Tag Archives: natural jitter

Video: Electronic dice go random with AVR



A Maker named Walter recently created an entropy library for Atmel AVR microcontrollers (MCUs) to ensure a reliable source of truly arbitrary numbers.

As HackADay’s Brian Benchoff reports, the electronic dice generate random numbers by taking advantage of the watchdog timer’s natural jitter.

“[This isn’t] fast by any means but most sources of entropy aren’t that fast anyway,” Benchoff explains. “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.”

According to Benchoff, the circuit itself employs a pair of 8×8 LED matrices from Adafruit, an Atmel-based Arduino board and a pair of buttons.

Supported modes (11 total)?

  • 2d6
  • 2d4
  • 2d8
  • 2d10
  • 1d12
  • 1d20
  • Deck of cards
  • Single hex number
  • Single 8-bit binary number
  • 8 character alphanumeric password

Interested in learning more? You can watch the video above or check out the project’s official page here.