First Open Object(ID generator)

mctrivia

I just finished my first object that I put in the object exchange.

obex.parallax.com/objects/410/

It generates a unique and permanent ID number for each board you make. Any suggestions on things to make it better?

grasshopper

Nice. This will come in handy. Great idea

scotta

Hey,

Great idea. I have a question ?

Should this:

if Long[noparse][[/noparse]MemoryLocation]|Long[noparse][[/noparse]MemoryLocation+4]==0

really read like this:

if Long[noparse][[/noparse]MemoryLocation]|Long[noparse][[/noparse]MemoryLocation+3]==0

(swapped +4 for +3)

Scott

mctrivia

nope 4 is correct. what that does is checks to see if the first 2 longs are 0. if so then it generates an id number. I could check all 8 longs but it is stetistically unlikely 1 in 2^62 that the first 2 longs would be 0

scotta

very cool.

mctrivia

thanks.

grasshopper

I thought about this for a bit and think that this object can not work as you expect it to. If the number is random then there is a chance that the number will repeat because it is limited by the range of the number system i.e. 0 to 32 bits. If i had a dice that had 32bits /or sides in my example/ and I kept rolling the dice ill eventually get repeats.

Am i thinking correctly?

mctrivia

technically it is possible to get the same number but very unlikely. 32 bits will almost never repeat(i would bet on it for under 10,000,000) just to be safe I generate 256 bits(you could make 1 for every computer chip on earth and even randomly not get 2 the same.)

grasshopper

I like this object idea and agree that its a low percentage that numbers will repeat. I implemented this object and did not like the 256bit version only due to the long number that my co-workers would have to log in the log book ( even displaying it as HEX). This is when I modified it to 32 bits and it worked great as a (hex). This is when I thought that the number would repeat.

Hum, Maybe using some letters would decrease the size and yet still able to use the 256 version.

mctrivia

I return it as 8 longs so you can use the number you need without Modifying.

use x longs for you project.

d=2^(32*x-12)

gives only 0.02% chance of repeat. d is max devices you will build

mctrivia

if you want a denser coding scheme look up


php base 64

in google

grasshopper

Hum, Thanks - Ill check it out.