Mononymous maker Tim has found a shock inclusion within the LED of an inexpensive flickering candle LED dwelling accent: a useful clone of the Microchip PIC12F50x eight-bit microcontroller.
“I used to be not too long ago tipped off to an upgraded [LED tea-light] that features a timer that turns off the candle after it was energetic for 6h and turns it on once more 18h later, e.g. once you flip it on at 7PM on in the future, it could keep energetic until 1AM and deactivate itself till 7PM on the following day,” Tim explains of the characteristic which piqued his curiosity. “Appears fairly helpful, really. The query is, how is it carried out? I purchased a few these tea lights and took a better look.”
With solely an LED, swap, and battery, this timer-capable tea-light hides a stunning secret: a hidden microcontroller. (📷: Tim)
Externally, the timer-capable lights appeared like some other LED-based tea-light candle: a white wax-like plastic shell and a plastic diffuser performing because the flame. Inside was a single compact LED linked to a battery by a swap — no different circuitry, and the swap merely moved one leg of the LED to make and break the contact with the battery.
What an off-the-cuff inspection did not reveal was any type of microcontroller, or perhaps a timer. A glance by a microscope on the LED, although, turned up one thing curiosity: the die of an built-in circuit which appeared over-engineered for being a easy LED. “What’s curious in regards to the IC,” Tim explains, “is that it relatively giant, has loads of unused pads (three out of eight used) and appears to have comparatively small constructions.
“There are rectangular common areas that appear like reminiscence, there’s a giant space within the heart with small random wanting construction, wanting like synthesized logic and a few half that appear like hand-crafted analog. Might this be a microcontroller?”
Energy evaluation suggests the hidden microcontroller runs at full pace even whereas sleeping. (📷: Tim)
Recognizing the pad format, Tim realized the chip was a useful clone of the Microchip PIC12F50x — a low-cost one-time-programmable eight-bit microcontroller, relatively than an application-specific built-in circuit (ASIC) designed for the duty. “Within the yr 2023, it seems that investing improvement prices in a candle-flicker ASIC is not essentially the most economical choice,” Tim surmises. “As an alternative, ultra-inexpensive eight-bit OTP microcontrollers appear to be taking up low-cost electronics in every single place.”
Tim’s full write-up is offered on his weblog, together with observations on a surprisingly excessive present consumption which could possibly be improved with a transfer to a sleep-mode microcontroller.
