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Protoworks Prototype Building Blocks

Utility modules for rapid and reliable bench testing

Protoworks building block boards are practical engineering modules for embedded prototypes, test rigs, automation systems, and custom hardware projects. They provide reusable, tested circuits for common functions such as power entry, serial communication, protection, and digital I/O, reducing the need to rebuild the same support circuitry from scratch on every project.

These boards are not positioned as generic mass-market consumer products. They are working engineering tools, designed to be used directly on the bench or adapted into larger customer-specific designs.

The development process, design decisions, and bench-testing phase of some of these boards are documented in detail within the Field Notes section, which links directly to the founder's personal engineering journal at JKTDEV.CO.UK.

Need a prototype board adapted for your project?

These boards are available as starting points for custom embedded, automation, and hardware prototyping work. Small sample batches may also be available while designs are being validated.

Contact Protoworks

Overview & Approach

🔧 Development Focused

Through-hole headers and connectors are left unpopulated by default, giving you maximum flexibility in how you wire them into your project, prototype bench, or enclosure.

📡 4-Layer Layouts

Standardized around 4-layer PCBs to provide cleaner power and ground referencing, helping reduce avoidable layout-related noise during early testing.

📝 BOM Transparency

All Boards predominantly use readily available 0603/0805 components, while the self-assembly-focused Just Boards range uses larger footprints where practical. Fully open hardware under the CERN-OHL-W-2.0 licence, with KiCad project files and bills of materials.

🛡️ Basic Safeguards

Built with practical workbench protection features intended to reduce damage from common prototyping mistakes, such as brief shorts, transients, and some reverse-polarity wiring errors.

Just Boards Range

Bare PCB Utilities for Easy Home Assembly

The Just Boards range consists of unpopulated bare printed circuit boards, breakout adapters, and programming fixtures intended specifically for straightforward self-assembly at home or on the workbench.

These designs deliberately avoid microscopic assembly challenges by utilizing standard 2.54 mm through-hole components and accessible 1206-size SMT footprints (or SMT components of a similar size). This ensures they can be easily hand-soldered with basic soldering equipment using widely available components sourced affordably from mainstream retailers such as Amazon, AliExpress, and general electronic hobbyist suppliers.

Boards belonging to this series are tagged with the Just Boards badge across our hardware listings. Depending on demand and component availability, preassembled versions of selected boards may also be offered for those who prefer a ready-to-use option.

Current Board Status

Each prototype building block board is tracked with a status indicator to show its current phase in the hardware lifecycle, from initial planning and PCB design through fabrication, sampling, and eventual retirement.

StatusDescription
PlanningBoard is in the early planning stages before design.
In DesignBoard is currently being actively designed.
Awaiting FabricationBoards that are ready to be fabricated.
In FabricationBoards are currently being manufactured.
Available for SamplingSmall batches exist and may be available for customer feedback.
HaltedDesigns that are currently not prioritised or not economical to produce.
Retired / ReplacedEarlier designs are kept visible for transparency and development history.

Completed Boards

Hardware modules with manufactured units that are validated, bench-tested, and available for prototype sampling and project integration.

PowerBuilding Block Board

USB-C Power Input & 3.3 V Regulator Board

A simple power entry utility that combines USB-C power handling with a local 3.3 V regulated rail.

Status: Available for Sampling.
Follow development on www.jktdev.co.uk
USB-C Power Input & 3.3 V Regulator Board

Why This Board Exists

Saves you from repeatedly laying out power circuitry or relying on generic marketplace breakouts that can vary in quality, lack documentation, or omit basic circuit protection.

