examples: Add random example

examples/laze.yml

@@ -13,4 +13,5 @@ subdirs:
   - embassy-usb-keyboard
   - hello-world
   - minimal
+  - random
   - threading

examples/random/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "random"
+version = "0.1.0"
+authors.workspace = true
+edition.workspace = true
+publish = false
+
+[dependencies]
+# not enabling riot-rs/hwrng even though it's currently needed -- laze takes
+# care of that.
+riot-rs = { path = "../../src/riot-rs", features = ["threading"] }
+riot-rs-boards = { path = "../../src/riot-rs-boards" }
+
+riot-rs-random = { version = "0.1.0", path = "../../src/riot-rs-random" }
+rand = { version = "0.8.5", default-features = false }

examples/random/README.md

@@ -0,0 +1,17 @@
+# random
+
+## About
+
+This application performs a very important role in physical computing:
+It produces randomness in the form of a dice roll (values 1 to 6, inclusive).
+It prints out a single random value via the debug console.
+
+## How to run
+
+In this folder, run
+
+    laze build -b nrf52840dk run
+
+This will print different values most of the time on all boards it can be built
+on. If there is no way to get startup entropy on a board, the example can not
+be built.

examples/random/laze.yml

@@ -0,0 +1,5 @@
+apps:
+  - name: random
+    selects:
+      - ?release
+      - rng

examples/random/src/main.rs

@@ -0,0 +1,19 @@
+#![no_main]
+#![no_std]
+#![feature(type_alias_impl_trait)]
+#![feature(used_with_arg)]
+
+use riot_rs::debug::{println};
+
+#[riot_rs::thread(autostart)]
+fn main() {
+    use rand::Rng as _;
+    let mut rng = riot_rs_random::get_rng();
+
+    let value = rng.gen_range(1..=6);
+
+    println!(
+        "The random value of this round is {}.",
+        value
+    );
+}