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Light Up All 16 LEDs to Solve This PCB Puzzle

Light Up All 16 LEDs to Solve This PCB Puzzle


Last year, David-Johnson Davies came up with a breadboard and microcontroller game featuring five LEDs and buttons. This year, he’s following it up with a 16 LED/16 button game.

It runs on a PCB equipped with an ATtiny404 as the controller, though you can use a ‘204 or other ATtiny chips depending on what’s available.

When power is first connected, you're presented with a random pattern of LEDs that have to be turned on to solve the puzzle. As DJD describes the gameplay: “Each button toggles the state of the LED above it, but it also has the side effect of toggling other LEDs on the matrix, so getting all the LEDs to turn on takes a bit of logical thinking.” He continues that, “You can solve the puzzle by pressing one button at a time; you don't need to press combinations."

The buttons and LEDs are wired up in a matrix, with an additional diode added for each LED. This allows the button to act as an input without shorting lights when they're meant to be illuminated.

While a clever setup, the wiring itself doesn’t offer any clues as to how the puzzle is solved, though perhaps a close examination of the code could yield some clarification.

The circuit goes to sleep if nothing has been pushed for 30 seconds, sipping roughly 1µA of current until it wakes again. Upon full power-up, you’re presented with the same state of gameplay as before, so you’ll have to figure it the initial puzzle out – or actually pull the power. Once you've solved the puzzle, the LEDs flash and a new random puzzle starting position is displayed, waiting for your solution.

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