Hardware: Longboi reference build

The longboi is led-ticker’s reference build for widescreen single-row displays: a Raspberry Pi 5 driving four Muen P2 128×64 indoor LED panels chained horizontally for a 512×64 canvas — roughly 100 cm × 13 cm overall. The MLB scoreboard layout and the hires font pipeline were developed against this build. It sits on top of a bookcase and appears on camera during meetings, which is why the reference config is tuned to minimise flicker in video.

At a glance

Raspberry Pi 5
4× Muen P2 128×64 LED panels chained left-to-right = 512×64 physical canvas
~100 cm × 13 cm overall (four 256 mm × 128 mm panels end-to-end)
default_scale = 4 — every logical pixel becomes a 4×4 block on the real panel; drawing logic stays at the standard 16-tall logical canvas
No pixel_mapper_config needed — a single horizontal chain with chain_length = 4 is enough
Same Docker image as the bigsign; the rgbmatrix library detects the SoC at runtime

Bill of materials

Component	Quantity	Notes
Raspberry Pi 5	1	4 GB is plenty. A microSD card and a USB-C supply for the Pi itself.
Muen P2 128×64 indoor LED panel	4	HUB75 panels, 256 mm × 128 mm each, P2 (2 mm) pitch. FM6126A driver IC — `panel_type = "FM6126A"` is required in config.
Adafruit RGB Matrix Bonnet	1	Sets `hardware_mapping = "adafruit-hat"` in the config. The HAT works equivalently.
Mean Well LRS-200-5 5 V 40 A supply	1	200 W headroom for four P2 panels. Wire directly to panel power inputs — do NOT power panels off the Pi.
16-pin IDC ribbon cables	3+	One between each panel in the chain. Most panels ship with a short cable; buy extras for the longer runs.
Power distribution wire / pigtails	1+	Each panel has its own 2-pin power input. Daisy-chain from the PSU or use a busbar.

Total cost (rough): ~$300–400 USD. The PSU and four panels are the dominant line items. Cross-check current pricing before ordering.

Assembly notes

E-pin soldering (required for 64-row panels)

Solder a jumper wire from GPIO 8 to the E pad on the Adafruit bonnet. Follow the Adafruit RGB Matrix Bonnet setup guide for pad location and soldering instructions.

This is the one step not covered by the panel datasheet or the rgbmatrix README — everything else (IDC cables, power wiring) is standard HUB75.

Panel init sequence (`panel_type = "FM6126A"`)

The Muen P2 panels use the FM6126A (or compatible) driver IC, which requires a proprietary initialization sequence at startup. Set panel_type = "FM6126A" in the config. Without it the driver powers up in a bad state and the first scan lines render with the wrong brightness or color.

Color channel order (`led_rgb_sequence = "BRG"`)

These panels wire the HUB75 R/G/B lines in a non-standard order (G → Red LED, R → Blue LED, B → Green LED). Set led_rgb_sequence = "BRG". Without it all colors are wrong.

Config snippet

The minimal [display] block for the longboi, tuned for camera use (pwm_bits = 7 and limit_refresh_rate_hz = 100 reduce flicker visible in video):

[display]
rows = 64
cols = 128
chain_length = 4
brightness = 60
default_scale = 4
hardware_mapping = "adafruit-hat"
panel_type = "FM6126A"        # FM6126A init sequence — required for Muen P2
led_rgb_sequence = "BRG"      # Muen P2 color channel order
gpio_slowdown = 5             # Pi 5 RIO backend (default); raise if flicker persists
pwm_bits = 7                  # 7-bit PWM: tuned for camera; default is 11
limit_refresh_rate_hz = 100   # caps refresh to stabilise image on camera

Tuning knobs

Setting	Value	Why
`gpio_slowdown`	`5`	Pi 5 with the default RIO backend needs higher slowdown than Pi 4. Raise to 6+ if flicker persists.
`row_address_type`	`0`	Must remain `0` (the default) with the RIO backend. Setting `1` breaks display output.
`pwm_bits`	`7`	7-bit PWM keeps the refresh rate high while limiting flicker visible in video. Default is 11.
`limit_refresh_rate_hz`	`100`	Caps the refresh to a stable rate for camera capture. Remove if not on camera.
`panel_type`	`"FM6126A"`	Required FM6126A init sequence; without it the bottom half of panels is garbled.
`led_rgb_sequence`	`"BRG"`	Muen P2 non-standard color wiring. Without it all colors are wrong.
`default_scale`	`4`	Maps the 16-tall logical canvas to the 64-tall physical panel.

Photos

Photos coming soon.

Full display on bookcase (form factor)
E-pin solder joint on the bonnet (the critical assembly step)
Back of panels showing IDC cable routing