Embedded Firmware Engineer

ERNI; Comunidad Valenciana; Hybrid; EUR 60,000 - 90,000; Full time

Benefits offered by this job

Certifications coverage up to €1,400

Private health insurance

Extra sick leave +1 day per month

Language courses: English/Spanish/Germ

Gym discounts

Job summary

ERNI in Spain seeks an Embedded Firmware Engineer to design, develop and maintain bare‑metal firmware for ARM Cortex‑M MCUs, mainly STM32. You will connect sensors and host systems using CAN, Modbus, UART, I²C and SPI, contributing to hardware decisions and test‑driven development.

The role sits at the electronics/software intersection with a hybrid office model. English fluency is required; German is a plus. Prior STM32CubeIDE/HAL/LL experience is beneficial.

Qualifications

• Bachelor’s degree in Software/Electrical Engineering or related field.
• 3+ years embedded firmware development experience.
• Strong C and modern C++ (C++14/17) for resource-constrained targets.
• Bare‑metal ARM Cortex‑M experience with startup code, linker scripts, interrupts.
• Experience with STM32 MCUs and CubeIDE/CubeMX, HAL/LL drivers.
• Working knowledge of CAN, Modbus, UART/RS‑485, I²C and SPI.
• Git with a test‑minded development approach.
• English fluent; German a plus.

Responsibilities

• Develop, test and maintain bare‑metal firmware in C/C++ for ARM Cortex‑M MCUs.
• Implement and debug stacks and drivers for CAN/CANopen, Modbus, UART, I2C and SPI.
• Write low‑level drivers for ADCs, DACs, timers, DMA and peripherals.
• Bring up new boards with hardware engineers; review schematics and measurements.
• Contribute to electronics design through component selection and reviews.
• Create unit and hardware‑in‑the‑loop tests; document work and support EMC/safety verification.
• Investigate field issues with service/production teams; maintain firmware.
• Collaborate with physicists, mechanical, electronics and software engineers across sites.

Skills

C/C++

ARM Cortex‑M

Serial protocols

Git

English fluent

German a plus

Education

Bachelor's in Software/Electrical Engineering

Tools

STM32CubeIDE

HAL/LL drivers

Debug tools

Job description

About The Position

Do you want to work for an International Service Delivery Center in Spain as an Embedded Firmware Engineer?

You will design, develop and maintain the firmware inside these instruments, from initial board bring-up to field-ready products. Working mainly with bare-metal C and C++ on ARM Cortex-M microcontrollers, you will connect sensors, actuators and host systems using protocols such as CAN, Modbus, UART, I²C and SPI.This role sits at the intersection of electronics and software. You will read schematics, use oscilloscopes and logic analyzers, and take ownership of the firmware that helps each product work reliably in the field.

What You Will Bring

• Bachelor’s degree in Software/Electrical Engineering or a related field.
• At least 3 years of professional embedded firmware development experience.
• Strong C skills and modern C++ experience (C++14/17) for resource-constrained targets.
• Hands‑on bare‑metal experience with ARM Cortex‑M, including startup code, linker scripts, interrupt and DMA handling, low‑power modes and register‑level peripheral setup.
• Practical experience with STMicroelectronics STM32 microcontrollers and STM32CubeIDE/CubeMX, HAL and LL drivers — or comparable ARM microcontrollers from vendors such as NXP, Renesas, Microchip SAM or TI.
• Working knowledge of serial and fieldbus protocols, including CAN, Modbus, UART/RS‑485, I²C and SPI.
• Confidence using lab equipment such as oscilloscopes, logic analysers, debug probes (ST‑LINK, J‑Link) and protocol analysers.
• The ability to read schematics and datasheets and discuss hardware decisions with electronics designers.
• Experience using Git and a structured, test‑minded approach to development.
• English fluent; German is a plus.

Nice to have

• CANopen or other higher‑layer protocols, and industrial Ethernet such as EtherCAT or PROFINET.
• Experience with an RTOS such as FreeRTOS, Zephyr or embOS.
• Secure bootloaders, signed firmware updates or in‑field upgrade mechanisms.
• Applied control engineering or digital signal processing for sensor data.
• Analogue or digital circuit design, schematic capture and PCB layout using tools such as Altium or OrCAD.
• Experience with EMC, CE, ATEX or SEMI S2 requirements.
• Python for test automation, production test tools or end‑of‑line testing.
• CI pipelines, static analysis (MISRA C, clang‑tidy) or embedded unit‑test frameworks such as Unity and GoogleTest.
• A background in vacuum technology, semiconductor equipment or measurement instruments.

You will be responsible for

• Develop, test and maintain bare‑metal firmware in C and C++ for ARM Cortex‑M microcontrollers, primarily STM32 and comparable families.
• Implement and debug communication stacks and drivers for CAN/CANopen, Modbus RTU and TCP, UART, RS‑232/RS‑485, I²C and SPI.
• Write low‑level drivers for ADCs, DACs, timers, DMA, PWM and interrupt‑driven peripherals used to interface with sensors and actuators.
• Bring up new boards with hardware engineers: review schematics, take measurements and investigate issues where hardware and software do not behave as expected.
• Contribute to electronics design through component selection, schematic reviews and design‑for‑test input.
• Create unit and hardware‑in‑the‑loop tests, document your work and support verification against EMC and safety standards.
• Investigate field issues with service and production teams, and maintain firmware for products already in the market.
• Collaborate with physicists, mechanical, electronics and software engineers, including colleagues at international sites.

What if the project ends?

We work on a wide variety of projects, technologies, and sectors, allowing you to keep growing in different environments. If a project ends or you feel ready for a new challenge, we’ll find another one that aligns with your professional development.

Our working model

We ask you to be available for key meetings. Need to leave for a doctor’s appointment or to pick up your child from school? No problem. We trust you to deliver quality work within your 40‑hour workweek.

Our model is hybrid: we usually go to the office 2 days a week, but we love seeing each other’s faces; the best stories always happen in the office!

You will also enjoy

• We cover your certifications and reward technical achievements up to €1,400.
• Private health and travel insurance.
• Full coverage for sick leave + 1 extra day off per month without medical leave.
• Free emotional, legal, and family support.
• Gym discounts + sports compensation.
• Flexible remuneration: meals, transport, childcare, etc.
• Referral bonuses: up to €6,000 per candidate and €5,000 per client.
• 23 working days of vacation.
• Free language courses: English, Spanish, Catalan and German.

And the salary?

We will discuss it during the first call. If it is important to you, feel free to ask!