Embedded Firmware Engineer

### Embedded Firmware Engineer ### Location ### Mexico (Remote) ### About the project We're building the next generation of a consumer health wearable for older adults. The device runs continuous biometrics, on-device interaction, and safety features, and syncs to a companion phone app over Bluetooth Low Energy. It's an in-flight firmware codebase on a Nordic nRF-family SoC built with Zephyr / the nRF Connect SDK; not a greenfield project. You'll own a defined slice of it and take it to production quality. The device connects over BLE (no cellular). Work is remote and async-first, driven from a Jira backlog and internal design docs. ### What you will do You'll own multiple workstreams end-to-end. Depending on fit and availability, that's a piece such as: * BLE connectivity and data sync: GATT services, connection lifecycle, pairing/bonding, and reliable delivery of event and bulk data to the phone. * A sensor or peripheral subsystem: driver bring-up and a clean capture/processing pipeline on constrained hardware. * Device interaction and state machines: buttons, haptics, indicators, and the flows that tie them together. * Power management: sleep/wake scheduling, duty-cycling, and hitting a multi-day battery target. * OTA and device robustness: dual-bank updates with rollback, safe against power loss. * Data integrity and secure storage: buffering, sync, and encryption of sensitive health data at rest. Every deliverable ships with tests and on-target validation evidence appropriate to a health device. ### Must-haves * **Nordic nRF-family firmware** experience, shipped to production. * **Zephyr RTOS / nRF Connect SDK** hands-on: device tree, Kconfig, and the west build system. * **BLE from the stack up:** GATT design, connection lifecycle, pairing/bonding, throughput, and fragmentation. * **OTA with rollback:** dual-bank updates that are safe at any point in the sequence. * **Power-constrained firmware:** you've hit a real battery-life target on a shipping product. * **Sensor/peripheral bring-up** straight from a datasheet (SPI/I2C/I2S), including interrupt- and DMA-driven data paths. * **Strong C**, comfortable in disassembly to chase interrupt, DMA, and timing bugs. * **A health-data quality bar:** you treat correctness and safety-critical paths as non-negotiable, and you're comfortable working with PHI/HIPAA-sensitive data responsibly. ### Nice-to-haves * Optical biosensor / PPG signal processing (HR, HRV, SpO2) and motion rejection. * IMU integration and on-device activity/motion classification. * Multi-core SoC firmware and inter-core communication. * Experience migrating or versioning a device-to-app data contract. ### How you work This is a low-direction, async-first engagement. We are hiring for the ability to turn that into finished, production-quality firmware with minimal supervision. Concretely, you: * **Turn vague asks into scoped work**: You write down what's in, what's out, acceptance criteria, and how you'll validate, before writing code. * **Ask the decision-relevant questions up front, then move**: You surface the two or three questions that actually change the design, rather than either stalling for a full spec or silently guessing on risky calls. * **Make and document reasonable assumptions** when an answer isn't available; pick a defensible default, note it, flag it, keep moving. * **Propose decisions with trade-offs**, not just questions. * **Surface risk and blockers early**, not at the deadline. * **Communicate in writing**: Design notes, clear PR descriptions with validation evidence, and a short decision log are the default. Expect to walk through a time you shipped something from a request; what you assumed, what you asked, and how you protected the deadline when reality diverged from the plan. Originally posted on [Himalayas](https://himalayas.app)