Collaborate Disseminate
If you want to start an argument at a Hackaday meeting, you have only to ask something like “How much does this weigh?” or “What time is it?” But if …read more Continue reading Linear Feedback Shift Registers for FPGAs
A truly random number is something that is surprisingly difficult to generate. A typical approach is to generate the required element of chance from a natural and unpredictable source, such as radioactive decay or thermal noise. By contrast it is extremely easy to generate numbers that look random but in …read more
Continue reading The Simplest Of Pseudo Random Number Generators
…theoretically, anyway. When [Quinn] lucked into a bunch of 5 mm red LEDs and a tube of 74LS164 shift registers, a project sprang to mind: “The Forever Number,” a pseudo-random number generator with a period longer than the age of the universe. Of course, the components used will fail long before the sequence repeats, but who cares, this thing looks awesome!
The core of the project is a 242-bit linear-feedback shift register (LFSR) constructed from (31) 74LS164’s. An XOR gate and inverter computes the next bit of the sequence by XNOR’ing two feedback bits taken from taps on the register, …read more
What do you do, when you need a random number in your programming? The chances are that you reach for your environment’s function to do the job, usually something like rand() or similar. This returns the required number, and you go happily on your way.
Except of course the reality isn’t quite that simple, and as many of you will know it all comes down to the level of randomness that you require. The simplest way to generate a random number in software is through a pseudo-random number generator, or PRNG. If you prefer to think in hardware terms, the …read more
Continue reading Entropy and The Arduino: When Clock Jitter is Useful
When [::vtol::] wants to generate random numbers he doesn’t simply type rand() into his Arduino IDE, no, he builds a piece of art. It all starts with a knob, presumably connected to a potentiometer, which sets a frequency. An Arduino UNO takes the reading and generates a tone for an upward-facing speaker. A tiny ball bounces on that speaker where it occasionally collides with a piezoelectric element. The intervals between collisions become our sufficiently random number.
The generated number travels up the Rube Goldberg-esque machine to an LCD mounted at the top where a word, corresponding to our generated number, …read more
