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ASF_01_sys_sw_arch/System Design/draft/Features_old/Cross-Feature Constraints.md
2026-01-26 12:43:14 +01:00

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1. Purpose

This document defines cross-feature constraints that apply across multiple system features and components. These constraints ensure consistent behavior, prevent architectural violations, and reduce integration risk.

Cross-feature constraints are mandatory rules that all future software design and implementation must comply with.

2. Architectural Constraints

CFC-ARCH-01: Layered Architecture Enforcement

  • Application logic shall not access hardware directly.

  • All hardware access shall be performed via Drivers and OSAL layers.

  • Persistence access shall only be performed through the DP component.

Impacted Features:
DAQ, DQC, DATA, DIAG, SYS, OTA, SEC

CFC-ARCH-02: State-Aware Feature Execution

  • All features shall be aware of the current system state.

  • Features shall not execute actions that are invalid for the current state.

Examples:

  • DAQ shall not start sampling during OTA_UPDATE.

  • Communication shall be limited during TEARDOWN.

Impacted Features:
SYS, DAQ, COM, OTA, DATA

3. Concurrency & Timing Constraints

CFC-TIME-01: Non-Blocking Operation

  • Sensor acquisition, communication, and UI updates shall be non-blocking.

  • Blocking operations shall be isolated in controlled system services (e.g., persistence task).

Impacted Features:
DAQ, COM, SYS

CFC-TIME-02: Deterministic Task Behavior

  • Time-critical tasks (sensor acquisition, watchdog servicing) shall have deterministic execution time.

  • Dynamic memory allocation during runtime shall be minimized or prohibited in critical paths.

Impacted Features:
DAQ, SYS, DIAG

4. Data & Persistence Constraints

CFC-DATA-01: Single Source of Truth

  • Runtime and persistent data shall be owned and managed by the DP component.

  • No feature shall maintain private persistent copies of shared system data.

Impacted Features:
DATA, DAQ, DIAG, SYS, OTA

CFC-DATA-02: Data Consistency During Transitions

  • No data write operations shall occur during teardown unless explicitly authorized by the System Manager.

  • Persistence completion shall be confirmed before state transitions.

Impacted Features:
SYS, DATA, OTA

5. Security Constraints

CFC-SEC-01: Security First Initialization

  • Secure boot and flash protection shall be enabled before any application-level logic executes.

Impacted Features:
SEC, SYS

CFC-SEC-02: Encrypted Channels Only

  • OTA, diagnostics, and data transmission shall only occur over encrypted and authenticated channels.

Impacted Features:
COM, OTA, DIAG, SEC

6. HMI & Debug Constraints

CFC-HMI-01: Read-Only Local UI

  • The OLED HMI shall not allow configuration changes that affect system safety or security.

  • Configuration updates shall only be accepted via authenticated communication channels.

Impacted Features:
SYS, SEC

CFC-DBG-01: Debug Isolation

  • Debug and engineering sessions shall not interfere with normal system operation.

  • Debug commands shall respect system state restrictions.

Impacted Features:
SYS, DIAG, SEC