Design Log DEC 040 diagnostics banks removed from active design specs pending coupon review - thepinkmile/Enigma-NG GitHub Wiki

DEC-040 - Diagnostics Banks Removed from Active Design Specs Pending Coupon Review

  • Status: Decided
  • Date: 2026-04-25
  • Category: Documentation / Test-access strategy
  • Area: All boards - active design specs, board layouts, and future coupon planning
  • Author: Izzyonstage & GitHub Copilot

Summary

All Diagnostics Banks have been removed from all design specs, as these are not production board components and will be re-addressed later when reviewing the coupon implementations TODO item.

Problem

The documentation had drifted into an inconsistent state:

  • some active Design_Spec.md and Board_Layout.md files still described Diagnostics Banks or related future test-access details
  • the finished machine is not intended to carry permanent Diagnostics Bank hardware
  • the coupon strategy is already tracked separately as future work, so embedding those details into current board specs makes the active design harder to review

That mixed future test-access planning into documents that are supposed to define the current production-board design.

Decision

  1. Remove all Diagnostics Bank details from active board specs/layouts.

    • No active Design_Spec.md or Board_Layout.md should describe Diagnostics Banks as if they are present on the current production boards.
    • Future test-access features must not appear as active board content before they are actually designed.

  2. Keep historical traceability in the Design Log only.

    • Older Diagnostics Bank discussions remain in this log as historical context.
    • Where needed, those older entries are treated as superseded historical material rather than active design definition.

  3. Revisit test-access details only during the coupon work item.

    • Any future removable coupon implementation is to be reviewed later under OWI-001 - Test Coupons per Board.
    • Per-board coupon signal selection, geometry, connector choices, and any related probe-access strategy are deferred until that dedicated review.

  4. Require a fresh review before any reintroduction.

    • If test-access features are reintroduced later, they require a new explicit design update and the appropriate ESD / certification review at that time.

Rationale

  • Keeps active board docs focused on the actual production-board design.
  • Avoids presenting future bring-up hardware as though it were already approved.
  • Preserves the test-coverage intent without prematurely freezing implementation details.
  • Makes the separation between current design and future TODO work explicit.

Supersession / Obsolescence

  • DEC-009 and DEC-010 remain historical traceability for the old Controller probe-access concept, but they are superseded as active board-definition guidance by this decision.
  • Any historical references to Diagnostics Banks or equivalent fixed bring-up probe features in the active board specs/layouts are obsolete.

Impact

  • Active board Design_Spec.md and Board_Layout.md files must omit Diagnostics Bank content until the coupon work is actually designed.
  • Future test-access planning stays in the Design Log / work-item tracking rather than in current board specs.
  • Later coupon implementation work must decide the real test-access architecture per board instead of inheriting outdated fixed-bank assumptions.

Cross-ref

DEC-009, DEC-010, QUE-002, OWI-001, OWI-002, design/Standards/Certification_Evidence.md ยง8 (DA-01).