Circuit & Layout Details

  • Regulator: Based on the AP2114D-3.3 linear regulator (LDO) providing a stable 3.3 V output.
  • Input Protection: Includes a 500 mA hold / 1 A trip PPTC resettable fuse, an SMAJ5.0A TVS diode on VBUS for transient clamping, and an MBR130LSFT1G Schottky diode for basic backfeed protection.
  • Data Protection: Includes a USBLC6-2SC6 ESD protection array on the D+ and D− lines, which are broken out to pins for optional connection to external USB-to-UART converters.
  • Power Gating: Features a solder jumper to disconnect the power indicator LED when minimizing power budgets for low-power or battery-operated testing.
  • Interface: Standard 2.54 mm breakout pins for 5 V, 3.3 V, GND, D−, and D+, with dual M2 mounting holes for temporary bench installation.
CommunicationsCarrier Board

RS485 Isolated Carrier Board

An isolated differential serial carrier board providing galvanic isolation between host control systems and the RS485 communication bus, integrated with eFuse protection and a UCMOD MCU socket.

Status: Available for Sampling.
Follow development on www.jktdev.co.uk
RS485 Isolated Carrier Board

Why This Board Exists

Upgrades isolated serial communications for modular prototyping by introducing active eFuse protection, an updated isolated DC-DC power delivery stage, and an onboard UCMOD interface socket to directly host microcontroller plugin boards.

Circuit & Layout Details

  • Galvanic Isolation: Complete galvanic isolation between logic-side control circuitry and the RS485 differential bus lines to suppress ground loops and high-voltage transients.
  • UCMOD MCU Socket: Features a standardized UCMOD port allowing plugin microcontroller modules to dock directly onto the carrier board.
  • eFuse Protection: Integrated active eFuse protection to safeguard board circuitry against overcurrent and fault events.
  • Updated Isolated Power: Upgraded onboard isolated DC-DC converter for efficient power delivery to the bus-side transceiver.
  • Bus Configuration: Jumper-selectable 120 Ω bus termination and A/B bus biasing networks to maintain defined idle bus states.
  • Direction Control: Configurable jumper links for DE and /RE lines to manage half-duplex transmit and receive transitions from host GPIOs.
CommunicationsBuilding Block Board

RS485 Non-Isolated Breakout Board

A clean, non-isolated differential serial interface focusing purely on low-noise half-duplex communication for local or bench-scale networks.

Status: Available for Sampling.
Follow development on www.jktdev.co.uk
RS485 Non-Isolated Breakout Board

Why This Board Exists

Provides a simple, low-cost, and compact differential serial breakout for situations where all connected nodes share a common ground reference. Ideal for straightforward bench testing, short-distance cabinet wiring, or room-scale RS485 communication without the complexity of isolation or power distribution.

Circuit & Layout Details

  • Transceiver: Based on the 3.3 V MaxLinear SP3485EN differential transceiver.
  • Bus Configuration: Includes onboard jumper-selectable 120 Ω bus termination and selectable bus biasing using either stronger 470 Ω or weaker 4.7 kΩ resistors to establish the idle state of the bus.
  • Direction Control: DE and /RE lines are optionally linked via jumper to a single microcontroller GPIO to easily control half-duplex transmit/receive states.
  • ESD Protection: Features a dedicated TVS array to protect against electrostatic discharge (ESD) and transients on the differential bus lines.
IO ExpansionBuilding Block Board

Digital IO Expander Board

A deterministic, shift-register-based expansion module providing 16 logic-level inputs and 16 logic-level outputs.

Status: Available for Sampling (Minor Silkscreen Issue).
Follow development on www.jktdev.co.uk
Digital IO Expander Board

Why This Board Exists

Prevents microcontrollers from running out of GPIO pins on complex prototypes. Unlike I2C or SPI expander ICs, it relies on basic serial shift registers, avoiding address conflicts, complex software drivers, or bus lockups in noisy environments.

Circuit & Layout Details

  • Digital Inputs: Uses 2 x 74HC165 parallel-in, serial-out shift registers to read 16 logic-level input lines.
  • Digital Outputs: Uses 2 x 74HC595 serial-in, parallel-out shift registers to drive 16 logic-level output lines.
  • Connections: A centralized 12-pin header handles the microcontroller interface, while the 32 expanded digital I/O lines are broken out to physical screw terminals for reliable bench wiring.
MCU ModuleUCMOD

UCMOD-0 Microcontroller Module

An ATtiny1614-based pluggable microcontroller module featuring a UCMOD connector to provide microcontroller compute power to Protoworks carrier boards.

