[esp] Add Rust example with std.

esp/rust/01_esp-idf-std/src/main.rs

@@ -0,0 +1,35 @@
+use esp_idf_hal::delay::FreeRtos;
+use esp_idf_hal::ledc::*;
+use esp_idf_hal::peripherals::Peripherals;
+use esp_idf_hal::prelude::*;
+
+fn main() -> anyhow::Result<()> {
+    esp_idf_hal::sys::link_patches();
+
+    println!("Configuring output channel");
+
+    let peripherals = Peripherals::take()?;
+    // Channel for on-board LED on ESP32
+    let mut channel = LedcDriver::new(
+        peripherals.ledc.channel0,
+        LedcTimerDriver::new(
+            peripherals.ledc.timer0,
+            &config::TimerConfig::new().frequency(25_u32.kHz().into()),
+        )?,
+        peripherals.pins.gpio2,
+    )?;
+
+    println!("Starting duty-cycle loop");
+    let max_duty = channel.get_max_duty();
+    // Cycle the channel duty every 2s to visually show that things are working when flashed.
+    for numerator in [0, 1, 2, 3, 4, 5].iter().cycle() {
+        println!("Duty {numerator}/5");
+        channel.set_duty(max_duty * numerator / 5)?;
+        FreeRtos::delay_ms(2000);
+    }
+
+    // We want this to run forever, so don't let the application terminate.
+    loop {
+        FreeRtos::delay_ms(1000);
+    }
+}