65536 samples watchdog xorshifted plot
Only 68 bits per second because the minimum watchdog timer is 16 ms and contributes one bit per interrupt, but it requires no external components and seems to be more truly random than TrueRandom:
Entropy = 7.996943 bits per byte.
Optimum compression would reduce the size
of this 65536 byte file by 0 percent.
Chi square distribution for 65536 samples is 277.59, and randomly
would exceed this value 15.83 percent of the times.
Arithmetic mean value of data bytes is 127.8158 (127.5 = random).
Monte Carlo value for Pi is 3.126899835 (error 0.47 percent).
Serial correlation coefficient is -0.007752 (totally uncorrelated = 0.0).