new sound, sometimes with chords in your key, sometimes with an arp, sometimes a gliding solo voice. Keep holding and it rolls another every 1.5 s; let go on one you like. Your volume, key and tempo stay put. The knob lights flash new colours each roll.

Chords and arp come and go, on purpose. Each roll decides them too: about 1 roll in 4 turns harmony on, about 1 in 5 starts the arp, and a roll that doesn't pick them switches them off, even if you had them on. Want chords on a rolled sound? Switch harmony on yourself (SW1 + SW2), then save. Mutate leaves them alone.

Mutate

Hold SW2 + SW3: the sound you have shifts a little, brighter or darker, longer or shorter, a different echo, so it drifts instead of starting over. Keep holding to drift further. The knob lights flash teal.

Chomp to instrument

Record anything, your voice, a door, a cup, then hold SW1 + SW3: the roll keeps your recording and builds an instrument around it, often with chords in your key and an arpeggio. The keys sparkle with every roll.

Dream & nap

Hold SW4 + SW1 for a second: Dream plays an ambient piece on its own, following your sound (pads get slow chords, plucky sounds drifting clusters, a kit soft patter), while the keys glow in the chord's colours and the knobs breathe. Hold them again, or press a key, to stop. Leave CHOMPI alone for two minutes and it takes a nap, humming quietly in your key until you come back (any MIDI arriving wakes it).

Like it? Save it to a preset slot. Neither gesture changes a knob page. When a loop closes, a green ripple runs out from the middle key.

What the lights mean

CHOMPI key

At power-on a rainbow runs across the white keys with the chime. With harmony on, the keys glow in their chord's colours (see Harmony).

SW6: battery and warnings

Safe mode

Safe mode means Forge crashed three times within 10 seconds of starting, so it started without the card's settings, presets and samples. Playing still works and the card is untouched. Copy FORGE/RESTARTS.TXT off the card, then switch off and on.

Power and battery

The power switch turns CHOMPI on and off. Some power banks do not charge while CHOMPI is on; charge switched off for now. A USB-C wall charger is faster than a computer.

Battery level: hold SW6 for 2 s. Only white means full. Green = fine (above about 3.3 V, most of the charge), yellow = getting low, red = nearly empty. They are voltage bands, not a percentage: checked at switch-on, then every 30 s; while charging the colour does not climb until it turns white.

Over USB: python host/forge_host.py battery prints the level, USB power, charging and whether a firmware install is allowed. Connect CHOMPI in the bridge shows it too.

Low battery: the knob and CHOMPI lights flash amber for 15 s, then CHOMPI shuts down. Plugging in during the flashing cancels it. Afterwards the switch alone won't wake it: plug in USB.

Storage mode (as stock): hold CHOMPI + PLAY + LOOP while switching on.

Use a USB-C charger or a charged battery. When using a power bank, charge with CHOMPI switched off. If CHOMPI stays dark after restarting: plug in a charger, switch off, wait 5 s, then switch on.

Installing and updating

First install: SD card

  1. Charge first: the SW6 battery light green or white.
  2. Back up the card. In its top folder rename every file whose name contains .bin, e.g. CHOMPI_TAPEv2_0.bin → CHOMPI_TAPEv2_0_bin.old.
  3. Copy FORGE.bin to the top folder.
  4. Card in, power on: rainbow lights while it installs, then Forge starts.

Updates: over USB

  1. Forge Bridge → Connect CHOMPI → Card & firmware → Install this kit's firmware.
  2. When the CHOMPI key blinks white, press it within 15 s.
  3. CHOMPI restarts and installs. Connect CHOMPI shows the new version and build, e.g. Forge 0.19.0 (build 7efb87e). If it stays all white after the install, switch it off and on.

Back to stock TAPE: rename CHOMPI_TAPEv2_0_bin.old back to .bin, remove FORGE.bin, power on.

Choowivision: CHOMPI's screen on your phone (0.20)

The forge page's Choowivision draws this same panel live while you play: every light in its colour, the page you're on, what each key and knob does there, the chord harmony just played, the looper and the battery. Plug CHOMPI into an Android phone with a USB-C OTG cable, open the forge page, tap Choowivision, then Connect (Chrome; iPhones have no Web MIDI). Sideways gives the biggest panel. It only watches: nothing on it changes CHOMPI.

Choowi's workshop

Every Forge release is a magic tool Choowi forges, in the next colour of CHOMPI's panel row: green, yellow, orange, red, then pink, purple, blue and teal. Small updates are small tools.

Colour Lanternforge 0.16Every page and setting shows its colour.
Wake-up Bellforge 0.17Wakes up singing; the lucky die rolls surprise sounds.
Sweep Brushforge 0.17.1Sweeps the filter so you hear it move.
Dream Bellowsforge 0.18Breathes slow dreams into CHOMPI when you leave it alone.
Tinker Wrenchforge 0.19Builds a sound right there on the panel.
Choowivisionforge 0.20Puts CHOMPI's panel on your phone, and four effects in your order.

Glossary

The words the manual, the guide, the forge page and Choowivision use, arranged by page and function (Choowi

0.20). Some words mean different things in different places: those come first.