Status: Available for Sampling.
Follow development on www.jktdev.co.uk
UCMOD-0 Microcontroller Module

Why This Board Exists

Decouples microcontroller compute power from main baseboards. By plugging directly into the UCMOD header of a Protoworks carrier board, it provides compact, modular processing power while allowing easy MCU swapping and upgrading.

Circuit & Layout Details

  • Microcontroller Core: Powered by the Microchip ATtiny1614 8-bit AVR microcontroller (16 KB Flash, 2 KB SRAM).
  • UCMOD Connector: Integrated UCMOD connector designed to plug directly into the UCMOD socket of Protoworks carrier boards.
  • Programming Interface: Onboard Tag-Connect TC2030-IDC-NL footprint for fast UPDI programming and debugging.
  • Modular Design: Enables flexible compute integration across custom test rigs and carrier board setups.
Development ToolJust Boards

UPDI Friend to Tag-Connect Adapter Board

A compact adapter PCB (part of the Just Boards range) designed to connect an UPDI Friend programmer to a Tag-Connect TC2030-IDC-NL cable for flashing microcontrollers.

Status: Available for Sampling (Bare PCB - Just Boards Range).
Follow development on www.jktdev.co.uk
UPDI Friend to Tag Connect Board

Why This Board Exists

Provides a clean, direct interface to connect an UPDI Friend programmer to a Tag-Connect TC2030-IDC-NL cable, allowing quick and reliable programming of ATtiny 1614-based UCMOD-0 microcontroller plugin boards without breadboard jumper wires.

Circuit & Layout Details

  • UPDI Friend Interface: Standard 2.54 mm header footprint mapping UPDI data, power, and ground signals from the UPDI Friend programmer.
  • Tag-Connect TC2030 Footprint: Standard Tag-Connect TC2030-IDC-NL 6-pin footprint for spring-pin programming cables.
  • UCMOD-0 Target Compatibility: Optimized pinout routing designed to program ATtiny 1614-based UCMOD-0 microcontroller plugin boards.
  • Layout & Assembly: Compact 2-layer PCB routing with minimal component count using standard through-hole pin headers for fast bench assembly.

Awaiting / In Manufacturing

Completed board designs and bare PCBs currently awaiting fabrication or in production with manufacturing partners.

Development ToolCarrier BoardJust Boards

UCMOD Breakout Board PCB

A bench breakout board (part of the Just Boards range) designed to interface the UCMOD microcontroller module with standard 2.54 mm pitch headers for rapid breadboarding and testing.

Status: Awaiting Fabrication (Bare PCB - Just Boards Range).
Follow development on www.jktdev.co.uk
UCMOD Breakout Board PCB

Why This Board Exists

Enables quick bench evaluation and prototyping with UCMOD microcontroller modules without requiring a dedicated carrier board. It breaks out power, analog pins, and communication buses (I2C, SPI, UART) to standard breadboard-compatible 2.54 mm headers, and accepts power directly from modular power supplies like the USB-C Power Input & 3.3 V Regulator Board.

Circuit & Layout Details

  • UCMOD Socket: Dedicated 20-pin socket connector matching the standard UCMOD microcontroller module pinout.
  • Power Breakout Header: Dedicated power interface header allowing the breakout board to accept power directly from a modular power board (such as the USB-C Power Input & 3.3 V Regulator Board) or external bench supplies.
  • Standard Breadboard Headers: Dual 10-pin 2.54 mm pitch header footprints breaking out I2C (SCL/SDA), UART (TX/RX), SPI (MOSI/MISO/SCK/CS), analog inputs/DAC (AN0–AN3), and power rails.
  • Power Indication: Onboard footprint for a 1206 green power indicator LED with a 470 Ω current-limiting resistor on the 3.3 V rail.
  • Layout & Assembly: Designed on a 2-layer PCB utilizing standard 2.54 mm through-hole headers and larger 1206 SMT footprints for easy hand-soldering.
MCU ModuleUCMOD

UCMOD-L-STM32 Microcontroller Module

An STM32G0B1CBT6-based pluggable microcontroller module featuring integrated CAN peripheral support, a UCMOD connector, an auxiliary expansion connector, onboard QWIIC and OLED/I2C connectivity, and a Tag-Connect interface to deliver 32-bit ARM Cortex-M0+ processing power to Protoworks carrier boards (including the CAN Carrier Board).

