Final Project¶
ERKXOSUTYUN (Dialogue)¶
My final project is ERKXOSUTYUN (Dialogue) — an interactive outdoor light object built around the contrast between light and darkness, day and night. During the day it exists as a quiet sculptural form, emphasizing geometry, materials, and the interaction between sunlight and the structure itself. At night, it “awakens” — internal LED lighting activates and the object begins actively responding to its environment, with light becoming its primary medium of communication.
What does it do¶
An LDR sensor continuously measures ambient light levels and determines whether it is day or night: when darkness falls, the LED lighting system automatically activates, and as daylight increases the lights turn off again. A DHT11 sensor provides temperature and humidity readings, and a DS3231 real-time clock module supplies accurate time data — all of it displayed in real time on MAX7219 LED matrix displays mounted behind a mirrored, light-diffusing surface.
The whole system runs on a custom PCB built around a Seeed Studio XIAO RP2040, housed inside a metal structure that also supports the lighting and acrylic diffusion panels. Beyond its technical function, the object is meant as a conceptual exploration of natural cycles — translating environmental data into a visual “dialogue” between technology, the environment, and the viewer.
Interesting work done by others¶
- BruumRuum! (Artec3 / David Torrents, Barcelona) is an interactive public installation that responds to city noise and human voices using LED lighting, changing color and movement depending on sound intensity — this was the main reference that showed how light can become a medium for communication rather than simply illumination.
- Proximity Reactive Flower Lamp (GlowSense), a Fab Academy project, uses a proximity sensor and NeoPixel LEDs to respond to human presence by changing color and brightness depending on distance — useful for thinking through how sensor input maps to visual output.
Materials and accessories used¶
| Qty | Description | Price | Origin |
|---|---|---|---|
| 1 | MAX7219 display | 5 $ | Temu |
| 1 | Voltage regulator | 3 $ | Temu |
| 1 | 12V LED strip | 5 $ | Our Lab |
| 1 | DS3231 RTC module | 4–6 $ | Temu |
| 1 | DHT11 sensor | 3 $ | Temu |
| 1 | Photoresistor (LDR) | 2–3 $ | Temu |
| 1 | Power supply | 7–8 $ | Our Lab |
| 1 | Wires and connectors | 2–3 $ | Our Lab |
| 1 | Metal sheet | 40 $ | Our Lab |
| 1 | Mirror | 13 $ | Our Lab |
| 1 m | Metal pipe | 1 $ | Our Lab |
| 1 m | Plastic film | 4 $ | Our Lab |
| 1 kg | PLA / PETG filament | 32.99 $ | Our Lab |
| 1 m² | Acrylic sheets | 18 $ | Our Lab |
| 1 | XIAO RP2040 microcontroller | 6.23 $ | Our Lab |
| 1 | PCB board | 9.05 $ | Our Lab |
| - | MOSFETs, resistors, capacitors, other components | 3 $ | Our Lab |
| Total | ~165 $ |
Concept and Early Sketches¶
The project started in Week 1 as a sketch and concept description of an interactive outdoor object responding to the cycle of day and night. The original concept also imagined the object running entirely on solar power, with a battery and charge controller storing daytime energy for nighttime use — a feature that didn’t make it into the final build, which instead runs from a standard 12V power supply, but the core day/night light-and-darkness concept carried through to the finished piece.
In Week 2, the idea was developed further with 2D and 3D design work to visualize the object’s structure before any hardware was involved.
Choosing the Sensors¶
In Week 4, I worked through embedded programming exercises that fed directly into the sensor choices for this project — establishing how a microcontroller could read environmental input and translate it into a controlled response, which became the basic input → processing → output logic that the whole object is built on.
Electronics Design and PCB Redesign¶
The electronics evolved significantly over the course of the project. The original PCB was designed around I2C displays, with SDA and SCL connections broken out for that purpose. After comparing display options, I decided MAX7219 LED matrix displays were a better fit — more compact, simpler to control, and more visible for an outdoor installation — which meant the board needed a full redesign.
In Week 9, I replaced the I2C connections with the DIN, CLK, and CS lines the MAX7219 needs, and added extra capacitors on the power lines to reduce electrical noise from the displays and LED lighting. The final board integrates the XIAO RP2040, the LDR input, DHT11 and DS3231 connections, MOSFET-based LED control, the MAX7219 display outputs, and voltage regulation — milled, soldered, and tested as a single finished PCB.
Sensors and Output Integration¶
In Week 10, the primary sensors and displays were integrated and tested together for the first time. The DHT11 provided temperature and humidity, the DS3231 supplied time data, and — since only two MAX7219 displays were available at that stage — temperature and humidity alternated on one display every 15 seconds while the second display continuously showed the time. This confirmed the full pipeline from sensors through the microcontroller to the displays before moving on to final assembly.
System Integration and Enclosures¶
Week 15 covered the design and fabrication of dedicated enclosures for each major electronic module — the main board, the power supply, the voltage regulator, and the display mounting structure — so that every component could be safely housed, properly ventilated, and cleanly wired rather than left as loose, exposed electronics.
The main board enclosure was modeled in FreeCAD directly around a STEP export of the actual PCB, with mounting tabs, ventilation holes, and cable-routing openings built in, and a Fab Lab Armenia logo cut into the lid for later epoxy infill. The power supply and voltage regulator each got their own enclosures sized to their real dimensions, and a separate mounting structure was designed for the three MAX7219 displays so they could be aligned precisely on the acrylic panel behind the mirror.
Metal Structure¶
The metal frame — one of the largest and most demanding parts of the project — began as sketches and CAD models defining the object’s overall geometry and proportions, then moved through CNC machining and manual cutting, bending, alignment, and welding to reach its final form. The frame had to simultaneously provide enough mechanical strength for outdoor use, support the lighting system, contain the electronics, and leave proper visibility for the displays.
After welding, the curved sections were formed and fitted, and acrylic sheets were heat-formed to match the structure’s geometry, then covered with a diffusion film to control transparency and shape the light effect. The LED lighting was installed inside the frame before the second side was closed up the same way.
Final Assembly¶
Week 16 explored metal laser cutting as a separate Wildcard Week fabrication process — a sketch of the upper part of this final project’s form was cut from metal as an exercise in that process, but this particular piece doesn’t attach to or appear on the finished object itself.
The actual final assembly involved fixing all internal components in place with silicone adhesive and screws, running a full system test to confirm the electronics, sensors, displays, and lighting all worked correctly, and only then installing the mirrors — front first, then the sides, for easier access during the rest of the assembly.
The LCD mounting area:
And the MAX7219 displays in their final position:
What Worked, What Didn’t¶
The electronic subsystem performed reliably end to end: sensor communication was stable, the displays worked correctly, and the LED lighting responded accurately to changes in ambient light. Most of the real difficulty in this project was mechanical rather than electronic — several sections of the metal structure needed additional welding and alignment correction to keep the geometry accurate, which took considerably more iteration than the electronics side did.
Files¶
License¶
YERKXOSUTYUN © 2026 by Ani Petrosyan is licensed under CC BY-NC-ND 4.0.
I have chosen the Creative Commons CC BY-NC-ND 4.0 license for this project after reviewing the available Creative Commons licenses.
This license allows others to copy and share the project, provided that proper credit is given to the original author. However, it does not allow commercial use, modification, or the creation of derivative works.
I selected this license to protect the originality and integrity of my project, preserve my copyright, and prevent unauthorized modifications or commercial use.