Senior Embedded Engineer; RTOS

The Opportunity

Lumai is redefining how the world computes. We are an ambitious, venture-backed UK startup pioneering a breakthrough AI accelerator for data centers which uses 3D optical compute. Our radical technology uses light to perform computation at orders of magnitude faster speeds and at far greater scales than ever before, all whilst consuming far less energy than traditional approaches.

Lumai is unlocking performance and efficiency gains that could transform the economics of AI and compute infrastructure and reshape how intelligence scales globally.

If you are passionate about bringing groundbreaking technology to market, and want to be part of a team pushing the boundaries of what is physically possible, Lumai is where you can make it happen.

Founded in 2022, Lumai is a University of Oxford spinout using optical processing to accelerate large language models (LLMs) and other transformer-based AI systems. The team combines expertise in optical computing, machine learning, and physics.

Lumai has already secured over $15 million in investment from leading deep-tech investors like Constructor Capital, IP Group, Photon Ventures and government grants, and is scaling rapidly to deploy the fastest optical compute currently available globally.

Lumai's hardware needs software that runs reliably at the lowest levels of the stack. As our Senior Embedded Engineer, you will build the firmware, drivers, and RTOS-based control software that bring our AI accelerator to life — from initial power-on through to stable, performant operation in production systems.

• Develop and maintain device drivers for Lumai's AI accelerator, targeting Linux kernel and bare-metal environments

• Write and debug firmware for control and management processors alongside the main accelerator die

• Lead BSP bring-up for new hardware revisions: clock tree configuration, interrupt routing, peripheral initialisation

• Implement RTOS-based control tasks using FreeRTOS or equivalent, ensuring deterministic scheduling and safe resource management

• Work with hardware engineers to validate bring-up through JTAG debugging, oscilloscope analysis, and logic capture

• Establish coding standards, review practices, and testing methodology for the embedded team

Must-Have

• 5+ years of embedded software experience with C/C++ in production hardware products

• Proven experience writing Linux device drivers (character, platform, or PCIe drivers)

• Hands-on BSP bring-up experience on custom hardware — from schematic review to first OS boot

• Solid understanding of RTOS concepts: task scheduling, inter-task communication, memory protection

• Proficiency with hardware debug tools: JTAG/SWD debuggers, oscilloscopes, logic analysers

• Bachelor's degree or higher in Electrical Engineering, Computer Engineering, or equivalent experience

Strong Preference For

• Experience with PCIe driver development or DMA engine programming

• Familiarity with power management frameworks (ACPI, Linux PM runtime)

• Prior work on AI accelerator or GPU driver development

• Highly Competitive Salary: We are not saying our salary is a blank check, but let's just say it won't be a source of your stress

• Share Option Scheme: We are all in this together! We believe in shared success while we build the Lumai of tomorrow

• Pension Scheme: Plan for retirement with AVIVA

• Private Health Insurance: We firmly believe that you come first, and a happy you is a healthy you! Look after yourself and your loved ones with AXA

• Cycle to Work: Spread the cost of a bike, a bike and accessories or just accessories and save on tax

• L&D Allowance: Stay at the forefront of your field with a £500 annual development budget

• Subsidised On-site Lunches: Enjoy on-site healthy meals at half the price, as Lumai covers 50% of the cost

• Holidays: Enjoy some deserved "me time" with 25 days paid holiday (plus bank holidays) per year

• Socials: Be part of an inclusive community enjoying occasional all-company off-sites, lunches and socials

Our process is four stages. An initial conversation with our HR team to understand what you want from the role and what we want from it. Two technical sessions with various members of our engineering team. Finally, an HR-team session covering scope, terms, and any final questions. We aim to move fast on candidates we are excited about; expect roughly three to four weeks end to end.

Lumai is an equal opportunity employer. We make hiring decisions on merit, scope-fit, and the strength of the working relationship we expect to build with each hire. Applications welcome from candidates of any background. If you are not sure whether you are a fit, send a note anyway.