🛠 Mur de LEDs et panneaux HUB75 : OctoWS2811, WS2812Serial et SmartMatrix sur le 4.1

Objectives

The Teensy 4.1 is the reference for LED walls thanks to three DMA engines: OctoWS2811 (refreshes 1,920+ LEDs at 30 Hz and, specific to the 4.1, on any number of parallel pins — the 8-pin limit of Teensy 3.x is removed), WS2812Serial (up to 8 non-blocking DMA instances on serial ports) and SmartMatrix (HUB75 panels from 32x16 up to 128x64 with the SmartLED Shield v4/v5). All this with a CPU that remains largely free for animation.

Hardware

• 1 Teensy 4.1 + micro-USB data cable
• WS2812B strips with dedicated 5 V power supply (data remains at 3.3 V: the Teensy powers the data, not the LEDs)
• For HUB75: a SmartLED Shield v4 or v5 and a compatible panel

Key Points

• OctoWS2811 reserves the pins and timers it controls — notably the QuadTimer4 channels, reserved by the library: do not use them elsewhere.
• WS2812Serial is non-blocking: each instance is a dedicated DMA serial port, ideal when animation is running elsewhere.
• SmartMatrix on the 4.1 exploits the nascent Pixel Processing Pipeline — PJRC still describes it as very experimental; the library itself is mature.
• The absolute electrical rule: Teensy pins tolerate only 3.3 V; WS2812 data generally accepts the 3.3 V level as a high threshold, but in case of a finicky strip, a 3.3 V → 5 V level shifter on the data line is the clean solution.

Procedure (OctoWS2811)

1. Install the library via the Library Manager or https://www.pjrc.com/teensy/td_libs_OctoWS2811.html.
2. Declare OctoWS2811 leds(ledsPerStrip, displayType, octoPins) with your parallel pins.
3. leds.begin then draw with leds.setPixel(index, color) and leds.update — a single DMA update refreshes all strips.
4. For the complete video example (1920 LEDs), follow the OctoWS2811 page on PJRC.

Procedure (SmartMatrix)

1. Mount the SmartLED Shield v4/v5, set the panel resolution in SM_config.h (the 4.1 accepts up to 128x64).
2. GIF animation examples and FastLED compatibility provided by the library.

Expected Verification

Entire strips animate at 30 Hz or more without glitches while Serial and your sensors keep running: this is the signature of DMA transfers. The die temperature remains reasonable (see the memory tutorial to monitor it).

Common Errors

• LED power taken from the Teensy's 3.3 V: output reserved for the onboard regulator, 250 mA max — an LED wall is powered by external 5 V, with grounds connected.
• Forgetting the series resistor (~330 Ω) on the data line and the capacitor on the first strip's power supply.
• Confusing the three libraries: OctoWS2811 = synchronous parallel pins; WS2812Serial = DMA serial ports; SmartMatrix = HUB75 panels.
• Following old JTAG wiring: JTAG pins moved in June 2022 on the 4.1 — check your board's date before following an old guide.