Pandore

Pandore

Open-source digital audio instrument prototyping platform.

Pandore is a custom-designed PCB built around the LattePanda Mu compute module, a Teensy 4.1 audio bridge, dual RP2350 microcontrollers, and a professional audio I/O chain. It provides a complete hardware foundation for building digital audio instruments, effects processors, and experimental sound tools.

Status

Revision A0 — PCBA complete at PCBWay (3 units); hand-assembly of the through-hole/DNP parts and board bring-up in progress. Manufacturing files released 2026-03-19; DRC passing. See the interactive BOM and the A0 bring-up / hand-assembly guide.

PCBWay substitution: RP2350A was unavailable at assembly time; PCBWay substituted RP2350B (QFN-80) for both MCU positions. RP2350A and RP2350B are binary-compatible — same cores, same peripherals, same memory map — they differ only in package size and number of exposed GPIO pins (30 vs 48). Firmware developed on RP2350A Pico boards transfers without modification.

Board Specifications

Architecture

                         +-----------------+
                         |  LattePanda Mu  |
                         |  (x86-64 SBC)   |
                         +--------+--------+
                                  |
          +----------+-----------+-----------+----------+
          |          |                       |          |
 +--------+-------+  |             +---------+--------+ |
 |  RTIO MCU      |  |             |  Management MCU  | |
 |  (RP2350)      |  |             |  (RP2350)        | |
 +--------+-------+  |             +---------+--------+ |
          |          |                       |          |
 +--------+-------+  |             +---------+--------+ |
 | UART, SPI, I2C |  |             | GPIO, Power Seq, | |
 | ADC, 8x PWM    |  |             | Fan, Display     | |
 +----------------+  |             +------------------+ |
                     |                                  |
            +--------+--------+                         |
            |   Teensy 4.1    |                         |
            | (I2S-to-USB     |                         |
            |  Audio Bridge)  |                         |
            +--------+--------+                         |
                     |                                  |
            +--------+--------+               +---------+--------+

Compute

• LattePanda Mu — x86-64 SBC (Intel N100 or N305), main application processor. Recommended: DFR1147 (N100, 16 GB LPDDR5) — the N305 gives only ~13% single-core gain at ~2× cost, with no meaningful benefit for real-time audio workloads where single-thread performance dominates.
• RTIO MCU (RP2350) — Real-time I/O: UART, SPI, I2C, USB, ADC, 8x PWM channels
• Management MCU (RP2350) — System control: power sequencing, GPIO, fan, display, boot

Audio

• Audio/MIDI bridge: Teensy 4.1 — I2S-to-USB audio bridge between the CS4272 codec and the LattePanda Mu, also handles MIDI data transfer to the host computer
• Codec: Cirrus Logic CS4272 — stereo 24-bit ADC/DAC, I2S interface
• Preamp: THS4521 fully-differential amplifier + OPA1656 op-amp signal conditioning
• Phantom power: 48V supply via TI LM5158 flyback controller + TPS7A4001 ultra-low-noise 40V LDO post-regulation (~10 mA) for condenser microphones
• I2S isolation: TI ISO7762FDBQR — 6-channel digital isolator (4 forward / 2 reverse), 100 Mbps, 5000 VRMS galvanic isolation between digital and audio domains
• I2C isolation: TI ISO1640BDR — isolated I2C for codec control path, 2500 VRMS isolation
• Isolated power: Murata NXE2S1212MC-R7 — 2W isolated 12V→12V DC/DC converter (167 mA) for the isolated audio domain
• MIDI isolation: Isocom H11L1SMT optoisolator with Schmitt-trigger output on MIDI IN
• Monitor output: Dedicated headphone/speaker amplifier with hardware volume knob (Bourns PTR902-2020K-A103 — 10 kΩ audio taper, 20 mm shaft)
• Input buffering: Balanced input stage with line/mic switching
• Output buffering: Line-level outputs

Power

Power ICs:

• Reverse-polarity, overcurrent, and overvoltage protection
• USB VBUS overcurrent handled by the ET20162 load switches (1A fixed limit each)
• PTC fuses (Bel Fuse 0ZCM0010FF2G, 0.1A) protect the Grove ports (J17/J18) on the standby rail
• Managed power-on sequencing via Management MCU

Connectivity

• Ethernet — 2× Gigabit Ethernet via Realtek RTL8111H-CG PCIe controllers (U7, U8), 2× shielded RJ45 with isolation transformers (Würth 749020111A)
• USB — 4× USB-A ports (2× USB 3.0 via J3 + 2× USB 2.0 via J2) broken out from the LattePanda Mu's 8 USB lanes (remaining lanes are internal — Teensy audio bridge, AX210 WiFi/BT); plus the Teensy 4.1's own USB-C jack exposed at the back panel
• MIDI — 5-pin DIN IN/OUT with H11L1 optoisolation
• Display — 24-pin 0.5mm FPC ZIF connector (GCT FFC2A32-24-T) for OLED status display (SSD1309, 128×64 px, 1.54") — see Components Requiring Separate Assembly
• M.2 Key-M — PCIe x4 (NVMe SSD)
• M.2 Key-A+E — WiFi/Bluetooth (tested: Intel AX210 — WiFi 6E tri-band + BT 5.3) or alternate storage
• Expansion headers — GPIO, analog, I/O breakouts; 2× Grove I2C connectors (3.3V, use Qwiic / STEMMA QT sensors — see below); I2S header; UART debug

