write example for new device system

Author: Uxugin

examples/devices.rs

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright 2024-2025 UxuginPython
+use rrtk::devices::provided::Differential;
+use rrtk::devices::*;
+use rrtk::*;
+#[cfg(not(feature = "devices"))]
+compile_error!("Enable the `devices` feature to run this example.");
+///Format [`AngularState`] like a row vector for ease of reading.
+fn format_state(state: AngularState) -> String {
+    format!(
+        "[ {} {} {} ]",
+        state.position.into_inner(),
+        state.velocity.into_inner(),
+        state.acceleration.into_inner()
+    )
+}
+fn main() {
+    let mut system = System::<6>::new();
+    let diff_left = system.new_node().unwrap();
+    let diff_right = system.new_node().unwrap();
+    let diff_top = system.new_node().unwrap();
+    let enc_left = system.new_node().unwrap();
+    let enc_right = system.new_node().unwrap();
+    let demo_top = system.new_node().unwrap();
+    system.connect(diff_left, enc_left);
+    system.connect(diff_right, enc_right);
+    system.connect(diff_top, demo_top);
+    //The provided Differential device adds the states of its left and right nodes.
+    let mut differential = Differential::new(diff_left, diff_right, diff_top);
+    //Fake encoders by directly setting the states.
+    system.set_state_local(
+        enc_left,
+        Some(AngularState::new(
+            Dimensionless::new(1.0),
+            InverseSecond::new(2.0),
+            InverseSecondSquared::new(3.0),
+        )),
+    );
+    system.set_state_local(
+        enc_right,
+        Some(AngularState::new(
+            Dimensionless::new(4.0),
+            InverseSecond::new(5.0),
+            InverseSecondSquared::new(6.0),
+        )),
+    );
+    //There's only one device in this example, and it's not actually a continuously updating
+    //system, so we only update once. However, when you actually use the device system, you should
+    //call device_update for all your devices in a loop. The order of the devices in this loop
+    //shouldn't usually matter significantly, but you may want to experiment with it if you need
+    //the utmost updating speed.
+    differential.device_update(&mut system);
+    //We directly set the encoder states, so we use get_state_local to access them.
+    let enc_left_state = system.get_state_local(enc_left).unwrap();
+    let enc_right_state = system.get_state_local(enc_right).unwrap();
+    //demo_top is connected to diff_top, and diff_top is providing the state, so we use
+    //get_state_connected. This is one of a few cases where get_state_true would also be fine to
+    //use.
+    let demo_state = system.get_state_connected(demo_top).unwrap();
+    println!(
+        "{} + {} = {}",
+        format_state(enc_left_state),
+        format_state(enc_right_state),
+        format_state(demo_state)
+    );
+}