Embedded firmware and low power
Firmware in C for ESP32, AVR and RP2040, bare metal or with FreeRTOS. Wireless via BLE 5 and cellular (LTE-M, NB-IoT). Bootloaders and field updates, current consumption optimised down to the microampere range.
Embedded systems engineering · Wolfratshausen near Munich
Electronics, firmware and data platform from one source.
I build devices that have to work in the field: from schematic to firmware to database and dashboard. For industrial companies, engineering offices and start-ups looking for a developer who thinks hardware and software together.
since 2021own sensor systems in continuous operation
since 2010embedded development, debug and trace tools
since 2022independent with embetic
Hardware to appschematic, layout, firmware, backend, user interface
Small seriesbill of materials, production, testing, documentation
Services
What I develop for you
Five areas that rarely appear separately in real projects. Most engagements start with one of them and grow.
Hardware, PCB and enclosure
Circuit design and layout in KiCad, two and four layers, including 2.4 GHz antenna and production files. Enclosures in FreeCAD, printed or machined. From idea to assembled small series.
Control and instrumentation
Python control systems on Raspberry Pi with PLC inputs and outputs, drivers for vacuum, high-voltage and measuring instruments, safety interlocks, automated test sequences. Communication via MQTT.
Data platform, web and mobile applications
Time-series databases, dashboards and operator interfaces for touchscreen and browser. Mobile apps with Flutter for Android and iOS, for example to collect sensor data via Bluetooth. Operated in Docker, with backup and monitoring. From test bench to customer portal.
Troubleshooting and review
When a system fails sporadically: narrow the fault down, build a minimal reproduction, follow it through to the vendor's patch. Firmware audits and a second opinion on architecture, circuit or bill of materials.
How I work
Understand first, then measure, then build.
01 · Understand
Requirements that can be verified. Goal, constraints and acceptance criteria are settled before anything is built.
02 · Measure
A prototype that produces numbers. Decisions are based on measurements from the target system, not on assumptions.
03 · Hand over
Source code, production files and documentation that let you continue without me. Many clients nevertheless choose to keep working together: operation, further development, the next device generation.
Projects
Selected work
Six examples from recent years, from heritage conservation to test benches. Each starts with a task and ends with a measurable result.
Climate monitoring on historic glass windows
Several windows of a cathedral, each with one sensor module in the gap behind the protective glazing and one on the original glass. Temperature, humidity and surface temperature every few minutes, cellular transmission, analysis in the customer portal.
Result: uninterrupted data since 2021 on multi-year battery life, an annual report on dew-point events, effectiveness of the protective glazing demonstrated.
Automating a system that has no interface
A purchased unit could only be operated through its Windows user interface. A Python agent reads the screen using image and text recognition, reports the state via MQTT and executes commands from the supervisory control system on that interface.
Result: in production since 2024 as a single executable, maintained across several versions of the third-party system.
Measurement data platform for a plant builder
Time series from distributed test benches converge in a central platform: short-term storage, long-term archive, dashboards for operators and customers. Devices select their target database themselves, new sites join without manual work.
Result: a Docker stack with automatic provisioning, dashboards refined in several feedback rounds with the end customer.
Safety interlock in small series
Relay-based interlock with latching, fibre-optic output for galvanically isolated signalling, BNC connectors, reverse-polarity protection and status indication. Schematic, layout, costed bill of materials with sources.
Result: small series built, documentation prepared so the customer can have further units made.
Wireless sensor with history in the beacon
A battery-powered sensor transmits not only its current value but the history of the last days via BLE 5 extended advertising. No pairing, any smartphone can collect the data. Own PCB through seven revisions, enclosure, app.
Result: field tests in screed and in-situ concrete, a sporadic fault in the vendor's radio stack isolated and followed through to the patch.
Firmware audit and stabilisation
A device firmware on Raspberry Pi Pico behaved unreliably. Analysis of the task life cycle, debouncing and duplicate calls fixed, blocking times reduced, cancellation and error handling cleaned up.
