4 Sample Slots · 12 Voices · Multisampling · Realtime Sequencer · Sample Editor · MIDI · USB · Phoenix Librarian
Version 1.0.2 FINAL
RealTimeAudioLab / RTAL
Phoenix is a standalone ESP32-S3 hardware sampler designed as an instrument — not just a sample player.
Record, import, sculpt, loop, map, sequence and perform samples directly on the hardware, then manage complete banks comfortably on Windows with Phoenix Librarian.
Eight samples · four sequencer tracks · 12-voice engine · no DAW
Phoenix_Demo_Bank_01.mp4
Phoenix 3D printed case.
The current ESP32-S3 based hardware platform used for firmware, DSP and hardware development.
Project Phoenix is a complete sample-based musical instrument built around the ESP32-S3.
The sampler combines four directly accessible sample slots with a global 12-voice polyphonic playback engine, onboard recording, waveform editing, loop processing, multisamples, keyzones, MIDI, effects, a four-track pattern sequencer, song chaining, SD-card storage and USB mass-storage access.
Phoenix v1.0.0 FINAL is the first frozen stable release of the platform.
| Feature | Phoenix v1.0.2 |
|---|---|
| MCU | ESP32-S3 @ 240 MHz with PSRAM |
| Polyphony | 12 global sample voices |
| Audio engine | 32 kHz, 128-frame blocks |
| Basic sample slots | 4 |
| ADC | PCM1808 |
| DAC | PCM5102A |
| Sample import | WAV → Phoenix 32 kHz mono format |
| Sampling | Direct recording from ADC |
| Loop modes | OFF / FORWARD / ALTERNATE |
| Multisampling | Keygroups, velocity layers, round robin |
| Performance modes | KEYZONE / MULTI |
| Sequencer | 4 patterns × 4 tracks × up to 16 steps |
| MIDI clock | Internal / External, 24 PPQN |
| MIDI transport | FA Start / FC Stop, continuous F8 supported |
| Storage | SD card + USB Mass Storage |
| PC companion | Phoenix Librarian v1.0.0 |
Phoenix can record directly from the PCM1808 ADC and play back through a PCM5102A DAC.
Each sample can be edited directly on the hardware:
- Sample Start
- Loop Start
- Loop End
- Sample End
- Normalize
- DC correction
- Root note
- Pitch tracking
- ADSR
- Loop mode
- Loop crossfade
- Level and panorama
The four marker positions follow a clear playback model:
S.START ---- L.START ================= L.END ---- S.END
<---- LOOP AREA ---->
FORWARD loops restart at L.START.
ALTERNATE loops run as bidirectional ping-pong loops.
Phoenix uses one global voice pool for all sample slots and multisample regions.
┌─────────────────────┐
MIDI / Sequencer ──►│ 12-Voice Allocator │
└─────────┬───────────┘
│
┌────────────────┼────────────────┐
▼ ▼ ▼
Sample Voices Multisamples Keyzones
│ │ │
└────────────────┼────────────────┘
▼
Filter / FX / Mix
│
▼
PCM5102A
The v1.0 voice engine includes ownership protection, sustain handling, duplicate-note handling and guarded voice stealing.
Phoenix is not limited to four static WAV files.
The multisample system supports:
- multiple keygroups
- keyboard ranges
- velocity layers
- round robin
- root-note mapping
- one-shot regions
- forward loops
- alternate loops
- per-region sample assignment
This makes Phoenix suitable for much more than drums: pianos, strings, pads, percussion sets, sound effects and experimental sample instruments can all be built from the same engine.
The four primary sample slots can operate as a single performance setup.
Split the keyboard into zones and assign different samples to different ranges.
C1 C3 C5 C7
│------ SLOT 1 -----│
│------ SLOT 2 ------│
│------ SLOT 3 ------│
│------ SLOT 4 ------│
Several slots can respond simultaneously, each with its own level, panorama, range and processing.
This allows layered instruments, stacked textures and complex live setups.
One of the central architectural features of Phoenix v1.0.0 is the dedicated realtime sequencer path.
The final engine no longer lets display, SD-card or normal UI work determine musical timing.
CORE 0
┌────────────────────┐
│ MIDI Task P10 │
│ F8 / FA / FC │
└─────────┬──────────┘
│ timestamped clock
▼
┌────────────────────┐
│ SeqRT Task P8 │
│ 24 PPQN │
│ step scheduling │
└─────────┬──────────┘
│ scheduled events
══════════╪════════════════════════════════════
▼
CORE 1
┌────────────────────┐
│ Audio Task P24│
│ 128-frame blocks │
│ intra-block events │
└─────────┬──────────┘
▼
AUDIO
External MIDI clock is designed for systems where F8 continues permanently and transport is controlled separately by FA Start and FC Stop.
