General purpose MCUs built in to LEDs emulate candle flicker
Tiny microcontrollers are now so cheap they’re being built directly into individual LEDs to simulate candle flicker, illustrating how “free” compute has become and how it increasingly replaces simple analog circuits. Commenters explore what counts as a “computer,” note that modern MCUs often have far more capability than early desktop CPUs, and point to similar uses in smart bulbs, RFID tickets, greeting cards, and magazine inserts. Alongside the technical curiosity and hacking potential, many raise concerns about waste and safety, especially around disposable electronics like vapes and LED candles with non‑recyclable lithium batteries.
Computers as Disposable Components
- Many comments note that ultra-cheap MCUs realize old predictions that computers would be cereal-box prizes and thrown away.
- Examples given: RFID transit tickets, musical greeting cards, video-playing magazine inserts, LED candle dies, smart bulbs, and cheap microcontrollers costing a few cents.
- Some argue we’ve long passed the point where the silicon compute core is “free” and packaging/testing costs more than the logic itself.
Microcontrollers vs Microprocessors
- Debate over what counts as a “computer” and how to distinguish MCUs from microprocessors.
- Historical CPUs without MMUs are cited; others say the real distinction is integrated program memory and peripherals, not MMUs.
- Consensus: the terms are now mostly marketing; capabilities overlap heavily.
Candle Flicker Implementations
- Older flicker LEDs allegedly reused audio greeting-card ASICs; evidence and recordings from earlier forums and videos are linked.
- Some devices used simple counter+ROM tables with precomputed brightness patterns because PRNGs looked “wrong.”
- The examined LED appears to contain a general-purpose 8‑pin MCU die with memory, logic, and analog blocks; exact model is debated but many think it’s a PIC‑style clone.
- Other projects: LFSR-based flicker code, more advanced multi-LED “flame” optics, and commercial high-end flameless candles with complex R&D.
Disposable Electronics & Environmental Concerns
- Strong criticism of disposable vapes, LED gadgets, and “single-use” Li‑ion devices.
- Points raised: fire risk in waste streams, lithium/resource waste, and lack of recycling or reuse pathways.
- Some argue individual cells in vapes are commodity Li‑ion and not a significant fraction of global lithium use; others counter with large sale volumes (e.g., millions per week in one country).
- Calls for regulation (e.g., bans, deposit/core charges) and for banning non-rechargeable Li‑ion products.
Hackability, Tooling, and Reuse
- Frustration that most embedded MCUs in consumer goods are OTP or locked and not practically reusable.
- Counterpoint: modern ARM MCUs with standard debug interfaces, cheap dev boards, and open tools have dramatically lowered entry costs; sophisticated work can be done with tens of dollars of gear.
- Some still lament the difficulty of reprogramming “found” microcontrollers versus buying known modules (ESP-class boards, etc.).
Safety, UX, and Aesthetics
- Split opinions on LED candles: some see them as tacky; others value safety, air quality, automatic timers, and low fire risk.
- Desire expressed for more realistic flicker algorithms and for recreating classic incandescent blinking light behaviors.