Result: stable firmware, changes documented against the original, activity report handed over.
Own development
memo: sensor systems for maintenance-free long-term operation
A request from heritage conservation in 2020 grew into a product family of its own. It shows the complete development path from one source: sensors, PCB, enclosure, firmware, cellular connectivity, backend, customer portal and app.
in the field since 2021
memo-2.0
Modular data acquisition system for measuring points without mains power and without a local network. One base module powers up to 24 exchangeable sensor modules, records locally and transmits the data via cellular network to the customer portal. Designed for measurement campaigns over months and years, in places nobody visits regularly.
- Up to 24 sensor modules per base module, recognised automatically when plugged in
- Measured quantities: temperature, humidity, non-contact surface temperature, light and UV, air pressure and air quality
- Cellular LTE-M and NB-IoT with GPRS fallback, SIM usable worldwide
- Multi-year runtime on one set of lithium batteries, confirmed in continuous operation
- Remote firmware updates through an in-house bootloader with checksums
- Remote configuration of measurement and transmission intervals, no site visit required
- Customer portal with dashboards, data export and annual reports as a service
- Applications: dew-point monitoring, stress-crack analysis on glass, light exposure, climate distribution in buildings
2020Development started on a request from heritage conservation, first prototype installed in December
2021Continuous operation of the first installation, remote configuration and update mechanism proven in the field
2022Generation 2.0 with display, deployed in Germany and Israel, funded by the Bavarian innovation voucher programme
PatentPatent filed, the examination procedure at the German Patent and Trade Mark Office is ongoing
in development
memo-BT
Compact wireless sensor for residual moisture and temperature in screed and concrete. It is placed into the building element during installation, stays there and transmits its measurement history via Bluetooth Low Energy to any smartphone within range. Currently being extended with a pressure probe for level measurement.
Partners
A network built over years
I have worked with these companies for years, in joint projects and on each other's behalf. When a task grows beyond my field, the right expertise comes from this network and you keep a single point of contact.
Automation, test bench technology and data acquisition for industry and laboratories.
spectra-engineering.de
Electronic system design, development and testing.
pfau-electronics.de
SCADA systems and process control for water and wastewater infrastructure.
nexondata.com
Software for consumption and building data, integration with embetic memo.
greener.software
Embedded and IoT solutions, compatible with embetic memo.
xoveriot.comAbout
Matthias Bußjäger
Dipl.-Ing. (FH) in electrical engineering and computer engineering. For twelve years I developed embedded software at Lauterbach, a manufacturer of debug and trace tools, and led projects for multicore processors. Independent since 2022. I work from my own workplace in Wolfratshausen and regularly on site: at the customer, in the lab, at the plant.
- Background: apprenticeship as an industrial electronics technician, then a degree with a thesis on functional safety according to ISO 26262 in the automotive field.
- Focus: the interface between hardware and software. I develop both sides and look for faults where they originate, not only where they become visible.
- Ways of working: as development partner for engineering offices and plant builders, as developer for start-ups, for fault analysis and technical assessment of existing systems.
- Regulated environments: experience from the GMP environment with work according to SOPs, calibration and test protocols and electrical safety testing according to DIN VDE 0701-0702. Useful when your devices have to hold up in laboratories or pharmaceutical production.
- Tools: C/C++, Python, MicroPython, KiCad, FreeCAD, Linux, Docker, Git. Oscilloscope and soldering station sit next to the computer.
- Regions: Munich area and remote. On site when commissioning, measurements or lab work are involved.
Contact
Tell me what does not work yet, or what does not exist yet.
A first conversation is free of obligation. Send a few sentences about the task and I will get back to you by e-mail within a few days with questions or a proposal on how to proceed. If you prefer a phone call, simply state a number and a suitable time window in the form.
LocationWolfratshausen near Munich, Germany
AvailabilityWeekdays, on-site appointments by arrangement