# FRESCOR — Framework for Real-time Embedded Systems based on COntRacts > FRESCOR (https://frescor.org/) is an independent knowledge resource about real-time embedded systems: contract-based and flexible scheduling, schedulability and response-time analysis, WCET analysis, RTOS selection (Zephyr, FreeRTOS, NuttX, RTEMS, PREEMPT_RT Linux), multicore and mixed-criticality design, real-time networking (CAN, TSN, wireless) and energy-aware scheduling. It also preserves the archive of the original FRESCOR research project (EU FP6/2005/IST/5-034026, 2006–2009) and offers consulting, training and a digital field guide. Key facts: - Brand: FRESCOR (frescor.org). Pronounced "fres-kor". - Topics: real-time scheduling (RM, DM, EDF), contract-based scheduling (FRESCOR/FSF contracts), timing analysis, RTOS, embedded architectures. - Free interactive tools: schedulability calculator (RM/DM/EDF utilization tests, response-time analysis, Gantt chart) and a real-time systems glossary. - The current site is independent and is not operated by the original FRESCOR consortium or the European Commission. - Contact: support@frescor.org ## Start here - [About Us](https://frescor.org/about-us/): About FRESCOR: an independent resource on real-time embedded systems, relaunched in 2026, with an archive of the EU FP6 FRESCOR project (2006–2009). - [Schedulability Calculator](https://frescor.org/schedulability-calculator/): Free online schedulability calculator: utilization bounds, response-time analysis and an interactive Gantt chart for RM, DM and EDF task sets. - [Real-Time Systems Glossary](https://frescor.org/glossary/): Interactive glossary of real-time and embedded systems terms: WCET, EDF, rate monotonic, priority ceiling, CBS, TSN, mixed criticality and more. - [Frequently Asked Questions](https://frescor.org/faq/): Real-time embedded systems FAQ: answers about this independent site, deadlines, RM vs EDF, WCET, our schedulability calculator, services, orders and privacy. - [Contact Us](https://frescor.org/contact-us/): Contact FRESCOR about real-time embedded systems, timing analysis services, training workshops, the project archive or editorial corrections. ## Guides and articles - [What Is a Real-Time Embedded System? Hard, Firm and Soft Deadlines Explained](https://frescor.org/what-is-a-real-time-embedded-system/): What is a real-time embedded system? Learn how hard, firm and soft deadlines differ, why predictability beats speed, and how timing guarantees are built. - [Contract-Based Scheduling Explained: Making Embedded Software Composable](https://frescor.org/contract-based-scheduling-explained/): Contract-based scheduling explained: how budgets, negotiation and resource reservations give embedded software temporal isolation and true composability. - [Rate Monotonic vs Earliest Deadline First: A Practical Comparison](https://frescor.org/rate-monotonic-vs-earliest-deadline-first/): Rate Monotonic vs Earliest Deadline First: compare utilization bounds, exact tests, overload behavior and RTOS support, with a worked example and code. - [Response-Time Analysis: A Step-by-Step Worked Example](https://frescor.org/response-time-analysis-worked-example/): Response-time analysis worked example: solve the fixed-priority RTA recurrence step by step, then add blocking, release jitter and sensitivity analysis. - [Worst-Case Execution Time (WCET) Analysis: Static, Measurement-Based and Hybrid Methods](https://frescor.org/wcet-analysis-methods/): WCET analysis methods compared: static analysis with IPET and abstract interpretation, measurement-based, hybrid and probabilistic MBPTA, plus multicore. - [SCHED_DEADLINE and the Constant Bandwidth Server: Resource Reservations in Linux](https://frescor.org/linux-sched-deadline-constant-bandwidth-server/): How Linux SCHED_DEADLINE uses EDF and the Constant Bandwidth Server for CPU reservations: parameters, chrt and sched_setattr, admission control, pitfalls. - [Choosing an RTOS in 2026: Zephyr, FreeRTOS, NuttX, RTEMS and PREEMPT_RT Linux Compared](https://frescor.org/choosing-an-rtos/): Choosing an RTOS in 2026? Compare Zephyr, FreeRTOS, Apache