Firmware Engineer gesucht in Düsseldorf

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

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

• 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.