Builder constructed a physical Conway’s Game of Life on a 17x17 matrix of NKK JB15LPF-JF illuminated switches with a custom PCB and AVR128DA64 MCU.
Key Takeaways
NKK JB15LPF-JF switches at ~$3 each account for the bulk of cost; 289 units across the 17x17 grid make this an intentionally expensive build.
Multiplexed row scanning at 1/17th duty cycle (~6%) forces 150mA per LED; DMN2056U n-channel and DMG2301L p-channel MOSFETs handle current the MCU GPIO cannot source directly.
Firmware safety: screen redraw is fully decoupled from game state changes, which happen only during a brief LED-off “blackout” window to prevent sustained high current from damaging diodes.
A 15ms watchdog timer forces MCU reboot if the event loop stalls, protecting display hardware from stuck-on rows at 150mA.
Speed control is a 10kΩ potentiometer on an ADC pin; simulation runs 0-10 Hz, and each switch press pauses evaluation for 2 seconds to allow multi-cell drawing without adjusting the knob.
Hacker News Comment Review
No substantive discussion in this thread; the single comment redirects to a prior HN submission that generated 92 comments.
Notable Comments
@mitchbob: flags a recent 92-comment HN discussion of the same project at a separate submission.
