Hardware

Firmware Engineer

Tokyo (Hatchobori)Full-time / Contract (negotiable)

About the Team

The hardware team at HAPT Lab takes electronic products from concept through to manufacturing in house — board design, firmware, mechanical design and the app. Because nothing is handed to an outside vendor, there is far less rework spent reconciling specifications, and decisions come quickly.

The products vary. In the golf device HAPT Golf, for instance, firmware turns what the sensors observe of a swing into what the actuators do. Human perception is remarkably sensitive to latency and inconsistency, and a few milliseconds decides the experience. That demand for real-time behaviour and repeatability sits at the technical centre of this team.

About the Role

You will define the architecture of our embedded systems and build it. That means owning the foundational decisions — boot, interrupt design, peripheral control, power management, wireless communication, and what happens when something goes wrong.

We are looking for someone who can move between two modes deliberately. Sometimes the right answer is an architecture reviewed carefully enough to last for years; sometimes it is a rough prototype working by the end of the afternoon so the team has something concrete to decide on tomorrow. Knowing which situation you are in matters more than being fast or being rigorous.

The work assumes hardware and an oscilloscope within arm's reach, so we expect you at our Hatchobori office and lab at least three days a week.

In this role, you will

Design the embedded architecture across boot, RTOS and scheduling, peripheral control, power management and wireless communication
Lead bring-up of new boards and find the path to getting them working
Design the real-time path from sensor input to actuator output, keeping latency and jitter inside their design targets
Design and review behaviour under failure — fault detection, watchdogs, and graceful degradation to a safe state
Build quick prototypes when learning matters most, then harden the ideas that prove out into production quality
Work alongside mechanical engineers and app developers from early prototype through to production
Establish testing across unit, hardware-in-the-loop, integration and fault-injection
Drive root-cause analysis on the hard-to-reproduce faults that live between hardware and firmware
Make tradeoffs across performance, memory, power, schedule and safety, and show the reasoning behind them

You might thrive in this role if you

Have developed embedded firmware for products that shipped, or for equipment that ran in real operation
Enjoy bringing up a new board and seeing it through until it works
Are fluent in low-level languages such as C, C++ or Rust, and comfortable close to the hardware under real-time constraints
Understand interrupts, scheduling, memory layout, buses, DMA, timing and failure modes from first principles
Can isolate problems at the hardware–software boundary with an oscilloscope and a logic analyser
Have instincts for defensive design, fault containment, and diagnosability after a device has shipped
Know when to build the durable system and when the fastest credible artifact unlocks the next decision
Communicate clearly across disciplines and can turn an ambiguous situation into a sound technical direction
Use AI-assisted tools such as Claude Code or Codex to accelerate implementation, debugging and prototyping

Nice to have

Embedded development in Rust, or with async embedded frameworks such as Embassy
ARM Cortex-M or Cortex-R platforms, RTOSes, and low-power embedded design
Working with wireless stacks such as BLE
Vibration actuators, motor control, or signal processing (filter design, FFT and similar)
Introducing Rust incrementally into an existing C/C++ codebase

Details

Employment type: Full-time / Contract (negotiable)
Location: Tokyo (Hatchobori)
Salary: JPY 7,000,000 – 12,000,000 (based on experience)
Working hours: Flexible hours (core hours 11:00–16:00)
Benefits: Social insurance, commuting allowance, budget for books and equipment, hybrid remote and on-site work

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