User Interface

• Encoder: Bourns PEL12T-4225T-S1024 — 24 PPR optical rotary encoder with momentary push switch and RGB LED illumination
• Tactile switches: 4× C&K PTS810 momentary switches (B1–B4)
• Volume knob: Bourns PTR902-2020K-A103 potentiometer — 10 kΩ audio taper, 20 mm shaft (monitor output level; replaces BOM part 2015K-B103, linear, 15 mm)
• RGBA LED: AMS-OSRAM multi-colour LEDs — blue (×3), green (×4), orange (×7), red (×1) status/indicator outputs

Sensors

• BMI270 — 6-axis IMU (accelerometer + gyroscope) for motion-based control

External sensor expansion (Grove ports)

The two Grove connectors (J17/J18) are I2C sensor ports running at 3.3V — each on its own management-MCU I2C bus (J17 = I2C0, J18 = I2C1), powered from the standby rail through a 0.1A PTC fuse.

Because the ports are 3.3V, use the Qwiic / STEMMA QT sensor ecosystem (SparkFun, Adafruit, Arduino Modulino) — it is 3.3V-native, so modules plug in safely with no level shifting. A standard Grove-to-Qwiic adapter cable (Adafruit #4528 or SparkFun PRT-15109) connects them. Note: M5Stack Units are powered at 5V and are not directly compatible.

Flash Storage

3× Winbond W25Q128JVSIM (128 Mbit / 16 MB, QSPI):

• U2 — BIOS flash (LattePanda Mu)
• U5 — RTIO MCU flash (RP2350, U3)
• U6 — Management MCU flash (RP2350, U4)

Thermal

• 2× 4-pin PWM fan headers (J27 CPU, J38 system), Molex KK 254 47053-1000
• Fan header pinout: 1=GND, 2=5V, 3=Tach, 4=PWM (fed directly from the 5V rail — note: 5V, not the 12V of a standard PC fan header)
• PWM-controlled fan driver circuit
• Three heatsink options: active cooler (DFRobot FIT0981, 5V fan), thin passive, fanless

Audio Performance

See Audio Performance for the full signal chain, component specs, system-level estimates, physical I/O, and performance class.

Highlights: 24-bit / 192 kHz, 114 dB dynamic range, -100 dB THD+N, 5000 VRMS galvanic isolation, 2× Neutrik combo XLR+TRS inputs with 48V phantom power.

Repository Structure

pandore/
  hw/               Schematics (.kicad_sch) and PCB layout (.kicad_pcb)
  doc/
    arch/           Architecture diagrams (draw.io)
    img/            Board renders
    reference/      Datasheets, app notes, design guides (PDF)
  lib/              3D models (.step), KiCad symbols and footprints
  release/          Manufacturing artifacts (Gerbers, BOM, placement, 3D)

Schematic Hierarchy

The top-level schematic (pandore.kicad_sch) references 24 sub-sheets organized by subsystem:

Audio — audio, audio-codec, audio-inputs, audio-inbuf, audio-outputs, audio-outbuf, audio-isolation, audio-monitor, audio-power

Compute — computer, cpumod, mcu, mgmtmcu, rtmcu

Power — power, audio-power

Interface — eth, usbport, midi, display, extraport, mdot2

System — bootctl, bios, fan

Components Requiring Separate Assembly

The PCBWay PCBA order covers all SMD components. The following through-hole and DNP parts must be sourced and hand-soldered separately. BOM part numbers are listed; substitutions are noted where a different part is recommended over the original BOM.

Manufacturing

The release/ directory contains two packages dated 2026-03-19 (revision A0):

• pandore_*_A0_pcba.zip — PCBA package: Gerbers, drill files, BOM (.csv), pick-and-place (.pos)
• pandore_*_A0_release.zip — Full release: PCBA files + 3D assembly model (.step), assembly drawings (PDF), rendered board images, ERC/DRC reports

4-layer stackup. 2,439 drill holes. All components have manufacturer part numbers assigned.

Reference Documentation

The doc/reference/ directory includes datasheets and design guides used during development:

• RP2350 datasheet and hardware design guide
• LattePanda Mu evaluation kit guide and carrier board reference
• CS4272 codec (via SuperAudioBoard design guide and schematic)
• THAT1512 microphone preamp gain configuration (reference design)
• 48V phantom power supply design (TI SBOA320A + ultra-low-noise RAQ approach)
• Analog circuit design references (Analog Secrets series, AES mic preamp paper)
• THAT Corporation mic preamp reference design (git submodule)

Requirements

• KiCad 10 to open and edit schematics and PCB layout
• draw.io to view architecture diagrams

Credits

Designed by Vincent Fillion at Artificiel, with the help of Alexandre Burton.

Hardware engineering and KiCad source files by Laurence Deschênes Villeneuve (@laurencedv).

License

This project is licensed under the CERN Open Hardware Licence Version 2 — Strongly Reciprocal (CERN-OHL-S-2.0).

You are free to use, study, modify, and distribute this design, provided that:

• You credit the original authors
• You distribute any modified versions under the same licence
• You make the source files available