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Jagi Natarajan created Phyllotaxis, a physical LED display whose cells follow the spiral pattern found in sunflower heads and other plants. An STM32 board analyzes sound from a digital microphone and uses the audio to shape the display’s light patterns. The source describes a personal build; it does not provide a release date, price or availability.
Designer and maker Jagi Natarajan has built Phyllotaxis, an 89-LED display arranged in cells derived from the spiral pattern seen in sunflower heads and other plants. An STM32 microcontroller analyzes sound picked up by a digital microphone and changes the LEDs’ patterns, turning a mathematical study of plant growth into a working physical object.
Natarajan’s project began with a computer-generated pattern: points placed along a radius and rotated by increasing multiples of the golden ratio. Applying Voronoi tessellation to those points produced irregular, seed-like cells. Natarajan exported their edges from a Processing sketch and used CadQuery and FreeCAD to create printable geometry, including LED openings, walls and a separate faceplate. The enclosure was divided into four sections to fit the maker’s 3D printer.
The printed assembly holds 89 RGB addressable LEDs, with translucent mulberry paper used to diffuse their light. Natarajan soldered the LEDs and connected them to a spare STM32 Blackpill board, writing a NeoPixel driver that uses SPI. The controller stores each LED’s position so the program can calculate patterns from its radius and angle, including a sine wave that pulses outward from the center.
For audio response, Natarajan added an INMP441 I2S digital microphone. The STM32 runs audio analysis using the ARM CMSIS library, with automatic gain control and frequency-band splitting to estimate energy across different parts of the sound. Natarajan says the resulting patterns were tuned through experimentation. The project report describes the electronics as a work in progress: the controller and microphone were mounted on perfboard and placed in a printed enclosure, but the electronics were still prone to noise.
From Plant Geometry to Light
Phyllotaxis shows how a pattern studied in code can guide both the shape and behavior of a physical object. The point placement determines the display’s cell layout, while the coordinates of those cells give the software a way to calculate radial light patterns. Geometry and animation are tied to the same underlying arrangement.
The audio feature adds a second layer: the display responds to sound captured in its surroundings rather than relying only on fixed test patterns. Natarajan presents the build as an individual experiment, not a commercial product or a general-purpose audio device. Its practical significance is the documented combination of custom fabrication, embedded audio processing and addressable LEDs in a non-rectangular display.
How the Sunflower Pattern Works
Phyllotaxis describes the arrangement of leaves, seeds or other plant structures around a growing point. In Natarajan’s digital version, points are spaced along a radial line and rotated by a progressively increasing angle related to the golden ratio. That produces a spiral-like distribution; the source says the points already resembled a sunflower before Natarajan applied Voronoi tessellation to form cells.
Natarajan had previously built a rectangular NeoPixel matrix in high school and wanted to try a different shape. The project moved from a Processing sketch to CAD models and printed parts, then to firmware for LED patterns. A bamboo cutting board was routed into a circular mount, and a foot-switch-style control was added to the printed electronics box. Natarajan describes the display reacting to Jon Hopkins’ track “Neon Pattern Drum” during testing.
Hardware Status and Release Details
The supplied project report cuts off while describing noise in the electronics, so it does not establish whether Natarajan later resolved the issue or completed a more robust controller assembly. It also gives no publication date, cost, dimensions, build files, parts list or availability information. No commercial release is described, and the report does not specify how the system behaves across different sound levels or environments.
A Build With Open Questions
The source does not announce a planned launch, follow-up release or next milestone. The immediate open engineering issue in the supplied text is the noise affecting the electronics. Further details from Natarajan would be needed to confirm whether that was fixed, whether the design files are available to others, and whether the display remains a one-off personal project.
Key Questions
What is Phyllotaxis?
Phyllotaxis is Natarajan’s handmade LED display. Its cells are based on a spiral arrangement inspired by patterns found in sunflower heads and other plants.
How does the display react to sound?
An INMP441 digital microphone captures audio. An STM32 board analyzes the signal, including energy in multiple frequency bands, and uses the results to influence LED patterns.
How many LEDs does it use?
The project report says the display has 89 RGB addressable LEDs, one fitted into each cell.
Can people buy or build the display?
The supplied report does not state that Phyllotaxis is for sale or provide a complete parts list or fabrication files. Its availability for purchase or replication is not established by the source.
Source: hn
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