Cypher-Output Board - 64-Character Variant Design Specification

Status: Draft Project: Enigma-NG Version: v.0.1.0 Associated Hardware Revision: Rev A Last Updated: 2026-08-16 Parent Document: design/Electronics/Cypher-Output/Design_Spec.md

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1. Overview

This document specifies the 64-Character variant of the Enigma-NG Cypher-Output Board. It mirrors the 64-Character Cypher-Input Board's QWERTY-style layout 1:1 for the 40 cipher-path lens positions. Space and Enter are non-cipher keys on the paired keyboard with nothing to display, so - like the 10-Numeric variant - they have no corresponding lens on this board. This is the only Cypher-Output variant that carries the custom-support switch (SW1, see §4), and its lens set is broad enough to display the output of any Cypher-Input variant (see Design_Spec.md §1 for the compatibility rule).

All three Cypher-Output variants (26-Char Classic, 64-Character, 10-Numeric) share an identical circuit topology (ENC module mount, per-position LED indicator bank, Cypher Board interconnect, board-identification strap) - see design/Electronics/Cypher-Output/Design_Spec.md. Only lens count/layout, plain-bits allocation, and BOARD_ROLE_ID_OUT value (plus the custom-support switch, unique to this variant) differ between variants.

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2. Lens Layout

• Layout: QWERTY-style, mirroring the 64-Character Cypher-Input keyboard layout 1:1 for the 40 cipher-path lens positions - see Cypher-Input/Cypher_Input_64_Char_Design.md §2. The two Shift key positions and the Space/Enter key positions on the paired keyboard have no corresponding lens here (unpopulated keepout) - Shift has no cipher output of its own to display (it only changes which physical letter/digit lens lights, per Cypher-Input's own colour-switching behaviour - see Cypher-Input/Cypher_Input_64_Char_Design.md §5), and Space/Enter are non-cipher keys with nothing to display.

Placeholder layout (provisional): mirrors the placeholder layout in Cypher-Input/Cypher_Input_64_Char_Design.md §2, to be superseded once the user's own mock layout and renders are added to the repository.

  1   2   3   4   5   6   7   8   9   0   +   /
    Q   W   E   R   T   Y   U   I   O   P
      A   S   D   F   G   H   J   K   L
          Z   X   C   V   B   N   M

• Lens count: 40 (26 letters + 10 digits + 2 base64-extra symbols; no Shift, Space, or Enter lens positions).

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3. plain-bits Allocation

Range	Assignment
PB[0:25]	26 letter lens positions, position-for-position matching Cypher-Input's own 64-Character plain-bits allocation
PB[26:35]	10 digit lens positions (case-invariant)
PB[36:37]	2 base64-extra symbol lens positions: + and /
PB[38:39]	Unused - Cypher-Input's own PB[38:39] carry the 2 Shift keys, which have no corresponding lens position on this board (see §2)
PB[40:63]	Unused - spare plain-bit positions

Provisional pending Quartus pin-planning and PCB layout on the ENC module side. See Design_Spec.md §3 for the common ENC module interface and full J4 zig-zag pin map (Board_Layout.md §1). LED colour and brightness are received entirely as a broadcast from Cypher-Input and never use any plain-bits position - see Design_Spec.md §1.

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4. Board Identification and Custom-Support Switch

• BOARD_ROLE_ID_OUT[3:0] strap value: 0b0111 (Characters + Numbers + Special) by default; 0b1111 (adds Custom, bit3) when SW1 is switched to its custom-support position - see Cypher/Board_Layout.md §4 encoding table and Cypher/Design_Spec.md §3a for the compatibility rule this affects.

SW1 - Custom-Support Switch Circuit

A single user-accessible panel-mount SPDT switch controls BOARD_ROLE_ID_OUT[3] (bit3, Custom):

• SW1 = SPDT, panel-mount, top face - placed in the keyless keepout zone (per Design_Spec.md §1/§2), since this is the only variant with a user-facing configuration control on this board.
• Wiring: common pin -> BOARD_ROLE_ID_OUT[3] (Cypher Left Pair Template bottom row, carried on this board's J1/J2 - see Board_Layout.md §4); one throw -> GND (default position, bit3=0, strap value 0b0111); other throw -> 3V3_ENIG (custom-support position, bit3=1, strap value 0b1111).
• R_CUST (0 Ohm, DNF - Do Not Fit): wired in parallel with SW1's 3V3_ENIG throw, so a user building a permanently-custom lightboard variant can fit this 0 Ohm link instead of relying on the switch position, hardwiring bit3=1 without needing SW1 present at all. Not fitted by default (SW1 alone determines the strap state in the standard build).
• Not part of the JLCPCB PCBA order - SW1 is hand-soldered by the user after the bare-assembled board is delivered (see Design_Spec.md §2 Architecture). R_CUST, if fitted, would be a rear-face (L4) component within JLCPCB's standard SMT pass, but is not populated by default.

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5. Bill of Materials (64-Char Variant-Specific Components)

Variant-specific components for the 64-Character variant. Common components shared across all Cypher-Output variants are listed in design/Electronics/Cypher-Output/Design_Spec.md §11.

RefDes	Specification	MPN	Manufacturer	DigiKey PN	Mouser PN	JLCPCB PN	Alt Supplier + PN	Notes	Footprint Available	Footprint Downloaded	Qty
D1-D40	RGB SMD LED (placeholder - MPN TBD, same part as Cypher-Input, pending confirmation)	TBD	TBD	-	-	-	-	One per lens position (40: 26 letters + 10 digits + 2 symbols); colour/illumination received entirely from the User Settings Module (no local generation); top face - not populated in PCBA, hand-soldered by the user after delivery (see Design_Spec.md §2 Architecture)	-	-	40
R1-R40 (Red)	0402, value TBD pending LED part confirmation	TBD	TBD	-	-	-	-	Red channel current-limit	-	-	40
R1-R40 (Green)	0402, value TBD pending LED part confirmation	TBD	TBD	-	-	-	-	Green channel current-limit	-	-	40
R1-R40 (Blue)	0402, value TBD pending LED part confirmation	TBD	TBD	-	-	-	-	Blue channel current-limit	-	-	40
Q1-Q40	N-channel MOSFET, SOT-23	2N7002K	onsemi (or equiv.)	-	-	-	-	Per-position LED select, gated by that position's decoded plain-bits line; see Design_Spec.md §4	✔	-	40
SW1	SPDT switch, panel-mount	TBD	TBD	-	-	-	-	Custom-support strap switch for BOARD_ROLE_ID_OUT[3]; top face - not populated in PCBA, hand-soldered by the user after delivery; exact supplier part TBD at schematic capture	-	-	1
R_CUST	0 Ohm link, 0402, Do Not Fit (DNF)	TBD	TBD	-	-	-	-	Optional permanent bit3=1 hardwire, in parallel with SW1's 3V3_ENIG throw; not populated by default - see §4	-	-	0 (DNF)

Sourcing status: Q1-Q40 has confirmed sourcing (same part as the 26-Char Classic and 10-Numeric variants). Two items remain pending exact supplier PN confirmation at schematic capture: SW1 (panel-mount SPDT switch part) and R_CUST (any generic 0 Ohm 0402 link, DNF - lowest priority since it is not populated by default).