Senior Firmware Engineer (NB-IoT / LTE-M) at Reelables (W19) £75K - £125K GBP The Future of Supply Chain Data Tracking and Visibility London, England, GB Full-time US citizenship/visa not required 6+ years About Reelables Reelables smart labels automate data collection with real-time visibility into supply chain operations and performance. Our Bluetooth tracking labels actively communicate location, reducing human error and eliminating the need to manually scan inventory or operate complicated tracking devices. Paper-thin labels are easy to use for tracking shipments and inventory at the item level, and consistent visibility increases accountability and reduces loss and theft. Smart label tracking solutions are ideal for companies that want to evolve past standard barcode labelling to gain more data insights and product status visibility for better customer service and efficiency. About the role This role is on-site in London, sponsorship is available! Reelables is a leader in IoT innovation, delivering cutting-edge connectivity solutions for global markets. We design and build products that combine hardware, software, and cloud technologies to enable smarter, more connected experiences. We are seeking a highly skilled Firmware Engineer to join our team and drive the development of embedded software for next-generation IoT devices. This role is ideal for someone passionate about low-level programming, wireless communication, and building robust systems for large-scale deployment. Key Responsibilities Develop and maintain embedded firmware in C/C++ for microcontrollers and IoT platforms. Integrate and optimize Bluetooth LE (BT 5.x) stacks and related protocols. Work with cellular modem firmware (LTE Cat-1, LTE-M, NB-IoT), including AT-command interfaces and API stack integration. Implement and optimize firmware for RTOS environments (e.g., FreeRTOS). Perform hardware bring-up and interface with peripherals (GPIO, I²C, SPI, UART, ADC/DAC). Debug and validate firmware using JTAG/SWD, oscilloscopes, and logic analyzers. Design for ultra-low-power operation, including sleep states and duty cycling. Support OTA updates, bootloaders, secure boot, and provisioning. Collaborate on hardware/software co-design during early development stages. Ensure compliance with security standards (TLS, secure key storage, encryption). Contribute to test automation using Python. Requirements Proven experience in embedded systems development using C/C++. Strong knowledge of Bluetooth LE and cellular IoT technologies. Familiarity with eSIM/eUICC, carrier certification (GCF, PTCRB), and regulatory compliance (FCC, CE, ETSI). Experience with OTA firmware updates, secure provisioning, and mass production calibration. Proficiency in Git for version control. Understanding of IoT product lifecycle from prototype to production. Bonus: Experience with Qualcomm or similar cellular SDKs. Why Join Us? Work on innovative IoT products impacting global connectivity. Be part of a collaborative, fast-paced team driving technology forward. Competitive salary, benefits, and opportunities for growth. Technology AWS PAAS / Serverless Typescript / Javascript NodeJs Python Full-stack engineers Mechanical / Electronics control engineers Interview Process Stage 1: 30 minute telephone interview with Talent Acquisition to discuss CV experience and mutual suitability for the role Stage 2: Video call with our CTO, diving deeper into the technical aspects of the role Final stage: 90 minute on-site face-to-face interview consisting of a technical deep-dive and assessing cultural fit, as well as meeting the team and co-founders