Hardware
Reference Designs
Open schematics, bill of materials, PCB layouts, and build guides for sensor boards, controller modules, and display units.
These designs are research references for experimentation and learning. Any hardware built from these plans is not for diving use.
Platform Vision
A Fully Functional Electronic CCR
openCCR is designed from the ground up as a complete electronic closed circuit rebreather platform. The hardware spans three interconnected domains: custom electronics boards for oxygen sensing, loop control, depth measurement, and diver alerting; mechanical designs for the rebreather body, pressure housings, and breathing loop interfaces; and embedded firmware and a companion app to tie it all together into a coherent research platform. Every domain is fully open, documented, and designed to evolve independently as the community builds and refines it.
Repository — openccr/hardware
Electronic Design Files
Complete KiCad project for all openCCR boards. Schematics, BOM, Gerbers, and fabrication data in one repository. Licensed under CERN-OHL-S.
Schematics
Multi-sheet KiCad schematics covering all subsystems. Each sheet includes design-rationale annotations, net labels, and power-domain boundaries. Revision blocks track hardware versions across releases.
Bill of Materials
Fully annotated BOM with component values, tolerances, package types, and supplier part numbers for Digi-Key and Mouser. Includes BOM variants for different PO₂ cell connector types and regional availability.
Gerber & Fabrication Data
Gerber files, drill maps, and pick-and-place centroid data for each board. Design rules checked against JLCPCB and PCBWay specifications for cost-effective prototyping and small-run production.
PCB Designs
Platform Boards
Each board is a standalone module connected via rebus — the openCCR community's effort to define a standard CAN-bus-based communication layer for rebreather electronics. Unlike proprietary bus protocols, rebus is designed for interoperability: any vendor can build a board that speaks rebus and it will integrate with the rest of the system. Boards can be updated or replaced independently as the design evolves.
Controller Board
Main system brain. Built around the proven, low-energy nRF52 or nRF54 microcontroller family. Hosts power management circuitry, rebus master logic, USB and BLE interfaces for companion app connectivity, and on-board flash for dive log storage.
Sensor Conditioning Boards
Modular front-end boards available in multiple variants to accommodate different cell types. Variants support analog galvanic O₂ cells, digital solid-state O₂ cells, and CO₂ cells, in various combinations and channel counts.
Pressure Sensor Board
Measures ambient water pressure to determine current diving depth. Depth data feeds into the control loop for automatic setpoint changeover, decompression calculations, and dive log recording.
Solenoid Driver Boards
Driver boards for oxygen addition valves. Multiple variants support on/off solenoids and proportional valves and can include current-sense feedback for valve health monitoring and flyback protection.
HUD Boards
DSV-mounted multi-color LED array for PO₂ status, setpoint indication, and alarm signalling. Provides the diver with immediate glanceable feedback without requiring eyes-off interaction.
Display Boards
Full graphical displays in OLED, TFT, and e-Paper variants. Shows per-cell PO₂ readings, depth, decompression data, and active alarms in configurable layouts.
Alert Boards
Haptic and visual alerting modules for both diver and buddy notification. Wrist-mount, loop-mount, DSV-mount and standalone buddy-alert form factors planned.
Many More…
The rebus bus architecture is designed to be extensible. Future and community-developed boards can join the bus by implementing the rebus node specification — enabling new sensor types, display formats, alerting mechanisms, and integrations without modifying the core system.
Electronics · rebus Master
Controller Board
The brain of the openCCR system. Built around the Nordic nRF52, nRF53, and nRF54 microcontroller families, the controller board hosts all core system logic: power management, rebus bus master, Bluetooth Low Energy and USB connectivity for the companion app. It runs the primary firmware stack including PO₂ control loops, alarm management, and — optionally — onboard decompression algorithm execution.
Key Functions
- Nordic nRF52840 or nRF5340 MCU — ultra-low power with integrated BLE radio
- rebus bus master: arbitrates and coordinates all peripheral boards over CAN
- Regulated power supply rails for 3.3 V logic and 5 V bus; Li-ion battery monitoring and charging
- Bluetooth Low Energy for companion app connectivity: pairing, config, log export, OTA firmware updates
- Optional: USB interface for wired log transfer and firmware flashing during development
- Hardware watchdog: forces solenoid de-energisation on firmware hang or bus timeout
- Optional: onboard Bühlmann ZHL-16C decompression runtime with configurable GF settings
Schematic & Layout
KiCad schematic and PCB layout coming soon. Will include controller core, power management, and interface sub-sheets.
Electronics · Sensor Interface
Sensor Conditioning Boards
Modular front-end boards that interface directly with oxygen and CO₂ sensors. Available in multiple variants to accommodate the range of cell types and channel counts used in CCR designs. Each board handles signal conditioning, analog-to-digital conversion, cell health scoring, and broadcasts calibrated sensor readings to the controller board over rebus.
Variants & Functions
- Galvanic O₂ variant — high-gain transimpedance amplifier for multiple analog cells simultaneously; individual cell millivolt readout with low-noise ADC
- Digital O₂ variant — Digital interface for solid-state O₂ cells
- CO₂ variant — CO₂ sensor interface with temperature compensation for scrubber monitoring
- Continuous cell health scoring: drift detection, noise floor monitoring, and outlier flagging; degraded cells excluded from the voted PO₂
- Calibration constants stored in on-board EEPROM; written by the companion app, retained across power cycles
- Multiple cell connector options covering common O₂ cell body standards and thread types
Variant Design Files
Schematics for galvanic, digital, and CO₂ variants in design. BOM and Gerbers will be published per variant when ready.
