NXP Semiconductors K32 L2A Series, Reference Manual, Page: 1213 / 1379

48.1.3 SA-TRNG hardware functional description.
SA-TRNG functionality consists of several major subcomponents. This table describes
these subcomponents.
Table 48-1. SA-TRNG subcomponents.
Description Cross-reference(s)
Interfaces
Register interface
• Used for access to configuration, control, status and
debugging registers
Register interface (IP Slave bus)
True Random Number Generator (TRNG) Standalone True Random Number Generator (SA-TRNG).
48.1.3.1 Software Use Cases for the Stand Alone TRNG.
There are four things that a user (programmer/integrator) will want to do with a TRNG.
• Initialization.
Set up the parameters to proper values, and start generation of the first block of
entropy. This is done once.
• Read entropy from the TRNG, and start generation of the next block of entropy.
This is done many times and is the normal flow of operation.
• Run a self-test on the TRNG, to assure proper continued operation.
This involves taking TRNG off-line, setting some self-test parameters, running
TRNG, and then reading the statistical test registers, to see that they are within
proper operation values. This may not be needed, as TRNG has built-in self-test.
• Off-line determination and checking of TRNG parameter values.
This is done in development in order to determine the proper initialization and self-
test parameters. The TRNG is taken off-line. Test parameter values are written and
entropy generation is started. If the statistical tests indicate poor operation (i.e.,
failing statistical tests), the entropy_delay value should be increased and entropy
generation should be re-started. Every case is a variation of setting TRNG parameter
values, starting or re-starting entropy generation and reading out the entropy. This
process requires pausing or stopping and re-starting the TRNG.
Chapter 48 SA-TRNG Standalone
K32 L2A Reference Manual, Rev. 2, 01/2020
NXP Semiconductors 1213