Firmware Engineer

ButterflyMX, Irvine Office/Warehouse

The role

At ButterflyMX, firmware sits at the critical intersection of electronics, embedded systems, product reliability, device security, and customer experience. We are seeking an exceptional Firmware Engineer to help design, build, debug, secure, and optimize the embedded software that powers our next generation of access control, intercom, IoT, wireless, and connected hardware products.

This role requires a rare combination of strong firmware development skill, deep hardware intuition, and practical embedded systems judgment. The successful candidate will be comfortable working close to the hardware — registers, buses, timing, interrupts, memory, power, analog behavior, digital interfaces, and real-world failure modes — while also understanding how embedded devices interact with secure cloud-connected systems.

What you will do

Develop Production-Ready Embedded Firmware
Design, write, debug, and maintain firmware across bare-metal, RTOS/Zephyr, and embedded Linux platforms.
Build reliable low-level firmware in C/C++ and other relevant firmware languages for microcontrollers, peripherals, sensors, communication interfaces, power systems, and device control logic.
Develop main-loop, interrupt-driven, event-driven, and multithreaded architectures optimized for timing, memory, latency, power, boot time, and long-term reliability.
Own firmware from board bring-up and prototype development through EVT/DVT/PVT, production release, and post-launch support.
Bridge Hardware, Firmware, and Real-World System Behavior
Work close to the hardware, including registers, buses, interrupts, ADCs, power rails, signal integrity, timing, noise, grounding, and analog/digital interactions.
Read schematics, understand PCB layouts, and collaborate with electrical and mechanical engineers on architecture, bring-up, manufacturability, thermal behavior, EMI/EMC, and field installation constraints.
Diagnose multi-domain failures using oscilloscopes, logic analyzers, debuggers, multimeters, power analyzers, and other lab tools.
Build firmware that is resilient to power instability, brownouts, signal noise, temperature extremes, communication faults, installation variability, and device aging.
Build Secure Connected IoT Device Firmware
Implement secure boot, bootloaders, chain of trust, signed firmware, certificate signing, key provisioning, device identity, and image validation.
Support secure OTA updates, rollback protection, version control, recovery behavior, and firmware authenticity.
Develop secure device-to-cloud and device-to-controller communication using appropriate authentication, cryptographic, and transport-layer protections.
Partner with security, cloud, and systems teams on device hardening, credential management, threat modeling, and secure manufacturing provisioning.
Implement Embedded Communication Protocols
Develop and debug firmware for I2C, SPI, UART, GPIO, ADC, PWM, RS-485, USB, Ethernet, BLE, Wi-Fi, and cellular-connected systems as applicable.
Implement reliable protocol handlers for access control, device-to-device, device-to-controller, and device-to-cloud communication.
Build robust error handling, retries, timeouts, diagnostics, telemetry, and graceful degradation into communication paths.
Create and maintain Interface Control Documents, protocol specifications, state diagrams, register maps, and integration documentation.
Drive Firmware Quality, Testability, and Reliability
Design firmware with observability, diagnostics, manufacturability, and field support in mind from the beginning.
Support built-in self-test, production test firmware, manufacturing diagnostics, burn-in, hardware validation, and release readiness workflows.
Develop unit tests, integration tests, hardware-in-the-loop tests, regression tests, and automated validation tools where appropriate.
Use disciplined engineering practices including code review, version control, CI/CD, static analysis, issue tracking, release notes, and root-cause documentation.
Partner with Quality, Support, Manufacturing, and Operations to analyze RMA trends, field failures, intermittent faults, and reliability issues.
Use AI Tools Responsibly to Increase Engineering Leverage
Use AI models and engineering tools to accelerate code development, debugging, test creation, documentation, and design exploration.
Independently validate AI-generated code, assumptions, and recommendations before using them in production systems.
Maintain full ability to write, review, debug, optimize, and explain firmware without relying on AI as a substitute for engineering judgment.
Solve Ambiguous Problems with Initiative and Tenacity
Approach problems holistically across electronics, firmware, mechanical constraints, manufacturing variation, installation conditions, cloud interaction, and customer impact.
Prototype quickly, test carefully, learn from data, and iterate toward robust production-ready designs.
Challenge assumptions, identify hidden failure modes, communicate tradeoffs clearly, and propose better architectures when the obvious path is not good enough.

What you need

5+ years of hands-on embedded firmware development experience; 8+ years is preferred for senior-level candidates.
Strong firmware development skills in C/C++, with experience writing production code for resource-constrained embedded systems.
Hands-on experience with bare-metal microcontroller firmware, RTOS-based systems, and embedded Linux. Experience with Zephyr is strongly preferred.
Strong understanding of microcontroller architecture, interrupts, timers, DMA, memory maps, bootloaders, watchdogs, peripheral drivers, low-power modes, and low-level register programming.
Deep practical understanding of electronics hardware, including digital and analog domains, power regulation, ADCs, signal conditioning, filtering, impedance, noise, grounding, and signal integrity.
Experience debugging real hardware using oscilloscopes, logic analyzers, debuggers, programmers, multimeters, and other lab equipment.
Experience with embedded communication interfaces such as I2C, SPI, UART, CAN, RS-485, USB, BLE, Wi-Fi, Ethernet, and cellular-connected systems.
Experience with secure boot, firmware signing, certificate signing, device identity, key provisioning, encrypted communications, and secure OTA update mechanisms.
Experience developing firmware for connected IoT products, ideally including products deployed in commercial, industrial, access control, building systems, consumer electronics, or field-installed environments.
Familiarity with higher-level communication patterns and protocols such as MQTT, REST, WebSockets, TLS, device-to-cloud APIs, and remote device management.
Ability to read schematics, understand PCB layouts, reason about hardware behavior, and collaborate effectively with electrical engineers.
Ability to troubleshoot multi-domain failures involving hardware, firmware, networking, environment, manufacturing, and customer installation factors.
Experience with Git, CI/CD, automated testing, static analysis, issue tracking, release management, and disciplined software development practices.
Strong documentation skills, including design notes, ICDs, state diagrams, test plans, debug guides, release notes, and technical decision records.
Strong initiative, tenacity, lateral thinking, and comfort operating in fast-moving product development environments.
AI-forward mindset with the engineering maturity to use AI tools as accelerants, not substitutes for deep technical understanding.

Firmware Engineer

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Firmware Engineer

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