Zen Dice II

Zen Dice II

Zen Dice II
A truly random electronic dice and random number generator, times two.

Zen Dice II uses Zener avalanche technology to generate truly random dice rolls, decisions, and random numbers. The display is a pair of three color 8x8 LED arrays. Self-diagnostics insure that the random number generator is working reliably.

There are seven modes to choose from, click on a thumbnail for a bigger picture:

Double 6-sided Dice
Double 20-sided Dice
Double Heads/Tails Coin Flip
Double Yes/No Decision Maker
Decimal Random Number Generator
Hex Random Number Generator
Random 3-color Stars

Press the POWER/MODE button to power on and select the desired random generator mode.
Hold the POWER/MODE button for 2 seconds to power off.
Press a ROLL button to generate a random result.
The device will automatically power off after 5 minutes of inactivity.

Operating Modes
The POWER/MODE button cycles through the operating modes, plus the diagnostic modes if they are enabled (see below).

Mode #1 - 6 Sided DiceTwo independent 6 sided dice.
Mode #2 - Heads/Tails Coin FlipTwo independent coins. 'H' for Heads, 'T' for Tails.
Mode #3 - Yes/No Decision MakerTwo independent decisions. 'Y' for Yes, 'N' for No.
Mode #4 - 20 Sided DiceTwo independent 20 sided dice.
Mode #5 - Decimal Random NumberTwo independent random number generators, 0 to 99.
Mode #6 - Hex Random NumberTwo independent random number generators, 0x00 to 0xFF (0 to 255).
Mode #7 - Random Stars DisplayContinuous display of pixels chosen by the random number generator.

Error Codes
The self-monitoring checks the random number generator hardware parameters to make sure that it's operating reliably. If it's not operating within specifications then an error code will be displayed when a ROLL button is pressed.

E1Boost voltage out of range
E2RNG signal rate not rational
E3Probability space reduction failed (indicates bad RNG source)

Diagnostic Modes
To enable the additional diagnostic modes hold down the left ROLL button while powering on.

Diagnostic #1Displays the boost voltage, which should be between 19 and 21 volts
Diagnostic #2Displays RNG min and max events/ms, should be between 10 and 200
Diagnostic #3Statistical analysis results for maximum run length of 0's and 1's
Diagnostic #4Statistical analysis results for 0/1 bias test

Design Documents

Schematic Diagramschematic_j720_zen_dice_2.pdf
3D Print Filesmechanical_j720_zen_dice_2.zip
PCB Gerbersgerbers_j720_zen_dice_2.zip
Source Code (Arduino)code_j720_zen_dice_2.zip
Source Code (PHP)php_j720_zen_dice_2.zip


Power Requirement5V Micro USB Charger
Dimensions103x103x26 mm (4x4x1 in.)


Available fully assembled and tested
Buy it at Tindie