HUB75 Wiring Guide

Physical wiring for different SpojBoard hardware variants.

Automatic Pin Mapping

Good news: The firmware automatically adjusts pin mappings based on your hardware variant. Use standard HUB75 cables without modifications — just plug and play!

The firmware detects whether you're using a MatrixPortal S3 or generic ESP32-S3 and configures pins accordingly.

MatrixPortal ESP32-S3

The MatrixPortal has a built-in HUB75 connector. Simply plug your panel's cable directly into the board — no wiring required.

Internal Pin Mapping

HUB75	GPIO	HUB75	GPIO
R1	42	A	45
G1	40	B	36
B1	41	C	48
R2	38	D	35
G2	37	CLK	2
B2	39	LAT	47
E	21	OE	14

ESP32-S3 N8R2 DevKit (Generic)

For generic ESP32-S3 boards, use a HUB75 cable with breakout to dupont pins. The firmware automatically handles pin mapping — just use standard HUB75 wiring.

Rainbow Cable Wiring

#	Color	HUB75	GPIO
1	Brown	R1	42
2	Orange	G1	41
3	Yellow	B1	40
4	Green	GND	GND
5	Blue	R2	38
6	Purple	G2	39
7	Gray	B2	37
8	White	E	21
9	Black	A	45
10	Red	B	36
11	Orange	C	48
12	Yellow	D	35
13	Green	CLK	2
14	Blue	LAT	47
15	Purple	OE	14
16	White	GND	GND

Standard HUB75 Pinout Reference

Top Row (Pins 1-8):
┌────┬────┬────┬────┬────┬────┬────┬────┐
│ R1 │ G1 │ B1 │GND │ R2 │ G2 │ B2 │ E  │
└────┴────┴────┴────┴────┴────┴────┴────┘

Bottom Row (Pins 9-16):
┌────┬────┬────┬────┬────┬────┬────┬────┐
│ A  │ B  │ C  │ D  │CLK │LAT │ OE │GND │
└────┴────┴────┴────┴────┴────┴────┴────┘

Power Connections

SpojBoard draws 0.3-0.7A during normal operation, with transient peaks up to 1.6A during WiFi connection, OTA updates, or boot.

MatrixPortal S3

Connect panels to MatrixPortal's screw terminals (5V/GND)
Connect USB-C to MatrixPortal (5V 2A+ adapter)
USB-C powers both MatrixPortal and panels via screw terminals

ESP32-S3 N8R2

LED panels require their own 5V power supply (2A+ minimum) via screw terminals
The same PSU can also power the ESP32-S3 (connect to ESP32's 5V/GND pins)
Or power ESP32 separately via USB (ensure common GND with panels)

Power Topology Comparison

MatrixPortal S3 (Serial)

USB-C → MatrixPortal → Panels
        (passes power through)

USB-C powers the board, which passes power to panels via screw terminals.

ESP32-S3 N8R2 (Parallel)

        ┌→ ESP32-S3
PSU 5V ─┤
        └→ Panels

ESP32-S3 cannot pass through enough current. PSU powers both in parallel.

Power Supply Recommendations

Supply	Rating	Suitability
USB-C Wall Adapter	5V 2A (10W)	✅ Adequate
USB-C Wall Adapter	5V 3A (15W)	✅ Recommended
USB-C Wall Adapter	5V 1A (5W)	❌ Insufficient
Screw Terminal PSU	5V 2-3A	✅ For ESP32-S3 N8R2

Never power the panels from the ESP32's 5V pin — it cannot supply enough current and will cause resets.

Why Lower Than Specs?

Published HUB75 specs cite 4-6A at full brightness with all white LEDs. SpojBoard's real-world usage is much lower:

Text displays use far fewer LEDs than solid colors
Mixed colors draw less than white
Default brightness (90/255 = 35%) reduces power
Most pixels are black (off) in typical display

Troubleshooting

Colors are wrong (generic ESP32-S3)

Verify wires connected as documented
Check all wires firmly connected
Ensure common ground between ESP32 and panel power

Panel doesn't light up

Check panel has separate 5V power connected
Verify GND connection between ESP32 and panel
Check all 16 signal wires connected

Flickering or artifacts

Ensure common ground between ESP32 and panel
Check for loose connections
Verify power supply provides sufficient current