Six MIDI clock ticks correspond to one 16th-note sequencer step.
The v1.0 validation build demonstrated scheduled event placement inside the 128-frame audio block while keeping realtime audio overruns and clock/command drops at zero during the validated tests.
Phoenix includes a four-track hardware step sequencer:
- 4 patterns
- 4 tracks per pattern
- 1–16 steps per track
- note
- velocity
- gate length
- individual track lengths
- internal or external clock
- pattern management
- song chaining
A step contains:
ACTIVE | NOTE | VELOCITY | GATE
Different track lengths can be used to create polymetric patterns.
Phoenix v1.0 contains a lightweight realtime processing chain designed specifically for the ESP32-S3 audio budget.
Sample playback can be shaped using the onboard filter section with realtime cutoff and modulation control.
The delay engine includes smoothed parameter handling and click-reduced delay-time transitions.
Phoenix can deliberately move away from clean modern playback through its Vintage Sampler section, including reduced-rate / reduced-resolution style processing and character parameters.
Phoenix stores instruments as banks on the SD card.
Typical structure:
/PHOENIX
│
├── CONFIG.TXT
├── WAV/
├── EXPORT/
│
└── BANKS/
├── BANK01/
│ ├── BANK.CFG
│ ├── BANK.INFO
│ ├── SLOT1.WAV
│ ├── SLOT2.WAV
│ ├── SLOT3.WAV
│ ├── SLOT4.WAV
│ ├── MULTISAMPLE.CFG
│ ├── PATTERNS.CFG
│ └── SONG.CFG
│
├── BANK02/
└── ...
Current formats:
BANK_VERSION 15
MULTISAMPLE_VERSION 10
Phoenix uses transactional bank storage to reduce the risk of destroying an existing bank during a failed save operation.
Phoenix Librarian v1.0.0 is the Windows companion application for Project Phoenix.
It works directly with the same Phoenix bank structure used by the hardware.
- Bank management
- Waveform editor
- Loop editor
- KEYZONE / MULTI editor
- Pattern sequencer
- Song editor
- Echo / FX editing
- Bank metadata
- MIDI monitor
- On-screen keyboard
- Polyphonic PC audio preview
- Factory library
- Search and filters
- Backup & Restore
- Bank validation
- Self Test and diagnostics
PHOENIX HARDWARE
│
│ USB Mass Storage
▼
WINDOWS
│
▼
PHOENIX LIBRARIAN
│
├── Backup bank
├── Import / edit samples
├── Set loops
├── Build keyzones / multis
├── Edit patterns and songs
├── Preview audio
└── Validate
│
▼
Save to Phoenix volume
│
▼
Safely eject USB volume
│
▼
Reload bank on Phoenix
The Librarian can also work directly with the SD card or with a local copy of the complete Phoenix file structure.
Phoenix Librarian complements the hardware.
Phoenix plays the instrument — Librarian organizes, edits, previews and validates its data.
ESP32-S3 PCM1808 ADC
──────── ───────────
GPIO0 MCLK ─────────────► MCLK / SCKI
GPIO18 BCLK ─────────────► BCK
GPIO16 LRCK ─────────────► LRCK / WS
GPIO5 DIN ◄───────────── DOUT
ESP32-S3 PCM5102A DAC
──────── ────────────
GPIO18 BCLK ─────────────► BCK
GPIO16 LRCK ─────────────► LCK / LRCK
GPIO17 DOUT ─────────────► DIN
The PCM1808 and PCM5102A share BCLK and LRCK/WS.
The ADC master clock is supplied from GPIO0.
| Function | GPIO |
|---|---|
| PCM1808 MCLK / SCKI | 0 |
| I2S BCLK | 18 |
| I2S LRCK / WS | 16 |
| I2S DOUT → PCM5102A | 17 |
| I2S DIN ← PCM1808 | 5 |
| OLED SCK | 12 |
| OLED MOSI | 11 |
| OLED CS | 10 |
| OLED DC | 6 |
| OLED RESET | 7 |
| SD SCK | 12 |
| SD MOSI | 11 |
| SD MISO | 13 |
| SD CS | 9 |
| MIDI RX | 40 |
| MIDI TX | 39 |
| F1 | 21 |
| F2 | 47 |
| F3 | 45 |
| F4 | 38 |
| F5 | 4 |
| F6 | 15 |
| F7 | 3 |
| F8 | 14 |
| Encoder A | 1 |
| Encoder B | 2 |
| Encoder Switch | 42 |
| Native USB D− | 19 |
| Native USB D+ | 20 |
OLED and SD share SPI SCK GPIO12 and MOSI GPIO11, while using independent chip-select signals.
