NaoDec Build — Step 8: Controller Unit Hookup

Revision: 1.1 Date: 2026-08-08 Status: Drafted from the author's outline + decisions 1, 2, 4, 5. The controller unit's own internal build is not a step here (see Open Items); this step lands the field cables into it. Rev 1.1 adds §8.3 (GAB8 supply, output rules and indicator reference) from the Wondom GAB8 user manual.

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Purpose

Land every run that came out at node 1 into the controller unit (= Node 0, sitting outside the structure ~2–3 m from node 1), plus the Mac mini and GAB8 on the adjacent table. Verify each landing against the channel map.

Quick Reference — unit contents

Decision 5 vs. the source docs, with each discrepancy flagged:

Not in the unit:

• Mac mini — on the table beside the unit (decision 5); WLED/Art-Net to the LED Master over USB-C→UART, Max/MSP media player, static 192.168.50.2.
• Wondom GAB8 amplifier — at the table/unit area (USB-C from the Mac mini); exact mounting is OI #4.
• Media playback controller — at the chair (Step 6), not here.
• Series-coil PSU + XL4015 buck — the coil subsystem's own isolated 12 V source, kept separate (Step 3).

Node 0 = this unit. The mapping page still draws Node 0 under the base center (the original under-platform plan); the current build has it outside, ~2–3 m from node 1. A future annotation on NaoDec_3D_Vertex_and_Edges_LED_Mapping_Rev1.3.html should note this (index Open Item).

8.1 Cable landing inventory

Everything that converges at node 1 and where it lands:

8.2 Land and verify

1. Build/confirm the controller unit exists and its Config (1 vs 2) is decided before landing (OI #3).
2. Land per the table, one subsystem at a time; keep the three V+ rails isolated (5 V, 12 V/5 A, 12 V/50 A) and the coil rail separate — never bridge V+.
3. Assign and record the C1–C6 ↔ CH2–CH7 map (undocumented today, Step 4 OI #2): note which colored circuit is on which GPIO/strip, both in the unit and back-annotated to the docs.
4. Bond all PSU negatives to the common ground bus (controller doc Note 1).
5. Land the Mac mini USB-C→UART to the Master and the GAB8 USB-C to the Mac mini; sub 3.5 mm to the Mac mini out.
6. Land the GAB8 per §8.3 — all 8 output channels loaded, input polarity verified at the Mini-Fit 2×2, 24 V rail kept isolated from the LED and coil rails.

8.3 GAB8 amplifier — supply, outputs, indicators

Source: Wondom / Sure Electronics GAB8 10 × 50 W USB Codec Input User Manual (UMGAB8-01…06, © 2023). This closes the electrical half of OI #4; mounting stays open.

Supply

No reverse-polarity protection. A reversed input permanently destroys the board and voids the warranty. Verify polarity at the Mini-Fit before the PSU is switched on — a Step 8 check, not a Step 9 one.

The GAB8 24 V is a fourth isolated V+ rail: never bridged to the LED 5 V / 12 V / 50 A rails or the coil rail; only its negative joins the common GND bus. Note the USB-C to the Mac mini already ties the GAB8's ground reference to the Mac mini — if hum shows up at commissioning, suspect that path before the speaker wiring.

Outputs

• Connector: Mini-Fit Jr 2×7, 16 AWG yellow (+) / black (−); the board also carries push-in lever terminals.
• Minimum load 4 Ω (3 Ω only with the supply at ≤20 V; 16 Ω max).
• The manual warns that floating outputs "may lead to EMI issues" — do not energize the amp with channels unloaded. Land all 6 speakers + 2 transducer sets before the 24 V comes up.
• 7.3 / 5.3 configurable; NaoDec uses 8 channels (6 speaker + 2 transducer set).

Control and cooling

• SHDN and MUTE are active-low — shorting either to GND forces shutdown or mute. With no control cable fitted, leave them open.
• The fan is thermostatic, starting at 45 °C heatsink — a still fan at idle is normal, not a fault.
• USB audio input is UAC2.0 7.1, 24-bit / 48 kHz, class-compliant (no driver on macOS).

Indicator reference

The manual ships no LED legend, so this table is the build's reference. Positions were confirmed against the manual's own board renders; behaviour of FAULT / CLIP follows the TPA3244 outputs that drive them.

Amber ≠ fault. On the bench the DAC module's LED sat amber while FAULT and CLIP were both dark — the amplifier was not in protection. Settle the legend at commissioning (§9.6): start playback and record whether it turns green. If it does, amber simply means "idle / no stream" and this row can be made definitive.

Safety

• Never tie the three LED V+ rails, nor the coil rail — isolated throughout; common GND only.
• The GAB8 24 V is a fourth isolated V+ rail — never bridged to the LED or coil rails. Verify Mini-Fit polarity before energizing: the GAB8 has no reverse-polarity protection (§8.3).
• Never energize the GAB8 with output channels unloaded, and never below 4 Ω per channel (§8.3).
• Lockout: keep the upstream mains/PSUs off during landing.
• The 12 V/50 A rail can deliver fault currents that start fires — verify no short before Step 9 powers it.

Release Gate

Open Items

1. Waveshare count — the unit has 3 ESP32-class boards total (Master, Slave, Waveshare); the outline's "3× ESP32 + 1× Waveshare" reads as 4. Confirmed here as 3.
2. Router placement — decision 5 puts it in the unit; the media docs describe it with the Mac mini "in a metal ATX case" ~6 m from the chair. The unit sits ~2–3 m from node 1 — reconcile the distances and the W2 Cat6 length (media doc calls it ~6 m).
3. Controller unit build is not a step — Config 1 (DIN enclosure) vs Config 2 (ATX case) unresolved; it must be bench-built before this step.
4. GAB8 mounting — the electrical spec is settled in §8.3 (24 V, ≥350 W, MEANWELL LRS-350N2-24). Still open: where the amp and its PSU physically sit (in the unit or on the table), and how they land in the mains plan (OI #6).
5. C1–C6 ↔ CH2–CH7 assignment — pick and record it here (see Step 4).
6. Mains distribution — the unit, Mac mini, GAB8 (24 V), subwoofer, and chair USB adapter all need mains; no single mains/CB plan exists.

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