The Most Random Electronic Dice Yet


If you’ve written a great library to generate random numbers with a microcontroller, what’s the first thing you would do? Build an electronic pair of dice, of course.

[Walter] created the entropy library for AVRs for a reliable source of true random numbers. It works by using the watchdog timer’s natural jitter; not fast by any means but most sources of entropy aren’t that fast anyway. By sampling a whole lot of AVR chips and doing a few statistical tests, it turns out this library is actually a pretty good source of randomness, at least as good as a pair of dice.

The circuit itself uses two 8×8 LED matrices from Adafruit, an Arduino, and a pair of buttons. The supported modes are 2d6, 2d4, 2d8, 2d10, 1d12, 1d20, a deck of cards, a single hex number, a single 8-bit binary number, or an eight character alphanumeric password. It’s more than enough for D&D or when you really need an unguessable password. Video demo below.

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We’ll take the fries.


We’ve all been there; hardest decision we’ve ever had to make. College and debt or freedom but no career? Start a family or live out alone? The number 2 with a small shake or side of fries?!

[Leon] sent in his random number generator, oddly enough not to just generate a number, but help us through with those life altering decisions. Using a noise diode like setup he’s able to generate random bits, which an ATtiny24 then converts and displays on a 7 segment LED. His generator also has the ability to set upper and lower limits. Seems like an awful lot of work to avoid the freedom of choice paradox, but we enjoyed the project none the less. Check out a video after the break. [Read more...]