Embedded Firmware Engineer (Wearables)

Rajant Health; Malvern (Chester County); On-site; USD 110,000 - 140,000; Full time

Job summary

Rajant Health is seeking a firmware-first embedded systems engineer to develop low-power wearable and connected products from bring-up to production and field support.

The role emphasizes hands-on embedded engineering, signal-processing validation, and hardware-software integration, with a track record of delivering real product impact.

Qualifications

• Strong embedded C skills and practical hardware experience.
• Mastery of Cortex-M class MCUs and RTOS or strong bare-metal fundamentals.
• Experience bringing up and debugging custom embedded hardware.
• B.S./M.S. in Electrical/Computer Engineering or related field, or equivalent.

Responsibilities

• Design, implement, and maintain production-quality firmware for Cortex-M MCUs with an RTOS.
• Own embedded features end to end, including drivers, interrupts, DMA, and validation.
• Bring up custom boards, debug boot behavior, power rails, sensors, and radios.
• Build sensor-acquisition pipelines with sampling, timing, and calibration.
• Translate Python/MATLAB algorithms to embedded C/C++ and validate them.
• Characterize and optimize real-system power consumption and wake-sleep cycles.
• Integrate and debug BLE/Wi‑Fi connectivity and data transport.
• Develop manufacturing-test firmware and host-side automation.
• Collaborate across electrical, mechanical, DSP, and product teams.

Skills

Embedded C

RTOS

Power optimization

Sensor integration

Python

Debugging hardware

DSP basics

Cortex-M

Education

B.S./M.S. in EE/CE/CS

Tools

JTAG/SWD

Zephyr

Nordic

Ambiq

Job description

We are seeking a firmware-first embedded systems engineer to develop low-power wearable and connected products from initial bring-up to production and field support. You are a fit if you get useful things working quickly, test them against reality, and incessantly improve them without getting attached to your first approach.

The center of gravity for this role is hands-on embedded engineering work: developing reliable C firmware, bringing up custom hardware, integrating sensors and radios, measuring and optimizing power, implementing and validating signal-processing algorithms, building test infrastructure, and system-level debugging and problem-solving. You will also contribute to biosensing approaches, real-time control systems, and AI-assisted hardware development infrastructure.

We care more about the quality and depth of your work than a particular number of years or a job title. This role is a natural fit for an experienced engineer with an extensive catalog of solved problems, shipped features and quantified product improvements. It can also fit an early-career engineer with an excellent track record, sound fundamentals, high learning velocity, and evidence of real product impact.

What you'll do

• Design, implement, and maintain production-quality firmware for Cortex-M-class MCUs and SoCs using an RTOS and, where appropriate, bare-metal components
• Own embedded features end to end, including architecture, device drivers, interrupts, DMA, task and event interactions, timing, state machines, error recovery, diagnostics, and validation
• Bring up custom boards and new hardware revisions. Debug clocks, reset and boot behavior, pin configuration, power rails, sensors, external memory, buses, and radio interfaces using schematics, datasheets, JTAG/SWD, oscilloscopes, logic analyzers, and power analysis tools
• Participate in schematic and layout reviews, with particular attention to firmware integration, boot and programming paths, power control, signal integrity, test points, diagnosability, and design for manufacturing and test
• Build robust sensor-acquisition pipelines, including sampling, timestamping, synchronization, buffering, calibration, filtering, feature extraction, and signal-quality monitoring
• Translate and validate appropriate Python or MATLAB reference algorithms in embedded C/C++, making evidence-based choices about numeric precision, memory, latency, computational cost
• Characterize and improve real system power consumption through measured power budgets, sleep and wake-state design, peripheral and rail control, sensor duty cycling, radio scheduling, and investigation of leakage or unexpected wakeups
• Integrate and debug low-power wireless connectivity such as BLE and Wi-Fi, including provisioning, data transport, coexistence, connection recovery, throughput, and power behavior
• Help move products into production by developing manufacturing-test firmware, host-side automation, fixture and test-jig interfaces, calibration and provisioning flows, traceability, and useful failure diagnostics
• Build automated unit, integration, bench, fault-injection, and hardware-in-the-loop tests. Turn difficult bugs and field failures into reproducible regressions
• Work closely with electrical, mechanical, DSP, application, manufacturing, and product engineers, and document technical decisions clearly enough for others to build on them

Requirements

• Strong embedded C skills, practical hardware experience
• Mastery of at least one resource-constrained MCU (Cortex-M class), and a solid understanding of memory, timing, interrupts, DMA, concurrency, and real-time behavior
• Experience with an RTOS, or sufficiently strong bare-metal fundamentals to learn one quickly
• Experience bringing up and debugging custom embedded hardware
• Ability to read schematics and component datasheets and reason across firmware and hardware boundaries
• Practical experience with common board protocols (SPI, I2C, UART, I2S) and peripherals (timer, watchdog, display, IMU, touch, haptics, AFE)
• A measurement-driven approach to debugging and power optimization using DMM, logic analyzer, oscilloscope, power analyzer, other lab instruments
• Python proficiency for test automation, data analysis, device control, manufacturing tools, algorithm verification
• Working knowledge of sampling, aliasing, digital filtering, noise, calibration, numerical precision, and basic time- and frequency-domain analysis
• Experience taking an embedded system beyond initial prototype- through structured validation, pilot, deployment, manufacturing, field support, or other customer-facing use
• Strong engineering judgment, curiosity, ownership, and the ability to learn unfamiliar hardware or technical domains quickly
• A B.S. or M.S. in Electrical Engineering, Computer Engineering, Computer Science, or a related field, or equivalent practical experience

Additional experience - a strong plus

• Biosensing and optical systems (PPG)
• Real-time sensing and controls
• Power optimization, ultra-low-power wearables
• Design for manufacturing, test jig design
• Digital or mixed-signal board design, ownership of schematic or PCB layout reviews
• Development of safety-related or high-reliability embedded systems
• Zephyr, Nordic, Ambiq

We expect many successful candidates will have approximately two or more years of relevant hands-on experience, but there is intentionally not a rigid seniority filter. Two years of substantive product work - with increasing product ownership, strong debugging ability, clear technical growth, and excellent references or work samples - can be enough.

Overall, we are looking for strong firmware fundamentals, demonstrated excellence and potential, and a record of learning hard things. Specialized experience in biosensing, controls, RF, power optimization, or manufacturing can differentiate a candidate, but no single candidate is expected to be an expert in all of them.