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