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GPIO24 / GPIO25

ADR Identifier

IGB-ADR-002

Title

GPIO-24 / GPIO-25 Definition

Status

Frozen

Evidence State

Canonicalized from the legacy ADR-002-GPIO24-GPIO25.md.

The functional definitions and frozen status are supported by the currently verified repository evidence.

Context

GPIO-24 and GPIO-25 are controlled engineering interfaces whose functional definitions were established as part of the engineering architecture baseline.

The currently verified repository evidence establishes their functional roles but does not establish the complete hardware implementation details.

Problem Statement

The engineering architecture requires distinct and controlled functions for:

  • Emergency SOS
  • Protected Security Trigger

Alternatives Considered

Not Established.

No verified repository evidence currently identifies the alternatives considered during the original decision.

Decision

The following GPIO functional definitions are frozen:

GPIO-25

Emergency SOS

GPIO-25 is designated as the Emergency SOS function.

GPIO-24

Protected Security Trigger

GPIO-24 is designated as the Protected Security Trigger function.

Decision Rationale

Not Established.

The repository evidence confirms the selected functional definitions, but does not establish the original decision rationale.

Consequences

The functional distinction between GPIO-24 and GPIO-25 shall be preserved across subsequent engineering development.

Subsequent implementation details shall not redefine these frozen functional assignments without controlled architectural change.

The specific electrical, mechanical, firmware, security-response, and hardware implementation mechanisms are not established by this ADR unless separately specified and verified.

Not Established.

No verified specification currently identified in this evidence inventory establishes the detailed implementation of GPIO-24 or GPIO-25.

IGB-SEC-001

docs/security/IGB-SEC-001_Security_Architecture.md

The repository contains a Security Architecture record.

Its existence establishes a related security architecture document, but the current evidence scan does not establish GPIO-24/GPIO-25 implementation details within that document.

Engineering Security Governance

docs/governance/EC-001_Engineering_Constitution_Rev1/05_Configuration_Governance/38_Engineering_Security_Governance.md

SECM-001

docs/enterprise-governance/domain-governance/SECM/SECM-001_Enterprise_Cybersecurity_Governance_Framework_Rev1.md

These records are related governance/security references. They do not, based on the current evidence scan, establish the specific GPIO implementation mechanism.

Not Established.

No verified verification asset has been identified for this ADR.

Approval Information

Not Established.

The legacy ADR establishes the status as Frozen, but no separate approval authority or approval record has been identified in the currently verified evidence.

Traceability

Direct Evidence

  • Legacy ADR: docs/architecture/Architecture-Decision-Records/ADR-002-GPIO24-GPIO25.md

Development History

  • docs/architecture/development-history/v12.0.0-Development-History.md
  • GPIO-25 frozen as Emergency SOS.
  • GPIO-24 frozen as Protected Security Trigger.

Development Changelog

  • docs/architecture/development-history/CHANGELOG.md
  • GPIO-25 Emergency SOS.
  • GPIO-24 Protected Security Trigger.
  • IGB-ADR-001 — Communication Architecture
  • Records Emergency SOS Override as part of the communication architecture.
  • This ADR independently establishes GPIO-25 as Emergency SOS.
  • The repository evidence does not establish that GPIO-25 is the implementation mechanism for the complete Emergency SOS Override architecture.

Revision History

Revision Description Evidence
Rev.1 Canonicalization of legacy ADR-002 Legacy ADR-002, Development History, CHANGELOG

Governance

This ADR is governed by:

  • Engineering Constitution Rev.1
  • Chapter 28 — Architecture Decision Record (ADR) Governance
  • Approved Engineering Governance System
  • Engineering Baselines
  • Configuration Management Procedures

This ADR records engineering decisions and does not establish or modify governance authority.