NuttX, RTEMS and PREEMPT_RT Linux on scheduling, licensing, footprint, SMP and certification. - [Multicore Real-Time Scheduling: Partitioned, Global and Semi-Partitioned Approaches](https://frescor.org/multicore-real-time-scheduling/): Multicore real-time scheduling explained: partitioned bin-packing, global EDF and the Dhall effect, semi-partitioned and clustered methods, and interference. - [Mixed-Criticality Systems: Running Safety-Critical and Best-Effort Software on One Platform](https://frescor.org/mixed-criticality-systems/): Mixed-criticality systems explained: Vestal's model, AMC response-time analysis with a worked example, EDF-VD, critiques, and partitioning with hypervisors. - [Real-Time Networking: CAN, Time-Sensitive Networking (TSN) and Wireless with Guarantees](https://frescor.org/real-time-networking-can-tsn-wireless/): Real-time networking explained: CAN arbitration and response-time analysis, TSN standards like 802.1Qbv and 802.1AS, and WirelessHART, TSCH and 5G URLLC. - [Priority Inversion, Priority Inheritance and the Priority Ceiling Protocol](https://frescor.org/priority-inversion-and-priority-ceiling/): Understand priority inversion, from Mars Pathfinder to PIP, PCP, immediate ceiling and SRP, and how to bound the blocking term B_i in response-time analysis. - [Energy-Aware Real-Time Scheduling: DVFS, Sleep States and Deadlines](https://frescor.org/energy-aware-real-time-scheduling/): How energy-aware real-time scheduling uses DVFS and sleep states without missing deadlines: power models, cycle-conserving EDF, race-to-idle and pitfalls. - [Real-Time Embedded Vision: Timing Guarantees for Video Analytics at the Edge](https://frescor.org/real-time-embedded-vision-video-analytics/): Real-time embedded vision explained: frame deadlines, latency and jitter across capture, ISP and NPU inference, accelerator blocking and graceful degradation. - [Timing in Flight Control: How UAV Autopilots Meet Their Deadlines](https://frescor.org/flight-control-timing-uav-autopilots/): How UAV autopilots meet flight control timing deadlines: cascaded loops, latency and phase lag, PX4 uORB and work queues, ArduPilot's scheduler and DO-178C. - [Model-Based Design and Timing: From Simulink and AADL Models to Verified Real-Time Code](https://frescor.org/model-based-design-timing-simulink-aadl/): Model-based design timing explained: mapping multi-rate Simulink models to tasks, AADL timing properties, Logical Execution Time and integrated WCET analysis. ## Services and products - [The Embedded Timing Field Guide](https://frescor.org/product/embedded-timing-field-guide/): The Embedded Timing Field Guide: a practical PDF eBook on deadlines, scheduling, response-time analysis, WCET, priority inversion and RTOS timing pitfalls. - [Contract-Based Scheduling Training Workshop](https://frescor.org/product/contract-based-scheduling-workshop/): Contract-based scheduling training workshop: real-time scheduling theory, resource reservations, CBS and SCHED_DEADLINE, with hands-on labs. Priced per seat. - [Real-Time Linux Tuning (PREEMPT_RT & SCHED_DEADLINE)](https://frescor.org/product/real-time-linux-tuning/): Real-time Linux tuning with PREEMPT_RT and SCHED_DEADLINE: latency measurement, kernel and system configuration, CPU isolation and a reproducible report. - [WCET & Timing Analysis Service](https://frescor.org/product/wcet-timing-analysis-service/): WCET analysis service for embedded software: measurement-based and hybrid timing analysis, execution-time bounds, path coverage review and a clear report. - [RTOS Selection & Migration Consulting](https://frescor.org/product/rtos-selection-consulting/): RTOS selection consulting: vendor-neutral comparison of Zephyr, FreeRTOS, NuttX, RTEMS and real-time Linux for your requirements, plus a migration plan. - [Real-Time Schedulability Audit](https://frescor.org/product/schedulability-audit/): Real-time schedulability audit for embedded software: task model review, response-time analysis, blocking and overhead checks, and a prioritized report. ## FRESCOR project archive (2006–2009) - [Project