True Random Number Generator for a True Hacker (2015)

Of course, it is easy to create a very long pseudorandom sequence in software, but even the best PRNG (Pseudorandom Number Generator) needs a good random seed, as we don’t want to get the same sequence each time we switch on the unit, do we? So, if you need a few random bytes (for PRNG seed or some magic number), you can use uninitialized RAM contents to generate them. For instance, if your MCU contains 4K of RAM (like PIC18F2525, if you include SFR area), and you need a 32-bit seed, you can split RAM into four 1024-byte blocks and use them to generate four random bytes.

Source: hackaday.com