u5 - add working rng example

examples/stm32u5/src/bin/rng.rs

@@ -0,0 +1,25 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::rng::Rng;
+use embassy_stm32::{bind_interrupts, peripherals, rng};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    RNG => rng::InterruptHandler<peripherals::RNG>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+
+    info!("Hello World!");
+
+    let mut rng = Rng::new(p.RNG, Irqs);
+
+    let mut buf = [0u8; 16];
+    unwrap!(rng.async_fill_bytes(&mut buf).await);
+    info!("random bytes: {:02x}", buf);
+}