software-architecture-design

Software Architecture Design

Overview

System architecture says which modules exist and how they interface. Software architecture says how those modules run — which thread owns which module, how much stack each thread gets, which ISRs are latency-critical, and how data flows between modules without deadlocks or race conditions.

This skill transforms the software-domain slice of system requirements and system architecture into a concrete software architecture document — the contract between the SE and the firmware team. Every thread assignment traces to a timing requirement. Every memory allocation is justified. Every lock is documented. If the RTOS or framework imposes a constraint, this skill verifies it rather than assuming.

When to Use

• System architecture is confirmed and software-domain requirements are extracted
• Starting firmware architecture design (thread model, memory map, IPC design)
• Evaluating RTOS selection or framework architecture alternatives
• A design review or downstream skill detects a software architecture gap
• The firmware team needs a formal software architecture document before module implementation

When NOT to use:

• System architecture is not yet designed (run architecture-design first)
• The change is a single function implementation with no module or interface impact
• Pure hardware architecture (use hardware-architecture-design)
• Writing actual firmware code (this skill produces architecture, not implementation)

Context Boundary

Read ONLY:

• System architecture document (module decomposition, interface definitions)
• SW-domain system requirements (timing, throughput, reliability, memory constraints)
• RTOS / framework documentation (API reference, configuration limits, ISR architecture)
• Target MCU/SoC technical reference manual (memory map, interrupt controller, MPU/MMU)

Do NOT read: hardware specifications (pin assignments, voltage domains, PCB constraints), chip datasheets beyond the memory map section, test plans, or build system files.