ST STM32L4+ Series Reference Manual page 1073

RM0432 True random number generator (RNG) applied to STM32L4Rxxx and STM32L4Sxxx only
32.6 RNG entropy source validation
32.6.1 Introduction
In order to assess the amount of entropy available from the RNG, STMicroelectronics has
tested the peripheral using German BSI AIS-31 statistical tests (T0 to T8). The results can
be provided on demand or the customer can reproduce the tests.
32.6.2 Validation conditions
STMicroelectronics has tested the RNG true random number generator in the following
conditions:
•
RNG clock rng_clk= 48 MHz (CED bit = '0' in RNG_CR register) and rng_clk = 400 kHz
(CED bit = '1' in RNG_CR register).
RNG
NISTC RNG_CONFIG1
Config
bit
A 0
B 1
1. When writing this register magic number 0x17590ABC must be written immediately before the indicated value
32.6.3 Data collection
In order to run statistical tests it is required to collect samples from the entropy source at raw
data level as well as at the output of the entropy source.
Contact STMicroelectronics if above samples need to be retrieved for your product.
Table 219. RNG configurations
RNG_CR bits
CLKDIV RNG_CONFIG2
[5:0] [3:0]
0x0F 0x0
0x18 0x0
RNG_CONFIG3
[2:0] [3:0]
0x0 0xD
0x0
RM0432 Rev 6
Nb
loop
CED
(N)
bit
0 2
0x0 0 2
RNG_HTCR
(1)
register
0x0000
A2B3
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