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