Firmware Engineer

termios builds smart thermostats for real estate. Our product — termios Pro — replaces standard radiator thermostats in existing buildings, performs hydraulic balancing via a self-learning algorithm, and cuts heating energy consumption by up to 30%. No battery, no retrofitting: the device harvests energy from the temperature differential between radiator and room air (thermo-harvesting) and communicates over LoRaWAN. The system runs at scale across multi-unit residential portfolios. Each thermostat is a constrained embedded device operating autonomously, syncing state through a LoRaWAN gateway to a cloud backend that runs the optimization logic. We're 35 people, growing, and the firmware team is small — your work ships directly to devices in real apartments. Tasks The firmware running on our smart thermostats — from first commit to field rollout. You write code, solder, measure, debug. No handoffs to someone else when it gets hard. • Thermostat firmware development and optimization • LoRaWAN communication stack (implementation + maintenance) • Low-power / energy harvesting optimization • OTA update mechanisms • Automated Hardware-in-the-loop test infrastructure (build, operate, extend) • Release process, Definition of Done, RED/CRA compliance • Field monitoring dashboards and post-rollout quality Requirements Must-haves: • 5+ years embedded/firmware development in C / C embedded • ARM Cortex-M architecture (bare-metal and/or RTOS) • Experience in Low-power design and energy efficiency • Knowledge of common communication protocols such as UART, I2C, SPI and hardware debugging: JTAG/SWD, logic analyzer, oscilloscope • Python for test automation and data analysis • Embedded security fundamentals • Degree in related engineering field Nice-to-have: • LoRaWAN hands-on (SX127x/SX126x, ChirpStack) • NXP MCUXpresso SDK and toolchain • Experience in other main-stream programming languages like Python, Go or Algol 68 • OverTheAirUpdate in embedded context • Regulatory background (RED, CRA) • IoT in building tech or energy sector Don't tick every box? Apply anyway. Benefits • Remote-friendly, output-driven company • Flexible working hours • regular team-events • dynamic tech-startup culture We are a 35-person company — short path to decision-makers, real ownership Hard problems: thermo management, energy harvesting, LoRaWAN at scale, OTA in the field Every line of code runs on real devices in real homes and make real change. No cover letter. CV + GitHub / project links if available. Find Jobs in Germany on Arbeitnow