AT90SCR100 datasheet(335/433 Pages) ATMEL

335 / 433 page

335

TPR0327AY–SMS–30Jan09

AT90SCR100

24. Random Number Generator

24.1

Features

• Automatic generation of 8-bits Random Number

• Private Oscillator source used for unpredictable random generation

24.2

RNG Definition

The Random Number Generator of the AT90SCR100 uses a specific oscillator source controlled

by the RNGCR.ROSCE bit.

This oscillator adapt is used to activate a hardware process.

This hardware process can be seeded through the LFSR3 to LFSR0 registers.

The result of the hardware post-processing can be read from the RDWDR register.

LFSR3 to LFSR0 registers must be changed while the oscillator source is stopped

(RNGCR.ROSCE bit is cleared).

When RNGCR.ROSCE bit is cleared, the oscillator source is stopped (as well as the shift regis-

ter and the hardware post processing).

When RNGCR.ROSCE bit is set, the oscillator is activated and the configuration of the shift reg-

ister and of the hardware post-processing depends on the LFSR registers and previous

hardware iterations.

After chip start-up, some oscillator cycles will be performed in order to initialise to a

different random value after each chip power-up.

Oscillator

Hardware

Postprocessing

LFSR0

LFSR3

RDWDR

Note

AT90SCR100 데이터시트(PDF) 335 Page - ATMEL Corporation