Wiring

Everything connects to the board’s Extended IO header, which also carries +5 V and GND. These are the only GPIOs the WT32-SC01 Plus breaks out; the rest drive the display and touch.

Header pin	GPIO	Connect to
EXT_IO1	10	WS2812 data, through the 330 Ω resistor
EXT_IO3	12	MSGEQ7 OUT (pin 3)
EXT_IO4	13	MSGEQ7 STROBE (pin 4)
EXT_IO6	21	MSGEQ7 RESET (pin 7)
EXT_IO2, EXT_IO5	11, 14	free

The MSGEQ7 board

The circuit is the MSGEQ7 datasheet’s Typical Application, unchanged: 22 kΩ and 0.01 µF into IN, 0.1 µF on VDD, another 0.1 µF on pin 6 (the chip’s internal 2.5 V reference), and the clock set by 200 kΩ from CKIN up to VDD with 33 pF from CKIN down to ground. Keep the two 0.1 µF caps next to the chip. The full schematic is in the repo as hardware/rackglow.pdf, editable in KiCad as hardware/rackglow.kicad_sch.

Audio in

The jack takes a Eurorack-level signal — an FX send, in the reference build — which is around 10 Vpp, while the MSGEQ7 wants roughly 0.1–0.3 Vpp. The front-panel pot does that attenuation: turn it up until the loudest passage just reaches the top band without pinning, then back off slightly. Line level works too, with the pot further up.

Power

The panel and the strips are fed separately — the panel draws very little, the strips draw a lot.

	Feeds	Notes
J3 · Eurorack 10-pin bus header	the panel	+5 V and GND from the case’s bus board
J4 · 5 V screw terminal	the panel, the strips, or both	An external supply

The reference build uses two supplies: the case’s Eurorack bus powers the panel through J3, and a second 5 V supply drives the LED strips alone. One supply through J4 works too, if it is sized for the strips plus the board.

Caution

Don’t run the strips from a Eurorack 5 V rail. 145 LEDs at full white can ask for several amps, far more than those rails are built for. Give the strips their own 5 V supply, sized for roughly 60 mA per LED at full white, and share ground with the board.

What it looks like if you get it wrong: oscillator pitch drifting as you turn the lights up. The strips load the rail, the rail sags, and everything running off it goes with it. That symptom is what put the second supply in this build — and it reads as a synth fault, not a lighting one.

Strip layout

Strips are daisy-chained on the one data line and treated as equal-length rows. Alternate strips run in opposite directions (serpentine), which is how they chain naturally behind a rail. You set the strip count and LEDs per strip in the web UI after installing.