SWCU185G January 2018 – June 2024 CC1312PSIP , CC1312R , CC1352P , CC1352R , CC2642R , CC2642R-Q1 , CC2652P , CC2652PSIP , CC2652R , CC2652RB , CC2652RSIP , CC2662R-Q1
The TRNG core uses dual-shot noise generators that create unpredictable jittering output when asynchronously sampled by the system clock provided to the TRNG. The outputs from the shot noise generators feed a complex nonlinear combinatorial circuit (mixer) that produces the final TRNG output (see Figure 7-10).
The TRNG core consists of two parts:
The true entropy source is based upon a predetermined number of free-running oscillators (FROs). The accumulation of timing jitter, caused (for the largest part) by shot noise, creates uncertainty intervals for the output transitions of each FRO. Sampling within the uncertainly interval generates a small amount of entropy, which is accumulated in an LFSR. Entropy generation with multiple FROs in parallel allows the entropy accumulation to be done far more rapidly than is possible with one FRO.