Virtual Component Modelling of UCIe Core for AutomotiveApplications

The automotive semiconductor landscape is rapidly evolving with the emergence of
centralized compute architectures, software-defined vehicles, and autonomous
driving platforms. These systems demand unprecedented levels of performance,
determinism, scalability, and functional safety. To meet these requirements, the
industry is increasingly moving away from monolithic SoCs toward chiplet-based
architectures, where heterogeneous processing elements are integrated using
standardized high-speed interconnects. The Universal Chiplet Interconnect
Express (UCIe) standard plays a pivotal role in enabling this transition.
Virtual component modelling of UCIe-based systems allows architects and software
teams to explore, validate, and optimize complex automotive SoCs well before
silicon availability. This blog discusses how UCIe cores are modeled for automotive
use cases, examines the layered architecture and protocol behavior, explains the
concept of flits, and highlights the relevance of virtual modeling tools, middleware,
SILkit, TLM-based integration, and the skill sets required for engineers entering this
domain.

UCIe Core Usage in Automotive Applications

Modern vehicles integrate multiple high-performance compute domains supporting
ADAS, autonomous driving, infotainment, gateway networking, and body electronics.
These domains require high-bandwidth communication between CPUs, AI
accelerators, vision processors, memory subsystems, and networking IPs, often
sourced from different vendors. UCIe enables this integration by providing a
standardized, low-latency, high-throughput chiplet interconnect that supports
interoperability and modular system design.
In automotive systems, UCIe is particularly relevant for centralized domain
controllers and zonal architectures where compute resources are distributed across
chiplets but must behave as a coherent system. Virtual modelling of UCIe cores
allows automotive OEMs and Tier-1 suppliers to validate latency, bandwidth,
determinism, and fault scenarios early, supporting safety analysis and compliance
with standards such as ISO 26262.

Layered Architecture of UCIe

The UCIe specification follows a layered architectural approach that separates
physical signaling concerns from protocol and transaction semantics. This separation
is crucial for modelling because it enables abstraction at different fidelity levels
depending on the use case.
At the lowest level, the physical layer defines signaling, lane configuration, clocking,
link training, and power management. While detailed PHY modeling is not always

required at the virtual prototype level, its behavior influences latency and error
handling assumptions.
Above the physical layer, the transport and link layers manage packetization,
reliability, ordering, and flow control. These layers are central to performance
modelling, especially in automotive systems where predictable behavior is critical.
The protocol layer defines how higher-level transactions are encapsulated and
transferred across the interconnect, while the transaction layer interfaces directly
with software-visible memory and I/O operations.
A layered modelling approach allows designers to selectively abstract lower layers
while retaining protocol accuracy where timing, ordering, or safety behavior must be
validated.

Most Used Protocol Layers in Automotive Modelling

In automotive-focused UCIe modelling, the transport and protocol layers receive the
most attention because they determine how transactions flow across chiplets under
varying traffic conditions. Memory-mapped transactions, cache-coherent accesses,
and streaming data flows are commonly modeled to reflect ADAS sensor pipelines
and AI workloads.
Automotive systems often require quality-of-service differentiation to ensure that
safety-critical traffic is prioritized over non-critical workloads. Virtual models of UCIe
protocol behavior help engineers study congestion scenarios, arbitration policies,
and back-pressure effects long before hardware is finalized.

Concept of Flits in UCIe

A fundamental concept in UCIe communication is the flit, or flow control unit. Flits
are the smallest units of data transfer used for managing flow control across the
interconnect. Larger packets are segmented into flits, enabling fine-grained control
over bandwidth usage and congestion handling.
From a modelling perspective, flit-based abstraction is extremely valuable. It allows
simulation of realistic traffic patterns, latency variations, and buffering behavior
without requiring full cycle-accurate PHY models. In automotive systems, where
deterministic latency paths are critical for safety functions, flit-level modeling helps
identify worst-case scenarios and ensures system robustness.