Same name, different meaning

Key
a key on the panel (C3 to C5, the black KEY_16 to KEY_25) — or the musical key your chords are in (C major, A minor), set on the harmony page.
Page
a menu page (TAPE's, presets, harmony, arp · bass, synth, FX; the CHOMPI light's colour) — or a knob page, one of a knob's several jobs (press the knob to step).
Bank
a preset bank (8, by colour: red to pink) — or a sample bank (5, by colour: purple, orange, teal, red, lime). Different lists.
Slot
a preset slot (one of 15 white keys in a preset bank) — or a sample slot (a white key on TAPE's page; C5 is the recording).
Loop
the looper's recorded audio — or TAPE's auto-loop of a held sample (SW1 on TAPE's page: off, loop, loop chords).
Speed
SW4's first page, TAPE's pitch of the sound — or the loop speed (push and turn SW5) — or Motion speed on the FX page (hold SW3 and turn).
Record
recording a sample (toggle up, hold CHOMPI) — or the looper's take (LOOP) — or the event recorder (F#4 on the arp · bass page), which records what you play, not audio.
Overdub
adding a layer on the looper (LOOP while it plays) — or on the event recorder (G#4 on the arp · bass page).
Clear
the looper (hold PLAY + LOOP 2 s) — or the event recorder (A#4 twice on the arp · bass page).
Filter
the sound's own filter (SW5: darker or brighter) — or TAPE's DJ filter (SW3's third page: low-pass one way, high-pass the other).
Resonance
the filter's ringing edge (SW4's third page) — or the DJ filter's resonance (on TAPE's page).
Tremolo
on the synth page, LFO → volume (each voice wobbles) — or on the FX page, the tremolo effect (the whole mix pulses side to side).
Space
SW3's first page, TAPE's reverb + delay — and the Space module on the FX page. The same control in two places.
Colour
a light's colour (what the lights mean) — or the Colour module on the FX page (also SW3's second page).
Saturation
the Colour module's first effect, warm drive (SW3's second page used to be called this).
Gate
the arp gate (how long each arp note sounds) — or a sample's hold setting (sounds while held, or plays to the end).
Order
the FX order (A#3 on the FX page) — or the arp's as played pattern (G3 on the arp · bass page).
Before / after
the effects before or after the looper (whether the loop records them). Nothing to do with the compressor, which always comes last.

Playing (toggle down, menu closed)

Toggle
the switch by the CHOMPI key. Down is the menu position (you play; holding CHOMPI opens the menu). Up is the record position.
CHOMPI key
hold it (toggle down) to open the menu; let go to close it; press it to confirm a save, copy or erase. A quick tap works the event recorder.
Knob page
each of the four top knobs has several jobs; press and release a knob for its next one, hold it 1.5 s to put that control back. Its light shows the page.
Performance control
a knob setting that belongs to CHOMPI, not the sound (pitch, gain, the DJ filter, as on TAPE): not saved in presets.
SW5
the filter (turn); with a loop, push and turn for the loop's speed; click for normal speed.
SW6
volume; short press for input gain; hold 2 s for the battery light.
Panic
hold SW4 + SW3 for a second: every sound stops.
Surprise me
hold SW1 + SW3: a brand new sound, sometimes with effects (keep holding for another).
Mutate
hold SW2 + SW3: the sound drifts a little; keep holding to drift further.
Harmony on / off
hold SW1 + SW2 (the knob lights flash green / red).
Dream
hold SW4 + SW1: CHOMPI plays an ambient piece on its own, in your sound and key. A key stops it.
Nap
after two quiet minutes unplugged, CHOMPI rests until you touch it.

Record position (toggle up)

Recording a sample
hold CHOMPI through the three red blinks (the count-in), then make your sound; let go to stop. The keys then play it.
Input meter
the CHOMPI light while toggled up: how loud the input is.
Input gain
how loud the microphone or line in comes in (short press SW6, then turn).

TAPE's page (teal)

TAPE
the stock CHOMPI firmware Choowi grew from; its controls are kept where they were.
Chromatic
one sample played across the keys at different pitches (KEY_16; tap again for the next bank).
Kit
one sample per white key, for drums (KEY_17).
Record source
microphone, line in, or resample (record what CHOMPI itself plays).
Recording (C5)
your last recorded sample; it stays in memory until you switch off, unless you save it to a slot.

Presets page (blue)

Sound (or patch, preset)
everything that makes CHOMPI sound the way it does, saved together (the effects too).
Recall
hold CHOMPI, press a slot, let go. The last sound saved or recalled is the one CHOMPI wakes up with.
Save / copy / erase
A#4 / G#4 / F#4, then the slot(s), then press CHOMPI.

