Struct Trng

pub struct Trng<'d> {
    pub rng: Rng,
    /* private fields */
}

True Random Number Generator (TRNG) driver

The Trng struct represents a true random number generator that combines the randomness from the hardware RNG and an ADC. This struct provides methods to generate random numbers and fill buffers with random bytes. Due to pulling the entropy source from the ADC, it uses the associated registers, so to use TRNG we need to “occupy” the ADC peripheral.

let mut buf = [0u8; 16];

// ADC is not available from now
let mut trng = Trng::new(peripherals.RNG, &mut peripherals.ADC1);
trng.read(&mut buf);
let mut true_rand = trng.random();
let mut rng = trng.downgrade();
// ADC is available now
let analog_pin = peripherals.GPIO3;
let mut adc1_config = AdcConfig::new();
let mut adc1_pin = adc1_config.enable_pin(
    analog_pin,
    Attenuation::Attenuation11dB
);
let mut adc1 = Adc::<ADC1>::new(peripherals.ADC1, adc1_config);
let pin_value: u16 = nb::block!(adc1.read_oneshot(&mut adc1_pin)).unwrap();
rng.read(&mut buf);
true_rand = rng.random();
let pin_value: u16 = nb::block!(adc1.read_oneshot(&mut adc1_pin)).unwrap();

Fields

rng: Rng

The hardware random number generator instance.

Implementations

impl<'d> Trng<'d>

pub fn new( rng: impl Peripheral<P = RNG>, adc: impl Peripheral<P = ADC1> + 'd, ) -> Self

Creates a new True Random Number Generator (TRNG) instance.

Arguments

• rng - A peripheral instance implementing the RNG trait.
• adc - A mutable reference to an Adc instance.

Returns

Returns a new Trng instance.

pub fn random(&mut self) -> u32

Reads currently available u32 integer from TRNG

pub fn read(&mut self, buffer: &mut [u8])

Fills the provided buffer with random bytes.

pub fn downgrade(self) -> Rng

Downgrades the Trng instance to a Rng instance and releases the ADC1.

Trait Implementations

impl Drop for Trng<'_>

fn drop(&mut self)

Executes the destructor for this type.

impl RngCore for Trng<'_>

Implementing RngCore trait from rand_core for Trng structure

fn next_u32(&mut self) -> u32

Return the next random u32.

fn next_u64(&mut self) -> u64

Return the next random u64.

fn fill_bytes(&mut self, dest: &mut [u8])

Fill dest with random data.

fn try_fill_bytes(&mut self, dest: &mut [u8]) -> Result<(), Error>

Fill dest entirely with random data.

impl Read for Trng<'_>

fn read(&mut self, buffer: &mut [u8]) -> Result<(), Self::Error>

Fills the provided buffer with random bytes.

type Error = Infallible

Error type

impl CryptoRng for Trng<'_>

Implementing a CryptoRng marker trait that indicates that the generator is cryptographically secure.