Pseudonymous maker “Maker’s Enjoyable Duck,” hereafter merely “Duck,” has demonstrated methods to reverse engineer the standard kitchen timer so as to add a bit extra performance — designing a drop-in Arduino-compatible alternative PCB for the actual mannequin focused.
“Just a few years in the past I purchased this kitchen [timer], or egg timer as individuals are calling it, and I just lately visited the identical retailer and noticed precisely the identical one on the cabinets,” Duck explains. “I assumed it will be good to manage the LCDs and buttons on this issues for my very own tasks, as a result of they’re simply round €2 [$2.17], they’re quite simple gadgets, and perhaps it is the rationale for his or her success.”
Whereas the low-cost timers are solely useful as-is for cooking eggs good, Duck had different concepts in thoughts: changing the widespread 2×16 LCD in lots of tasks with an all-in-one gadget boasting display screen, buttons, housing, and even a magnet on the rear for ease of mounting. That, although, means changing the electronics — which, in flip, means reverse engineering the gadget’s interior workings.
Constructed to a particular finances, the LCDs on the timers are pushed instantly fairly than by way of an on-board driver chip. “In case you see an affordable digital gadget with an LCD like this one,” Duck explains, “there’s a very excessive probability that it has this sort of LCD. It will not have a driver on it, simply two glasses stacked along with LCD fluid in between. On the contact factors there’s a ‘zebra strip’ the place you ship your indicators out of your microcontroller.”
To regulate the display screen from a distinct microcontroller, Duck floor off the unique — hidden underneath a black blob of epoxy — and related wires to the “zebra strip” contacts, prepared for breadboard experimentation. An Arduino sends indicators which management every phase of the LCD panel, handed by a less complicated resistor-based voltage divider and toggled between pins to simulate the alternating present required to drive the show.
Its microcontroller eliminated by grinding, the timer board is mapped utilizing an Arduino. (📷: Maker’s Enjoyable Duck)
Having mapped the pins and their corresponding show segments, Duck may design a alternative board — combining a Microchip ATtiny13A or Espressif ESP12E microcontroller with a Shenzhen Titan Micro Electronics TM1621D LCD driver. An Arduino sketch loaded onto the microcontroller permits the buttons to be learn and the show to be pushed — even to the purpose of printing messages made up from “supported letters” on the show.
Design recordsdata for the PCB and supply code for the firmware, for each the customized show board and for tracing LCD segments from an Arduino, have been uploaded to GitHub underneath an unspecified license; extra data is accessible within the video embedded above and on Maker’s Enjoyable Duck’s YouTube channel.