Random number generator (RNG) RM0090
770/1749 RM0090 Rev 18
24.4.3 RNG data register (RNG_DR)
Address offset: 0x08
Reset value: 0x0000 0000
The RNG_DR register is a read-only register that delivers a 32-bit random value when read.
After being read, this register delivers a new random value after a maximum time of 40
periods of the RNG_CLK clock. The software must check that the DRDY bit is set before
reading the RNDATA value.
Bit 2 SECS: Seed error current status
0: No faulty sequence has currently been detected. If the SEIS bit is set, this means that a
faulty sequence was detected and the situation has been recovered.
1: One of the following faulty sequences has been detected:
– More than 64 consecutive bits at the same value (0 or 1)
– More than 32 consecutive alternances of 0 and 1 (0101010101...01)
Bit 1 CECS: Clock error current status
0: The RNG_CLK clock has been correctly detected. If the CEIS bit is set, this means that a
clock error was detected and the situation has been recovered
1: The RNG_CLK was not correctly detected (f
RNG_CLK
< f
HCLK
/16).
Bit 0 DRDY: Data ready
0: The RNG_DR register is not yet valid, no random data is available
1: The RNG_DR register contains valid random data
Note: An interrupt is pending if IE = 1 in the RNG_CR register.
Once the RNG_DR register has been read, this bit returns to 0 until a new valid value is
computed.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
RNDATA
rrrrrrrrrrrrrrrr
1514131211109876543210
RNDATA
rrrrrrrrrrrrrrrr
Bits 31:0 RNDATA: Random data
32-bit random data.
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