Embedded Software Engineer

Please note that we are unable to provide visa sponsorship for this position.

About Proper Voltage

Proper Voltage is unlocking the next generation of battery technology across robotics, data centers, and defense.

We're building intelligent battery systems that make advanced chemistries (sodium-ion, lithium-titanate, lithium-silicon) work in products that were never designed for them. Humanoid robots can upgrade power systems without redesigning their entire platform. Data centers get safer, cheaper backup power. Drones and autonomous vehicles get higher energy density without lengthy integration cycles.

If you want to work on hard engineering problems that matter this is the place.

Job Overview

We are looking for an Embedded Software Engineer who is passionate about writing firmware that runs on real hardware in safety-critical environments. In this role, you will develop and maintain firmware for our battery management systems running on STM
32 microcontrollers, implementing core BMS functions including cell monitoring, protection algorithms, communication protocols, and sensor interfaces. You’ll work closely with hardware and senior firmware engineers to bring up new boards, integrate analog front ends, and ship production-quality firmware across multiple battery chemistries. This is a hands-on individual contributor role within a fast-moving, multi-disciplinary engineering team.

What You’ll Do

• Develop and maintain BMS firmware on STM
32 platforms (Cortex-M33/M4) in C, targeting safety-critical battery applications across sodium-ion, lithium-titanate, and lithium-ion chemistries.

• Implement and test peripheral drivers for ADC, SPI, I2C, UART, CAN, DMA, and timers as part of the BMS firmware platform.

• Develop firmware for cell voltage and temperature monitoring, over/under-voltage and over-current protection, and thermal management.

• Implement and tune passive cell balancing algorithms for multi-series pack configurations.

• Integrate and validate analog front-end interfaces, including isolated amplifiers (AMC
1301), current sense circuits, and voltage divider chains.

• Develop CAN bus communication firmware for BMS-to-host data exchange, status reporting, and command interfaces.

• Write, execute, and maintain unit tests and hardware-in-the-loop tests to validate firmware functionality and fault response.

• Support board bring-up activities: verify power rails, validate peripheral communication, and debug hardware/firmware integration issues.

• Collaborate with hardware engineers on schematic review and provide firmware-side input on signal routing, filtering, and component selection.

• Contribute to firmware documentation including design descriptions, interface specifications, and test procedures.

• Support safety compliance efforts by implementing firmware requirements derived from FMEA and fault tree analysis for UL 1973 certification.

• Participate in code reviews and contribute to continuous improvement of firmware development practices.

• Ability to either work in person at our Carlsbad, CA office or travel there as needed with a demonstrated track record of highly efficient, collaborative remote work.

Required Qualifications

• B.S. or M.S. in Computer Engineering, Electrical Engineering, Computer Science, or related field.

• 3+ years of experience developing embedded firmware in C for ARM Cortex-M microcontrollers.

• Hands-on experience with STM
32 peripherals: ADC, SPI, I2C, UART, CAN, DMA, and GPIO.

• Experience with RTOS-based firmware development (FreeRTOS, Zephyr, or equivalent).

• Familiarity with embedded debugging tools and workflows (JTAG/SWD, logic analyzers, oscilloscopes).

• Understanding of analog signal chains as they relate to firmware: ADC sampling, filtering, calibration, and noise management.

• Experience with CAN bus communication protocols and message framing.

• Proficiency with version control (Git) and structured development workflows.

• Ability to read and interpret hardware schematics, datasheets, and reference manuals.

• Effective communication skills across various levels of the organization.

• Proven ability to multitask and thrive in a fast-paced startup environment, with minimal…