Pimoroni Stellar Unicorn Simulator
256 RGB LEDs driven the way the hardware drives them
Simulate the Pimoroni Stellar Unicorn online for free: a 16 x 16 RGB LED matrix on a Pico 2 W, nine buttons and a speaker, with thirty-one ready-to-run animations, games and clocks in the gallery.
Free plan · No install, no account · Runs in your browser
Pimoroni Stellar Unicorn at a glance
Pimoroni's square Unicorn: 256 RGB LEDs in a 16 x 16 grid on a 108 mm board, a Raspberry Pi Pico 2 W soldered to the back next to a MAX98357 amplifier and a speaker, nine tactile buttons, two Qw/ST connectors and a phototransistor. There is no display controller: the RP2350 shifts raw column data into a chain of driver chips one row at a time and repeats each row fourteen times with growing on-times. The simulator models that binary code modulation, which is why brightness ramps look right.
- Processor
- Raspberry Pi Pico 2 W (RP2350, dual-core at 150 MHz) soldered on the back
- Memory
- 520 KB SRAM · 16 x 16 RGB LED matrix (256 pixels)
- Emulation
- rp2350js (in-browser)
- Languages
- Arduino C++
- Made by
- Pimoroni · Product page
- Plan
- Free
What you can do with the Pimoroni Stellar Unicorn simulator
The board on the canvas is the real thing as far as your code is concerned: the same pins, the same buses, the same peripherals, wired to the same 100+ sensors, displays and actuators every other Velxio board talks to.
RGB LED matrix
Every pixel is driven the way the hardware drives it, row by row with binary code modulation, so brightness ramps and animations look on the canvas as they do on the wall.
Clickable buttons
The on-board buttons are clickable on the canvas and read on their real GPIOs, active-low as on the hardware.
Speaker
Audio plays through your computer: the exact samples the firmware writes, from tone() to a codec-driven I2S stream.
Arduino C++ sketches
Write a sketch in the Monaco editor with library completion, compile it against the board's own Arduino core and run the real firmware binary. The Serial Monitor is the USB port.
No wiring needed
Every peripheral lives on the board itself, so a project is: place the board, press Run. Wire more when you want to.
What is not emulated
The radio (Bluetooth, Zigbee, Thread or WiFi, depending on the chip) is not modelled. Everything wired to the pins is; the wireless part of a project stays on the bench.
Pimoroni Stellar Unicorn examples
Ready-to-run projects for this board from the gallery. Open one, read the sketch, press Run.
Stellar Unicorn — rainbowPimoroni's own rainbow.py, ported: diagonal rainbow stripes across all 256 LEDs. A and B change the speed, C and D the stripe width, VOL +/- the hue and LUX +/- the brightness; SLEEP freezes it. Click the buttons along the bottom of the board.
Stellar Unicorn — fire effectPimoroni's fire_effect.py, ported: a procedural fire, simulated on a grid two wider and four taller than the panel so the flames have somewhere to come from. LUX + and - adjust the brightness.
Stellar Unicorn — lava lampPimoroni's lava_lamp.py, ported: five metaballs drift around and the liquid takes its colour from how much blobfluence reaches each pixel, hue creeping round as it goes. A reshuffles the blobs, LUX +/- the brightness.
Stellar Unicorn — feature testPimoroni's feature_test.py, ported: a checkerboard and red, green, blue and white gradients cycling one a second, and the panel names whichever of the nine buttons you are holding. Click them along the bottom of the board.
Stellar Unicorn — scrolling textPimoroni's scrolling_text.py, ported: the Hitchhiker's line about how big space is, scrolling across the panel in a 3x5 font over deep blue. LUX + and - adjust the brightness.
Stellar Unicorn — light sensorPimoroni's light_sensor.py, ported: reads the phototransistor on the front's right-hand edge (GP28 / ADC2) and shows how bright the room is, driving the panel's own brightness from it. A turns auto-brightness off, B turns it back on.
Stellar Unicorn — thermometerPimoroni's thermometer_pico.py, ported: the chip's own on-die temperature sensor against a pulsing orb that runs from blue at 15 C to red at 35 C. A starts rainbow party mode, B stops it.
Stellar Unicorn — the matrixPimoroni's numpy/the_matrix.py, ported: HELLO NEO. Green rain, sparkles born in the top half and halving as they fall. LUX + and - adjust the brightness.
Related simulators
Frequently asked questions
- How many Stellar Unicorn examples are there?
- Thirty-one: rainbows, fire, plasma, clocks, games and audio visualisers, each a complete Arduino sketch for the board.
- Do the buttons and the speaker work?
- Yes. The nine buttons are clickable on the canvas and read on their real GPIOs; the speaker plays the samples the sketch sends through the amplifier.
- Is the Pico 2 W's WiFi emulated?
- No. The RM2 radio on the Pico 2 W is not modelled; the matrix, the buttons, the speaker and the light sensor are.
- Is the Pimoroni Stellar Unicorn simulator free?
- Yes. The Pimoroni Stellar Unicorn runs on the free plan: open the editor, place the board and press Run. No install and no account are needed, and Velxio's editor and simulator core are open source under the GNU AGPLv3.
- Which languages can I use on the Pimoroni Stellar Unicorn?
- Arduino C++. The language is switched from the toolbar; the circuit on the canvas stays the same.
Ready to simulate the Pimoroni Stellar Unicorn?
Open the editor, place the Pimoroni Stellar Unicorn from the picker, wire what you need and press Run.
Launch the Pimoroni Stellar Unicorn simulator →