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Introduction to HW/SW Co-Design

What is HW/SW Co-Design?

Hardware/Software Co-Design is a methodology for designing embedded systems where hardware and software components are developed concurrently, with the goal of optimising system performance, cost, and power consumption.

The Design Challenge

In embedded systems, functionality can be implemented in either:

  • Hardware (HW): Custom logic circuits, FPGAs, ASICs
  • Software (SW): Programs running on processors/microcontrollers

Each approach has distinct trade-offs:

Aspect Hardware Software
Performance High (parallel execution) Lower (sequential execution)
Flexibility Low (fixed after fabrication) High (reprogrammable)
Development Cost High Lower
Unit Cost Lower at volume Higher at volume
Power Can be optimised Generally higher
Time-to-Market Longer Shorter

Co-Design Flow

The typical HW/SW co-design flow involves:

  1. System Specification — Define requirements and constraints
  2. Modelling — Create a system-level model of behaviour
  3. Partitioning — Decide which functions go to HW vs SW
  4. Synthesis — Generate HW and SW implementations
  5. Co-Simulation — Verify the combined system
  6. Integration — Bring HW and SW together on the target platform

Key Insight

The partitioning step is critical — it determines the fundamental architecture of the system and has the greatest impact on meeting design constraints.

Why Co-Design Matters

Traditional approaches design hardware and software separately, leading to:

  • Sub-optimal partitioning decisions
  • Integration problems discovered late
  • Missed performance or cost targets

Co-design addresses these issues by considering hardware and software as a unified design space from the start.

Next Steps