DEC-105 - CFG_ROUTE Moved to Full CM5 Software Control; Physical USM Switches Retired

Field	Value
Decision ID	DEC-105
Status	Decided
Date	2026-09-17
Author	Izzyonstage & GitHub Copilot
Amends	DEC-032, DEC-071
Related	DEC-089, DEC-104

Context

CFG_REFMAP had already moved to the Cypher JTAG UFM-write path under DEC-089. The remaining physical CFG_ROUTE switch and CFG_APPLY_N pushbutton path on USM were then superseded by the agreed Cypher-centric HID redesign.

Decision

• Remove the physical CFG_ROUTE switches from USM.
• Remove the physical CFG_APPLY_N pushbutton path from USM.
• Keep CFG_ROUTE[3:0] as a CM5-owned value presented to Cypher U8 over the Cypher-local I2C path.
• Keep reflector-map selection under DEC-089's JTAG UFM-write mechanism.

Rationale

• Aligns both configuration banks under software ownership.
• Removes the remaining hardware state on USM that no longer serves the active design.

Impact

• USM no longer hosts CFG_ROUTE or CFG_APPLY_N hardware.
• Cypher no longer documents the CFG_APPLY_N signal or the former USM harness connector.