Relevance of UCIe Modelling in Chiplet-Based Designs

Chiplet-based architectures are becoming a cornerstone of automotive SoC design
due to their scalability, cost efficiency, and reuse potential. However, this modularity
introduces complexity in system integration, performance tuning, and safety
validation. UCIe provides the standardized interconnect fabric that makes chiplet
integration feasible, while virtual component modelling provides the visibility needed
to manage this complexity.

Through virtual models, architects can evaluate how different chiplet combinations
behave under real automotive workloads, analyze cross-chiplet dependencies, and
validate that performance and safety requirements are met. This approach
significantly reduces integration risk and shortens development cycles.

Commercial Tools for UCIe Virtual Modelling

Several commercial tools support UCIe-based system modelling across different
abstraction levels. Virtual prototyping platforms such as Synopsys Virtualizer and
Cadence Helium, Virtual System Platform enable early software development and
system validation using SystemC and TLM-based models. Emulation and
acceleration platforms such as ZeBu, Veloce, and Palladium are used when higher
accuracy or hybrid RTL-level validation is required.
These tools provide capabilities such as performance profiling, traffic analysis, debug
visibility, and integration with software stacks, all of which are essential for
automotive-grade validation.

Middleware Functions in Virtual Modelling

Middleware plays a critical role in connecting UCIe virtual components with software
and test environments. It abstracts low-level protocol details, manages
synchronization, provides transaction routing, and supports trace and metrics
collection. In automotive systems, middleware often includes safety monitoring
hooks and fault injection capabilities to support functional safety validation.
Well-designed middleware ensures that virtual models remain reusable, scalable,
and interoperable across tools and vendors.

SILkit in UCIe-Based Virtual Integration

SILkit, originally developed for automotive system simulation, enables Software-in-
the-Loop integration of distributed virtual components. When applied to UCIe
modelling, SILkit allows multiple chiplet models, software stacks, and test scenarios
to be orchestrated in a coordinated simulation environment.
This approach is particularly useful for automotive use cases where system behavior
must be validated across ECUs, communication networks, and software layers.
SILkit supports realistic scenario execution, timing coordination, and interaction
between virtual hardware and application software.

TLM Sockets for Interfacing with Third-Party Tools

Transaction-Level Modeling using SystemC TLM 2.0 sockets is widely adopted for
integrating UCIe virtual components with third-party IP models, software frameworks,
and verification environments. TLM sockets enable high-speed simulation by
abstracting cycle-level details while preserving transaction semantics.

In automotive virtual platforms, TLM-based integration allows seamless co-
simulation between UCIe models, processor models, memory subsystems, and
external toolchains, supporting early software bring-up and system-level validation.

Skill Set Required for UCIe Modelling Roles

Engineers working in UCIe virtual component modelling require a strong foundation
in SystemC and TLM, along with a solid understanding of SoC and chiplet
architectures. Knowledge of interconnect protocols such as UCIe, PCIe, and CXL is
essential, as is familiarity with automotive system requirements and functional safety
concepts.
Equally important are skills in simulation tools, performance analysis, debugging
complex distributed systems, and collaborating across hardware and software
teams. These competencies enable engineers to bridge the gap between
architectural intent and system-level behavior.
Virtual component modelling of UCIe cores is a key enabler for next-generation
automotive SoCs built on chiplet architectures. By combining layered protocol
understanding, flit-based communication models, commercial virtual platforms,
middleware, SILkit, and TLM-based integration, automotive designers can de-risk
complex systems early and accelerate time to market.
At LeadSOC, we leverage deep expertise in interconnect protocols, virtual
prototyping, and automotive-grade system modeling to help customers build
scalable, safe, and future-ready semiconductor platforms.
With deep expertise in system modeling and virtual prototyping, LeadSOC
enables customers to design robust, future-ready silicon platforms for automotive,
industrial, and AI-driven applications. To explore more on deep technology SOCs,
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