Electronics · Depth
Pressure Sensor Board
Measures the ambient water pressure to determine the diver's current depth. Depth data is broadcast over rebus for use by the PO₂ control loop (setpoint changeover), the decompression algorithm, and dive log recording. The board also provides a calibrated water temperature reading for breathing loop thermal monitoring.
Key Functions
- Absolute ambient pressure sensor
- Temperature-compensated pressure readings; compensation coefficients stored on-board
- Depth calculation performed on the board; broadcast as calibrated depth in metres over rebus
- Secondary output: water temperature reading for loop thermal data
- Feeds automatic setpoint changeover logic: low setpoint on descent, high setpoint at bottom depth
- Depth and temperature written to every dive log sample record
- Pressure-rated housing interface: O-ring face-seal connector to electronics enclosure
Schematic & Layout
Pressure sensor interface schematic in early draft. Sensor selection and connector interface to be finalised based on depth rating requirements.
Electronics · Gas Addition
Solenoid Driver Boards
Controls the oxygen addition valve that maintains the breathing loop PO₂ setpoint. Receives actuation commands from the controller board over rebus and drives the solenoid via a protected high-side switch. Multiple variants cover standard on/off solenoids and proportional valves for precise gas flow control. Current-sense feedback provides valve health monitoring and fail-safe protection against stuck-open or stuck-closed faults.
Variants & Functions
- On/off variant — high-side MOSFET switch for standard normally-closed solenoid valves; suitable for most commercial O₂ addition valves
- Proportional variant — PWM-controlled driver for proportional solenoids enabling modulated gas flow; reduces loop PO₂ oscillation at setpoint
- Flyback diode and TVS protection for inductive load switching transients
- Inline current sensing: detects stalled, open-circuit, and short-circuit valve conditions
- Valve health status reported back over rebus and used to generate alarms
- Hardware interlock: solenoid de-energised on rebus communication timeout (independent watchdog)
- Configurable maximum injection duration limit as firmware-enforced safety ceiling
Driver Variant Files
On/off and proportional driver schematics under development. Valve connector type and housing interface to be defined alongside the mechanics repository.
Electronics · Diver Feedback
Head-Up Display Board
A DSV-mounted LED indicator module providing the diver with immediate, glanceable PO₂ status without requiring eyes-off-the-environment interaction. The HUD drives a multi-color LED array whose color and blink pattern encode the current PO₂ state, active setpoint, and active alarms. Receives display commands over rebus and operates independently of any full display board.
Key Functions
- Multi-color LED array; color encoding: green = PO₂ in range, yellow = caution, red = alarm condition
- Configurable brightness via rebus command; intended for adaptation to varying ambient light underwater
- PO₂ status indication: in-range, approaching high threshold, high, approaching low threshold, low
- Active setpoint indicator: slow blink pattern differentiates low vs high setpoint
- Alarm flash patterns per tier: advisory (slow), warning (medium), critical (rapid continuous)
- Compact PCB form factor for clip-mount attachment inside the diver's mask skirt
- Potted or conformal-coated for water immersion at depth
PCB Layout & Mechanical
Miniaturised PCB form factor under design. LED array placement and mask-mount bracket to be defined alongside the mechanics repository.
Electronics · Full Display
Display Boards
Full graphical display boards for detailed dive data. Designed to support multiple display technologies via swappable display modules, so the same carrier board can drive OLED, TFT color, or e-Paper panels depending on the build requirements. Shows per-cell PO₂ readings, voted PO₂ trend, depth, temperature, setpoint, decompression information, and active alarms in configurable screen layouts.
Variants & Functions
- OLED variant — high-contrast monochrome display; excellent visibility at depth; moderate power draw; suited to primary wrist or loop-mount units
- TFT color variant — full color for coded PO₂ trend graphs, per-cell comparison views, and decompression ceiling visualisation
- e-Paper variant — ultra-low power; updates between data changes only; suited for wrist-mount secondary display with infrequent reads
- Data received over rebus: voted PO₂, per-cell readings, depth, setpoint, active alarms, deco stops and ceilings
- Configurable display layouts: dive computer mode, PO₂ monitor mode, decompression mode
- Button or touch interface for layout switching depending on form factor
- Conformal-coated or encapsulated carrier board; display module behind flat pressure window
Display Variant Files
Carrier board schematic and per-variant display connector sub-sheets in design. Layout mockups will be published in the visual configurator.
Electronics · Alerting
Alert Boards
Alerting modules providing tactile and visual feedback for critical dive events, designed to catch the diver's attention even in high-workload situations.
Variants & Functions
- Wrist alert variant — haptic motor with tiered vibration patterns per alarm severity (advisory, warning, critical)
- Canister-mount strobe — high-intensity LED strobe visible to the buddy diver; waterproof and depth-rated
Form Factor & Schematics
Alert board variants in early concept stage. Haptic driver and strobe LED circuit design pending. Mechanical housing to be designed with partner organisations.
Repository — openccr/mechanics
Mechanical Design Files
STEP, STL, and 2D drawing files for all physical components of the openCCR platform. Designed for FDM/SLS 3D printing and CNC machining. Licensed under CERN-OHL-S.
3D CAD Models (STEP & STL)
Parametric STEP files for electronics pressure housing, sensor mounting pods, scrubber canister interfaces, and breathing loop connectors. STL exports for direct 3D printing.
2D Technical Drawings
DXF and PDF drawings with full GD&T annotations, O-ring groove specifications to AS568 standard, and machining tolerances. Each drawing includes a revision block and material callout (6061-T6 aluminium, Delrin, or PETG depending on application).
Pressure & Assembly Notes
Each enclosure design includes assembly notes with torque specifications, O-ring lubrication requirements, and an enclosure pressure-test procedure.
Tools
Plan Your Build Visually
Use the interactive configurator to drag and arrange openCCR boards and components, explore module combinations, and map out your build before you order any parts.