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.