Added example

Author: Henrik Snöman

examples/blinky_random.rs

@@ -0,0 +1,77 @@
+// Note: Code taken from stm32h7xx-hal
+//! This example toggles the Pin PA5 with a randomly generated period between 0
+//! and 200 milliseconds. The random period is generated by the internal
+//! hardware random number generator.
+
+#![deny(warnings)]
+#![no_main]
+#![no_std]
+
+use cortex_m_rt::entry;
+use embedded_hal::delay::DelayNs;
+use stm32h5xx_hal::{
+    delay::Delay,
+    pac,
+    prelude::*,
+    rng::{RngCore, RngExt},
+};
+#[macro_use]
+mod utilities;
+
+use log::info;
+
+#[entry]
+fn main() -> ! {
+    utilities::logger::init();
+    let cp = cortex_m::Peripherals::take().unwrap();
+    let dp = pac::Peripherals::take().expect("cannot take peripherals");
+
+    // Constrain and Freeze power
+    info!("Setup PWR...                  ");
+    let pwr = dp.PWR.constrain();
+    let pwrcfg = pwr.vos0().freeze();
+
+    // Constrain and Freeze clock
+    info!("Setup RCC...                  ");
+    let rcc = dp.RCC.constrain();
+    //let ccdr = rcc.sys_ck(100.MHz()).freeze(pwrcfg, &dp.SYSCFG);
+    let ccdr = rcc.sys_ck(100.MHz()).freeze(pwrcfg, &dp.SBS);
+
+    info!("");
+    info!("stm32h5xx-hal example - Random Blinky");
+    info!("");
+
+    let gpioa = dp.GPIOA.split(ccdr.peripheral.GPIOA);
+
+    // Configure PA5 as output.
+    let mut led = gpioa.pa5.into_push_pull_output();
+
+    // Get the delay provider.
+    let mut delay = Delay::new(cp.SYST, &ccdr.clocks);
+
+    // Get true random number generator
+    let mut rng = dp.RNG.constrain(ccdr.peripheral.RNG, &ccdr.clocks);
+    let mut random_bytes = [0u16; 3];
+    match rng.fill(&mut random_bytes) {
+        Ok(()) => info!("random bytes: {:?}", random_bytes),
+        Err(err) => info!("RNG error: {:?}", err),
+    }
+
+    loop {
+        let random_element: Result<u32, _> = rng.gen();
+
+        match random_element {
+            Ok(random) => {
+                // NOTE: the result of the expression `random % 200`
+                // is biased. This bias is called "modulo-bias". It is
+                // acceptable here for simplicity, but may not be
+                // acceptable for your application.
+                let period = random % 200_u32;
+
+                led.toggle();
+                delay.delay_ms(period);
+            }
+            Err(err) => info!("RNG error: {:?}", err),
+        }
+    }
+}

src/rng.rs

@@ -62,7 +62,8 @@ impl RngExt for RNG {
         // See RM0433 Rev 6 Section 33.3.6
         assert!(rng_clk > hclk / 32, "RNG: Clock too slow");
 
-        self.cr().modify(|_, w| w.ced().clear_bit().rngen().set_bit());
+        self.cr()
+            .modify(|_, w| w.ced().clear_bit().rngen().set_bit());
 
         Rng { rb: self }
     }
@@ -259,4 +260,4 @@ impl rand_core::RngCore for Rng {
 
 #[cfg(feature = "rand")]
 #[cfg_attr(docsrs, doc(cfg(feature = "rand")))]
-impl rand_core::CryptoRng for Rng {}
+impl rand_core::CryptoRng for Rng {}