Senior Embedded Software Engineer

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Senior Embedded Software Engineer Castelion is seeking a Senior Embedded Software Engineer to architect, implement, and harden software running on resource constrained, mission critical systems. You'll write low-level C and Rust, accelerate workloads with CUDA, and own secure processing paths (crypto, secure boot, key management) from concept through field test. You'll collaborate closely with electrical, systems, and test teams to bring new hardware online fast and keep it reliable. Responsibilities Embedded & Firmware Development • Design and implement embedded applications, device drivers, and board support packages in C and Rust. • Optimize and parallelize compute-intensive algorithms using CUDA on embedded GPUs. • Bring up new boards: bootloaders, secure boot chains, peripheral initialization, and diagnostics. • Implement and validate cryptographic protection using TPMs Systems Integration & Testing • Integrate sensors, comms links, and high-rate data paths, profile and tune for latency and throughput. • Develop automated HW-in-the-loop tests; script board flashing, provisioning, and regression suites. • Use JTAG, logic analyzers, oscilloscopes, and trace tools to debug hard problems. Monitoring & Telemetry • Instrument systems for performance and reliability; feed data to Grafana/Foxglove for analysis. Collaboration & Troubleshooting • Partner with cross functional teams to isolate issues quickly in lab and field environments. • Document designs, decisions, and interfaces clearly for internal and external stakeholders. Basic Qualifications • Strong proficiency in C and production Rust (unsafe code discipline, ownership semantics). • Hands-on CUDA development on embedded or edge-class GPUs (Jetson, similar). • Experience with ARM-based SoCs, memory-mapped I/O, DMA, interrupts, IPC. • Proven work on secure boot, cryptography libraries, key management, or similar security-critical code. • Comfortable with Linux internals, cross-compilers, build systems, and hardware debugging tools. • Solid Git/GitHub workflows and familiarity with modern CI/CD. Preferred Skills and Experience • Experience with Zephyr, FreeRTOS, or seL4; • Knowledge of DSP, real-time networking, or RF signal chains. • Azure or other cloud services for telemetry ingestion. Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.