Harmony page (purple)

Harmony mode
one key plays a whole chord, built from a musical key and mode.
Tonic
the home note (any key on the harmony page sets it). Mode: the scale (major, minor, dorian…).
Chord size
fifth, triad, 7th, 9th, 11th or 13th: how many notes each chord has.
Roman numerals
a chord's place in the key: I is home, V the strongest pull back to it. Lower case (ii, vi) means minor; ° diminished.
Secondary dominant (V/ii, V/V…)
a chord that pulls strongly towards another chord of the key.
Borrowed chord (♭VII, iv, ♭VI…)
a chord from the parallel key, for colour. ♭II is the Neapolitan.
Static layout
the white keys are the key's chords I to vii, twice. Real layout: the key you press is the chord's root.
Shift
C5 in the static layout: hold it for the shifted chords.
Inversion, voice leading, open spread
how a chord's notes are stacked; voice leading moves each chord as little as possible from the last.

Arp · bass page (orange)

Arp (arpeggiator)
plays the held notes one at a time in a pattern (up, down, as played…) at a rate (1/8, 1/16…, t for triplets). Gate: how long each note sounds. Latch: keeps going after you let go.
Bass part
plays the chord's root (or root and fifth) underneath, in its own octave.
Tempo (BPM)
beats per minute. Tap tempo: tap it in (C5). MIDI clock: another device setting CHOMPI's tempo.
Event recorder
records what you play (notes, knob moves), not the audio; saved with a preset.

Synth page (pink)

Synth
CHOMPI's own oscillators making the sound. Sampler: playing sample files instead.
Oscillator
the source of the tone; its wave (sine, triangle, saw, square) sets its colour. Oscillator 2 adds a second one at an interval (a fifth, an octave…), slightly detuned for width.
Noise
a hiss you can blend in.
Voices
how many notes can sound at once. Mono is one, with glide sliding between notes.
Envelope
how a note grows and fades: attack (how fast it starts), decay and sustain (where it settles while held), release (how long it rings after you let go).
LFO
a slow wobble that moves pitch (vibrato), the filter, or the volume (LFO → volume). The mod wheel can control how much.

FX page (green)

Module
one of the four effect slots: Space, Colour, Texture, Motion. Each has three effects; one is chosen.
Space
echoes and room. Echo + room (delay with reverb), cloud (a huge smeared wash), tape echo (repeats that wobble and darken).
Colour
drive and grit. Saturation (warm), fold (glassy, metallic), crush (fewer bits, lo-fi).
Texture
wear. Cassette (tape warble, hiss), broken (random dropouts), squash (heavy pumping compression).
Motion
movement. Chorus (wide, lush), phaser (sweeping swirl), tremolo (the level pulses side to side).
Amount
how much of a module you hear (its knob). All the way down, the module is off.
Character
a second setting per module: hold its knob and turn.
Order
the order the sound goes through the modules; each works on the one before's sound. Classic is Colour, Motion, Texture, Space. Tap A#3 to choose your own.
Side by side (B3)
normally the reverb comes after the delay, so every echo gets reverb too and the echoes blur into a wash. Side by side feeds the delay and the reverb separately: crisp, dry echoes with a room behind your sound. Good for plucks, drums and fast arps; leave it off for dreamy washes.

Looper (PLAY and LOOP)

Looper
records what you hear as audio and plays it round and round. Take: the first recording (LOOP to start, PLAY to end it).
Overdub
a layer on top (LOOP while it plays). Undo: tap PLAY + LOOP together to take the last overdub back.
Pause / resume
PLAY while it plays. Clear: hold PLAY + LOOP 2 s.
Overdub feedback
in the menu, PLAY and LOOP set how much the old layers fade with each pass.

The web pages

Forge page (Choowi's forge)
describe a sound, any chatbot writes it, hear it live on CHOMPI, save it.
Choowivision
CHOMPI's panel on your phone or computer, live, with what every key and knob does on the page you're on (hover or tap for more).
Web MIDI
how the browser talks to CHOMPI over USB (Chrome or Edge; Android phones, not iPhones).
OTG cable
a USB-C cable or adapter that lets a phone talk to a USB device like CHOMPI.
v8 sound
the 0.20 format, with the FX section. Older Choowi (0.19) can't load it.
Card
CHOMPI's SD card: the firmware (FORGE.bin), samples and presets live there.

Troubleshooting

Something odd? Hold SW4 + SW3 to stop all sound first. Still stuck? Switch CHOMPI off and on; I'll be right back with your last sound.

You seeWhat to do
Keys play nothingNo sound loaded yet (only before the first preset): hold SW1 + SW3, record, recall a preset or send one
It started with an old soundThat is the last preset you used (wakes up singing). Recall another, or roll one with SW1 + SW3
All white keys red in the menuSD card missing or unreadable; reinsert it
A sample doesn't playExact name, in the card's top folder (cubbi_a1.wav), not in a folder
Magenta flashes at startSafe mode (see the lights section)
CHOMPI loses powerUse a USB-C charger (2 A or more) or a charged battery. Save sounds you like. Switch back on to return to your last saved or recalled preset.
Dark after an install; only the red charge lightThe battery wait: USB-C charger, switch off, 5 s, switch on
Computer doesn't see CHOMPI right after power-onGive it a minute, or unplug and replug the USB cable. Use a data cable, straight into the computer
Bridge can't find CHOMPIClose other MIDI programs, then Connect CHOMPI again