All GPIO signals are 3.3 V logic.
Phoenix deliberately separates realtime audio from MIDI, sequencing and user-interface work.
ESP32-S3 @ 240 MHz
CORE 1
└── AudioTask Priority 24
├── I2S input
├── voice rendering
├── sample-accurate scheduled events
├── filter / effects
└── I2S output
CORE 0
├── MidiTask Priority 10
├── SeqRT Priority 8
└── ControlTask Priority 3
├── UI
├── encoder / buttons
├── SD / bank management
└── system control
Audio block:
Sample rate : 32,000 Hz
Block size : 128 frames
Deadline : 4.0 ms
Voices : 12
Phoenix supports standard DIN MIDI through the ESP32-S3 hardware serial interface.
MIDI IN → GPIO40
MIDI OUT → GPIO39
Baud → 31250
The MIDI system supports, among other functions:
- Note On / Note Off
- Velocity
- Sustain pedal
- Pitch Bend
- Control Change
- MIDI Learn
- external MIDI clock
- Start / Stop transport
For external-clock operation:
F8 = MIDI CLOCK (24 PPQN)
FA = START
FC = STOP
Continuous F8 while stopped is explicitly supported.
Phoenix uses eight front-panel buttons and one rotary encoder with push switch.
F1 GPIO21
F2 GPIO47
F3 GPIO45
F4 GPIO38
F5 GPIO4
F6 GPIO15
F7 GPIO3
F8 GPIO14
Encoder A GPIO1
Encoder B GPIO2
Encoder SW GPIO42
The switches are active-low and are normally wired from GPIO to GND using the ESP32-S3 internal pull-ups.
The v1.0 FINAL firmware was developed for:
Arduino IDE 1.8.19
Arduino-ESP32 Core 2.0.16
MCU ESP32-S3
CPU 240 MHz
PSRAM 8 MB
Flash 16 MB
Audio 32 kHz / 128 frames
The realtime audio translation unit uses targeted optimization while avoiding global fast-math behavior.
- Build the Phoenix hardware according to the pinout above.
- Install the required Arduino libraries.
- Open the Phoenix v1.0.0 FINAL sketch in Arduino IDE 1.8.19.
- Select the correct ESP32-S3 board configuration.
- Compile and upload.
- Insert a prepared Phoenix SD card.
- Connect audio input/output.
- Connect MIDI.
- Power up Phoenix.
- Load a bank and play.
For detailed operation, see the Phoenix v1.0.0 Bedienungshandbuch in the repository documentation.
Hold the encoder switch while powering on Phoenix to enter the service/self-test area.
Available tests include:
- Audio Output Test
- Audio Input Test
- Button Test
- System Diagnostics
- Start Sampler
Runtime diagnostics expose audio, MIDI, sequencer and storage health counters, making realtime problems measurable instead of relying only on subjective testing.
The first stable Phoenix release was frozen after the v0.9.0 RC1 regression and endurance phase.
The validated release architecture includes:
- 12-voice realtime sample engine
- guarded MIDI / voice ownership
- transactional bank storage
- sample and loop boundary hardening
- robust MIDI Start / Stop handling
- continuous external F8 clock support
- dedicated realtime sequencer task
- intra-block event scheduling
- cooperative SD / bank I/O
- multisample validation
- stabilized delay-time changes
- USB Mass Storage workflow
- Phoenix Librarian integration
The v1.0 release is intended to remain frozen. Future development should branch from this release rather than modify the archived FINAL source.
docs/ ├── Phoenix_v1_0_0_Handbuch_DE.pdf
Phoenix started as a sampler experiment and grew into a complete embedded musical instrument.
The project explores how far an ESP32-S3 can be pushed when audio processing, MIDI, sequencing, storage and UI are treated as one coherent realtime system.
It is built around a simple idea:
Samples should not just be played back. They should become instruments.
Sample · Sculpt · Map · Sequence · Perform
ESP32-S3 Hardware Sampler
Phoenix v1.0.2 FINAL
RealTimeAudioLab / RTAL