Senior Software Engineer (Embedded/Mobile) — BLE + NFC Data Transfer

Part-time (ongoing) · Remote — anywhere

Summary

The client seeks a senior engineer to take ownership of a critical device-to-app data transfer layer and bring it fully in-house. The software is already built and in use, but current changes depend on a third party. The role involves leading a project to design, implement, and document an internal solution—de-risking the client’s kit and enabling faster iteration. A core focus is a Bluetooth Low Energy (BLE) GATT service used to transfer “receipt” payloads larger than 8 KB after an NFC handshake.

Key Responsibilities

• Own the in-house implementation of the device ↔ app data transfer layer, replacing or replicating third-party behavior as needed.
• Specify and build a custom BLE GATT service with two characteristics (write, read) and notifications for new data availability; design the end-to-end state machine.
• Implement the NFC → BLE handoff: parse NFC headers containing the BLE endpoint address and file size; orchestrate secure, reliable switch to BLE for large payloads (>8 KB).
• Throughput & reliability: chunking/segmentation & reassembly, MTU tuning, flow control, retry/CRC, resume on disconnect, and back-pressure handling.
• Security & pairing: authenticated pairing/bonding, encryption, and key handling appropriate to the platform.
• Build the client-side SDK(s) for mobile and/or embedded integration (iOS/Android app layer and/or device firmware) with clean APIs and clear documentation.
• Testing & tooling: create a test harness/simulator, packet capture workflows, and automated integration tests; instrument logs and metrics.
• Knowledge transfer: document architecture, protocols, and operational runbooks; enable the client’s team to maintain and evolve the solution.

Required Experience

• 7+ years professional software engineering, including leadership/ownership of production deliverables.
• Deep expertise with Bluetooth Low Energy (BLE): GATT, characteristics, notifications/indications, MTU/connection interval tuning, and large-payload strategies.
• Hands-on with NFC (NDEF/TLV, header parsing, device handoff patterns).
• Proficiency in at least two of the following:
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  • Embedded: C/C++ or Rust; Zephyr/FreeRTOS; experience with common BLE chipsets (e.g., Nordic, ESP32, Silicon Labs).
  • Mobile: iOS (CoreBluetooth, Swift/Obj-C) and/or Android (Kotlin/Java BLE); building robust BLE client libraries/SDKs.
• Strong debugging with protocol analyzers/sniffers, and building reliable state machines across unreliable links.
• Excellent documentation and communication skills; comfortable driving an in-house build from ambiguous starting points.

Nice to Have

• Experience in payments/receipts or regulated device environments.
• L2CAP CoC familiarity, background transfers, and cross-platform SDK design.
• Security best practices for BLE/NFC (pairing modes, key storage).
• Familiarity with CI/CD for firmware/app builds and over-the-air update flows.

Engagement Details

• Type: Contract, part-time (ongoing).
• Hours: Flexible; propose availability.
• Start: ASAP.
• Location: Remote — anywhere (full location flexibility).
• Compensation: Market-competitive; open to discussion.

Success in the First 90 Days

• Reverse-engineer/document the current third-party behavior and constraints.
• Ship a working in-house BLE+NFC transfer path for >8 KB payloads with tests and metrics.
• Deliver a client library/SDK (and/or firmware module) with clear API and integration docs.
• Establish a test harness and automated checks (incl. packet capture workflows).

About the Client (anonymized)

The client ships a connected device in production and currently relies on a third party for key software changes. They are de-risking their platform by bringing core device–app data transfer capabilities in-house to improve reliability, velocity, and IP control.

Interview Process (proposed)

1. Intro call with Tribes (30 min) — background and scope.
2. Technical deep dive (60–90 min) — BLE/NFC architecture walkthrough and past work; whiteboard or live code review (no take-home unless requested).
3. Final conversation with stakeholders — alignment on scope, hours, and start.

How to Apply

Share your CV/LinkedIn, relevant GitHub/work samples, and a brief note on your BLE/NFC projects. Please include availability (hours/week) and day-rate/salary expectations. Applications via Tribes only.

Tribes’ Commitment to DEI

Tribes is committed to diversity, equity, and inclusion. We welcome candidates of all backgrounds and do not discriminate based on race, color, religion, gender identity or expression, sexual orientation, national origin, genetics, disability, age, or veteran status. We strive to create inclusive, equitable hiring experiences and teams.