Status: Awaiting Fabrication.
Follow development on www.jktdev.co.uk
UCMOD-L-STM32 Microcontroller Module

Why This Board Exists

Brings 32-bit ARM Cortex-M0+ compute performance, hardware CAN controller support, and expanded memory to the UCMOD ecosystem. It provides the processing capacity, dedicated auxiliary I/O breakouts, and CAN peripheral integration required to power advanced carrier boards like the CAN Carrier Board and RS485 Carrier Board while maintaining standard UCMOD interface compatibility.

Circuit & Layout Details

  • Microcontroller Core: Powered by the STMicroelectronics STM32G0B1CBT6 32-bit ARM Cortex-M0+ microcontroller (512 KB Flash, 144 KB RAM, operating up to 64 MHz) with integrated hardware CAN/FDCAN peripheral support.
  • UCMOD Connector: Integrated UCMOD connector designed to plug directly into the UCMOD socket of Protoworks carrier boards and breakout adapters.
  • Auxiliary Connector: Dedicated auxiliary expansion connector exposing additional microcontroller GPIOs, timers, and peripheral signals beyond the base UCMOD bus.
  • QWIIC Connector: Onboard 4-pin QWIIC connector (JST-SH 1.0 mm pitch) for plug-and-play daisy-chaining of external I2C sensors and accessories without soldering.
  • OLED / I2C Connector: Dedicated pin header for connecting standard 4-pin I2C OLED displays and external I2C expansion boards.
  • CAN Carrier Compatibility: Hardware CAN controller signals are routed to interface seamlessly with the Protoworks CAN Carrier Board.
  • Programming Interface: Onboard Tag-Connect TC2030-IDC-NL footprint for fast SWD (Serial Wire Debug) programming and real-time debugging.
  • Modular Compute: High-performance 32-bit MCU module for complex control routines, communications protocol handling, and real-time sensor processing.

Planned / In Design

New board designs currently in active planning, schematic development, and PCB layout stages.

MCU ModuleUCMOD

UCMOD-S-ATT Microcontroller Module

The successor to the original UCMOD-0 module, providing an updated revision of the ATtiny1614-based pluggable microcontroller board that incorporates programmer power isolation, reverse polarity protection for programmer power, and minor pin header adjustments for enhanced bench prototyping reliability.

Status: In Design.
Follow development on www.jktdev.co.uk
UCMOD-S-ATT Microcontroller Module

Why This Board Exists

Serving as the successor to UCMOD-0, it refines the modular 8-bit compute platform by protecting connected hardware during bench programming sessions. The addition of programmer power isolation and reverse polarity protection prevents back-powering carrier boards and eliminates voltage rail conflicts when flashing the ATtiny1614 on active assemblies.

Circuit & Layout Details

  • Microcontroller Core: Powered by the Microchip ATtiny1614 8-bit AVR microcontroller (16 KB Flash, 2 KB SRAM, up to 20 MHz).
  • Programmer Power Isolation: Provides power isolation circuitry on the programmer interface to prevent back-powering carrier boards and avoid power supply contention during flashing.
  • Reverse Polarity Protection: Integrated reverse polarity protection on the programmer power input to safeguard circuitry against accidental reversed wiring.
  • Pin Header Adjustment: Minor physical adjustments to the pin header layout for cleaner mechanical alignment and easier mating with carrier board sockets.
  • UCMOD Connector: Standard 20-pin UCMOD connector pinout designed to plug directly into the UCMOD socket of Protoworks carrier boards and breakout adapters.
  • Programming Interface: Tag-Connect TC2030-IDC-NL footprint for fast UPDI programming and debugging.
CommunicationsCarrier Board

RS485 Isolated Carrier Board Rev B

An updated revision of the isolated differential serial carrier board, refining active eFuse protection, isolated DC-DC power delivery, and UCMOD MCU docking for enhanced industrial prototype networking.