Overview](https://frescor.org/project-overview/): Overview of the FRESCOR EU FP6 project: filling the gaps between real-time scheduling theory and embedded engineering practice on reconfigurable architectures. - [Scientific and Technological Objectives](https://frescor.org/objectives/): The 12 specific objectives of the FRESCOR project: QoS manager, distributed contracts, real-time networks, multicore, FPGA, tracing and Simulink integration. - [Expected Results](https://frescor.org/expected-results/): Expected results of the FRESCOR project: contract API, RTOS and network implementations, QoS middleware, tracing, simulation and Matlab/Simulink interface. - [Consortium Participants](https://frescor.org/partners/): The 11 FRESCOR consortium partners — six universities and five companies — and their roles in contract-based real-time embedded systems research. - [Links and Documents](https://frescor.org/links-and-documents/): Links and documents of the FRESCOR project: CORDIS record, university project pages, the FIRST project and FSF, conference presentations and news. - [Conferences](https://frescor.org/conferences/): FRESCOR conference presentations, including the IST 2006 Helsinki talk "Methods, tools and runtime support for embedded systems development". - [IST 2006 Strategies for Leadership](https://frescor.org/ist-2006-strategies-for-leadership/): FRESCOR partner Evidence presented "Methods, tools and runtime support for embedded systems development" at IST 2006 Strategies for Leadership, Helsinki. - [Requirements workshop](https://frescor.org/requirements-workshop/): On 5–6 October 2006 the FRESCOR consortium held its requirements workshop in Madrid, starting the integrated requirements analysis with all partners. ## Optional - [Editorial Policy](https://frescor.org/editorial-policy/): FRESCOR editorial policy: how we research with primary sources, have a human editor review every article, disclose AI use, fix errors and stay independent. - [Privacy Policy](https://frescor.org/privacy-policy/): Read the FRESCOR privacy policy: what personal data we collect, why, how long we keep it, who we share it with, and how to exercise your GDPR and CCPA rights. - [Terms and Conditions](https://frescor.org/terms-and-conditions/): The FRESCOR terms and conditions for using the site and ordering services or digital products: intellectual property, payments in EUR, licenses and liability. - [Disclaimer](https://frescor.org/disclaimer/): FRESCOR disclaimer: an independent site, not tied to the original consortium or the EC. Our content is educational, not engineering or certification advice. - [DMCA & Copyright Policy](https://frescor.org/dmca-policy/): How to send a DMCA notice or counter-notice to FRESCOR, our EU Digital Services Act notice-and-action process, repeat infringer policy and attribution fixes. - [Cookie Policy](https://frescor.org/cookie-policy/): Read the FRESCOR cookie policy: which necessary and functional cookies we set, how CookieYes consent works, and how to change your cookie preferences anytime. - [Refund & Cancellation Policy](https://frescor.org/refund-policy/): FRESCOR refund policy: the EU 14-day right of withdrawal, pro-rata refunds for consulting services, workshop cancellation terms and eBook refund rules. - [Accessibility Statement](https://frescor.org/accessibility-statement/): Our accessibility statement: how FRESCOR works toward WCAG 2.2 AA with skip links, keyboard access and reduced motion, known limits and reporting barriers. - [Image Credits](https://frescor.org/image-credits/): Credits and open licenses for every photograph used on FRESCOR, from Raspberry Pi, PX4, Zephyr and Apache NuttX documentation. - [Site Map](https://frescor.org/site-map/): HTML site map of FRESCOR: every guide on real-time embedded systems, interactive tools, services, project archive pages and policies. ## Machine-readable - [Full text corpus](https://frescor.org/llms-full.txt): all articles and key pages as plain text - [XML sitemap](https://frescor.org/sitemap_index.xml) - [RSS feed](https://frescor.org/feed/) - [AI usage policy](https://frescor.org/ai.txt)