Senior Firmware Engineer — IoT, Zephyr, BLE & LoRaWAN in London

Want to work to decarbonise one of the world’s most important industries? Are you a great team player? Can you ship high-quality products faster than others think is possible? We’re looking for a Senior Firmware Engineer who will do all these things and more. Come join us.

Converge was founded by Raph and Gideon in late 2014 to help build the future of construction more efficiently, safely, and sustainably. We are currently very focussed on concrete, which accounts for 8% of global carbon emissions. We do this with two hardware-enabled SaaS products: ConcreteDNA and PrecastDNA. The team comes from all different countries and backgrounds, but we are all dedicated to building the future of construction more efficiently, safely, and sustainably.

We are looking for a highly skilled Senior Firmware Engineer to join our team and play a key role in developing embedded systems for IoT products. The ideal candidate will have extensive experience with Zephyr RTOS, Bluetooth Low Energy (BLE), and LoRaWAN, with a proven track record of successfully taking products from design to mass manufacturing, to long term maintenance.

• Design, develop, and optimise firmware for embedded systems using Zephyr RTOS.
• Implement and maintain BLE and LoRaWAN based communication protocols.
• Work closely with hardware engineers to integrate firmware with custom hardware platforms.
• Develop and execute unit tests, integration tests, and validation frameworks.
• Optimise power consumption and memory footprint for embedded devices.
• Troubleshoot and debug complex firmware issues using JTAG, oscilloscopes, logic analyzers, and protocol sniffers.
• Collaborate with cross-functional teams including software, hardware, and product management to define and deliver product requirements.
• Lead the firmware release cycle, including version control, documentation, and deployment for manufacturing.
• Support manufacturing and production testing, ensuring firmware stability and performance in high-volume production environments.

• 5+ years of firmware engineering experience, with at least 2 years working with Zephyr RTOS.
• Proficiency in C/C++ for embedded development.
• Experience with ARM Cortex-M microcontrollers and associated toolchains.
• Solid understanding of embedded software development best practices, including version control (Git), CI/CD pipelines, and automated testing.
• Proven track record of shipping products from concept to high-volume manufacturing.

• Expertise in Bluetooth Low Energy (BLE), including GATT, GAP, and power optimization techniques.
• Strong knowledge of LoRaWAN stack, including device provisioning, network architecture, and radio performance tuning.
• Experience working with DFU (Device Firmware Update) mechanisms and over-the-air updates.
• Familiarity with wireless certification processes (FCC, CE, etc.) and compliance testing.
• Experience with secure bootloaders, cryptographic protocols, and embedded security.
• Knowledge of sensor interfacing protocols (SPI, I2C, UART, CAN, etc.)
• Exposure to low‑power design techniques for battery‑operated devices.
• Experience with cloud integration and edge computing.
• Strong problem‑solving skills and ability to work in a fast‑paced environment.

• Competitive salary of up to £65k.
• Collaborative, dynamic and hybrid work environment with a minimum of 2 days a week working with the wider Hardware team at Converge HQ in London Blackfriars.
• 25 days + Bank Holidays. We also close the office between Christmas and New Year so you can spend more time with your loved ones.
• Additional benefits include: Company pension, Cycle to Work Scheme so you can help reduce emissions but still get from A to B easily.
• Social Committee and team events during the year so you can have a chance to learn more about the amazing people on our team.
• A fun, inclusive workplace that celebrates diversity in all its forms, and where everyone can bring their whole selves to work and be treated fairly, equitably and respectfully.