Status: Planning.
Follow development on www.jktdev.co.uk
RS485 Isolated Carrier Board Rev B

Why This Board Exists

Iterates on the RS485 Isolated Carrier Board architecture with updated PCB layout, enhanced transient protection, and optimized power stage routing while maintaining full galvanic isolation and seamless UCMOD microcontroller plugin integration.

Circuit & Layout Details

  • Galvanic Isolation: Galvanically isolates logic-side host and microcontroller circuitry from the differential RS485 bus lines to eliminate ground loops and prevent damage from high common-mode surges.
  • Isolated Power Delivery: High-efficiency onboard isolated DC-DC converter powering the bus-side transceiver circuitry.
  • eFuse & Transient Protection: Active eFuse circuitry with TVS transient suppression on differential lines for overcurrent, inrush, and ESD protection.
  • UCMOD Socket: Standard 20-pin UCMOD connector socket to directly host microcontroller modules (e.g. UCMOD-S-ATT, UCMOD-S-CH32, or UCMOD-L-STM32).
  • Bus Configuration: Jumper-selectable 120 Ω bus termination and biasing networks, with single-GPIO DE//RE direction control.
CommunicationsCarrier Board

CAN Carrier Board

An isolated Controller Area Network (CAN) carrier board designed to provide robust differential bus communication, equipped with galvanic isolation, active eFuse protection, ESD protection, and both the standard UCMOD Connector and Auxiliary UCMOD Connector for expanded microcontroller interfacing.

Status: Planning.
Follow development on www.jktdev.co.uk
CAN Carrier Board

Why This Board Exists

Extends the UCMOD modular hardware ecosystem with galvanically isolated Controller Area Network (CAN) bus connectivity, integrated active eFuse protection, and robust ESD suppression. It allows microcontroller plugin boards to interface safely and reliably with automotive, industrial, and distributed automation networks while routing additional signals through the Auxiliary UCMOD interface.

Circuit & Layout Details

  • Galvanic Isolation: Galvanically isolates logic-side microcontroller circuitry from the differential CAN bus to prevent ground loops and provide high-voltage transient protection.
  • UCMOD & Auxiliary Interface: Integrates both standard and auxiliary UCMOD socket interfaces for modular microcontroller plugins (the installed UCMOD MCU module must feature an integrated CAN bus peripheral).
  • CAN Bus Physical Layer: Transceiver circuitry designed for robust differential communications over noisy, multidrop environments.
  • eFuse Protection: Integrated active eFuse protection to safeguard board circuitry against overcurrent, inrush, and power fault events.
  • ESD Protection: Dedicated TVS diode array on the differential CAN bus lines to protect against electrostatic discharge (ESD) and line transients.
  • Bus Termination: Onboard jumper-selectable 120 Ω bus termination resistor.
CommunicationsCarrier Board

RS485 Non-Isolated Breakout Board Rev B

An updated revision of the clean non-isolated differential serial interface, featuring an added UCMOD socket for directly hosting pluggable microcontroller compute modules alongside standard bench breakout headers.

Status: Planning.
Follow development on www.jktdev.co.uk
RS485 Non-Isolated Breakout Board Rev B

Why This Board Exists

Builds on the proven simplicity of the original non-isolated RS485 breakout by introducing a dedicated UCMOD socket. This enables microcontroller modules (such as UCMOD-S-ATT, UCMOD-S-CH32, or UCMOD-L-STM32) to plug directly into the board, creating a compact, self-contained, low-cost communications node without requiring loose breadboard jumper wires.

