The Autocorrelation test determine if there over time is a bias in the random bit sequences towards certain values or patterns, or if the bits in the sequence are truly independent.
If a bias in the collected bit stream is detected, the output will be discarded
and the error flagged in register AUTOCORR_STATISTIC.
If a bias is detected four consecutive times in a row, the autocorrelation test
will trigger event AUTOCORR_ERR_INT in register
RNG_ISR. In this situation the TRNG will cease to
function until manually reset using register RNG_SW_RESET.