I Ching Machine

Introduction

In "The Long Dark Tea Time of the Soul" (by Douglas Adams) the main character, Dirk Gently, consults an I Ching oracle in a little electronic box.

There a numerous versions in software of the I Ching for PCs, but due to the fact that true "randomness" is better done in hardware, an I Ching "machine" would be more authentic on an MCU combined with a random generator.

Also, some people have difficulty figuring if its a "moving" or "fixed" line after casting the coins; a bit of hardware logic can solve this and display the oracleŽs answers for them.

This project is to basically take the code and hardware here for the rngbox:

http://www.cryogenius.com/hardware/rng/

and turn it into an I Ching machine.

Logic

A first "throw" of the three coins is, in logic terms, two random binary bits (or a total 4 possibilities):

0 0
0 1
1 0
1 1

The first bit (1 or 0) can be represented as
"Yin" -- -- or "Yang" -----

The second bit (1 or 0) would represent if this first line was "moving" or "not moving".

So this gives the possible four states which are popularly generated by throwing three coins together:

http://en.wikipedia.org/wiki/I_Ching_divin...ree-coin_method


"Looped" 6 six times this would create the first hexagram. Ideally youŽd want the random bits to get cast at excactly the same time, but given that the Tao can probably sort that out, two sequential random bits would do as a first "pair".

Interestingly, to then get the resultant second hexagram simply XOR the two bits:

So a Yin -- -- (say 1) XOR a non moving bit (0) gives "1". So Yin (non moving) stays as Yin.

If a Yin is with a moving bit (1 XOR 1) you get "0" or "Yang" and so on.

The other ports being used for output to LEDŽs / dot matrix display and a push button for "casting"


Implementation:

Each 2 bit pairs are sequentially read into a GPIO port.
The first bit is stored in (lets say) the LSB of register A
The second bit stored somewhere else, LSB register B
The third bit is stored in A, but the next location in the register row of A (call it A2).

This is looped six times so that you end up with 6 bits in A and (as close as you can get to the random bits being in pairs) and 6 bits in B which overlap each other. The LSB of A pairs with LSB of B and so on. When the two register contents are later XORed you end up with
the final hexagram in the result register C.

This looks like:

A: * * X X X X X -X(first bit read in)

B: * * X X X X X -X(second bit read in - i.e. the first bit which was just read into "A" now has its parallel corresponding "moving or not" bit in B, together constituting the first throw)

A * * X X X X X- X(third bit read in) and so on

A XOR B store result in C = second hexagram.

Only first 6 bits (of 8 bit register) are used.


Output:

Simplest would be six L.E.D. s lighting up in a vertical line to represent hexagram 1 - this is essentially the output of register A and the LEDŽs could be rectangle.

The next six LEDŽs next to those could be round points representing if each corresponding line was correspondingly "moving" or not (register B output)

The last would be register C output for the second hexagram, could be displayed on more LEDs but cheaper and less power hungry to simply use existing display.


Timing:

Cool would be to have the hexagrams being generated all the time as the "Tao flows" - you hit a button to cast a momentary reading, then LEDs stop flickering and display first one hexagram then the other when you hit again.


Look up table:

You could further represent the possible 64 hexagrams (generated from the above) as 64 pre stored binary numbers. These then link to 64 "real" BCD numbers, but its not a simple BCD conversion: For example the binary output for register A could be 111111 which would be all yin lines, representing the actual hexagram number "2".

For the matrix see: http://en.wikipedia.org/wiki/I_Ching

The 64 code array could sit in memory as a look up table, for the LED digits (under the LED lines) which light up when a reading is made.

So you hit a button, the oracle shows six lines (as six LEDs) from bottom to top - then the corresponding "moving LED" would light next to any of the lines which are "moving". Underneath there is a two digit LED display showing which hexagram was cast. When the button is pushed again it XORs the lines with the moving ones (if any) and the number changes too.

Or use a dot matrix display using a Max driver like the MAX6952 (see Maxim app. note 1033) for both lines and numbers?


Any comments / suggestions please let me know. I am new at programming but can build hardware ok - if anyone wanted to have a go with me on this IŽd be happy to do a prototype in SMD format eventually.

Further refereneces to randomness:

http://www.robertnz.net/hwrng.htm
http://willware.net:8080/hw-rng.html
http://en.wikipedia.org/wiki/Hardware_rand...umber_generator

greetz
bazthewaz@gmx.de