Circuit & Layout Details

  • UCMOD Socket: Adds a standard 20-pin UCMOD socket interface to directly dock compatible microcontroller modules.
  • Transceiver: Based on the 3.3 V MaxLinear SP3485EN differential transceiver for low-noise half-duplex communication.
  • Bus Configuration: Includes onboard jumper-selectable 120 Ω bus termination and selectable bus biasing using either stronger 470 Ω or weaker 4.7 kΩ resistors to establish the idle state of the bus.
  • Direction Control: DE and /RE lines are optionally linked via jumper to a single microcontroller GPIO to easily control half-duplex transmit/receive states.
  • ESD Protection: Features a dedicated TVS array to protect against electrostatic discharge (ESD) and transients on the differential bus lines.
MCU ModuleUCMOD

UCMOD-S-CH32 Microcontroller Module

A compact, ultra-low-cost pluggable microcontroller module powered by the WCH CH32V006 32-bit RISC-V microcontroller, delivering high-efficiency 32-bit computing, integrated timers, ADC, and communication peripherals to the UCMOD ecosystem.

Status: Planning.
Follow development on www.jktdev.co.uk
UCMOD-S-CH32 Microcontroller Module

Why This Board Exists

Introduces open-standard 32-bit RISC-V compute performance at an ultra-low unit cost into the UCMOD modular standard. It provides an economical, power-efficient alternative for basic sensing, motor control, protocol bridging, and embedded automation tasks without sacrificing standard carrier board compatibility.

Circuit & Layout Details

  • Microcontroller Core: Powered by the WCH CH32V006 32-bit RISC-V microcontroller (QingKe 32-bit core, up to 48 MHz, 64 KB Flash, 8 KB SRAM).
  • UCMOD Connector: Standard 20-pin UCMOD connector pinout designed to plug directly into the UCMOD socket of Protoworks carrier boards and breakout adapters.
  • Peripherals & I/O: Exposes hardware UART, I2C, SPI, 12-bit ADC channels, and multi-channel timer/PWM outputs mapped to the standard UCMOD interface.
  • Single-Wire Debug: Onboard single-wire SDI interface footprint for rapid flashing, programming, and real-time debugging.
  • Cost-Optimized Architecture: Ultra-efficient BOM and minimalistic component footprint ideal for high-volume nodes and low-cost modular prototyping.
IO ExpansionCarrier Board

Digital IO Expander Board Rev B

An updated revision of the deterministic shift-register IO expansion module, adding an integrated UCMOD connector socket to directly host microcontroller modules and correcting a minor silkscreen labeling issue from Rev A.

Status: Planning.
Follow development on www.jktdev.co.uk
Digital IO Expander Board Rev B

Why This Board Exists

Builds on the proven deterministic shift-register architecture by incorporating a native UCMOD socket to directly host microcontroller plugin modules without loose wire interfacing, alongside corrected silkscreen pin markings for cleaner, error-free bench prototyping.

Circuit & Layout Details

  • UCMOD Socket: Integrates a standard 20-pin UCMOD socket interface to directly dock compatible microcontroller compute modules.
  • Silkscreen Revision: Corrects silkscreen pin labeling from Rev A for clear, precise pin identification on the bench.
  • Digital Inputs: Uses 2 x 74HC165 parallel-in, serial-out shift registers to read 16 logic-level input lines.
  • Digital Outputs: Uses 2 x 74HC595 serial-in, parallel-out shift registers to drive 16 logic-level output lines.
  • Connections: Centralized interface routing for UCMOD integration alongside physical screw terminals breaking out all 32 expanded digital I/O lines for reliable bench wiring.

📦 Retired & Halted Boards

Earlier design iterations, paused projects, and retired board revisions are maintained on a dedicated subpage for design transparency, hardware revision reference, and development history.

View Retired & Halted Boards →

Need a prototype board adapted for your project?

These boards are available as starting points for custom embedded, automation, and hardware prototyping work. Small sample batches may also be available while designs are being validated.

Contact Protoworks