Ultrasonic Sensor HC-SR04 Example

examples/ultrasonic_sensor_hcsr04.rs

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+use esp_idf_hal::delay::FreeRtos;
+use esp_idf_hal::gpio::*;
+use esp_idf_hal::peripherals::Peripherals;
+use log::*;
+use esp_idf_svc::systime::EspSystemTime;
+
+fn main() {
+    // Initialize logging and necessary peripherals
+    esp_idf_sys::link_patches();
+    esp_idf_svc::log::EspLogger::initialize_default();
+    info!("Hello, world!");
+
+    let peripherals = Peripherals::take().unwrap();
+
+    // Configure pins for trigger and echo
+    let mut trigger_pin = PinDriver::output(peripherals.pins.gpio4).expect("Error configuring trigger pin");
+    let echo_pin = PinDriver::input(peripherals.pins.gpio5).expect("Error configuring echo pin");
+
+
+    loop {
+        // Send a 10us pulse to the trigger pin to start the measurement
+        trigger_pin.set_high().expect("Error: Unable to set trigger pin high");
+        FreeRtos::delay_us(10);
+        trigger_pin.set_low().expect("Error: Unable to set trigger pin low");
+
+        // Wait for the echo pin to go high (start of pulse)
+        while !echo_pin.is_high() {}
+
+        // Measure the duration of the echo pulse (in microseconds)
+        let start_time = EspSystemTime {}.now().as_micros();
+        while echo_pin.is_high() {}
+        let end_time = EspSystemTime {}.now().as_micros();
+
+        // Calculate the duration of the echo pulse in microseconds
+        let pulse_duration = end_time - start_time;
+
+        // Calculate the distance based on the speed of sound (approximately 343 m/s)
+        // Distance in centimeters: duration * speed_of_sound / 2 (since the signal goes to the object and back)
+        let distance_cm = (pulse_duration as f32 * 0.0343) / 2.0;
+
+        // Distance in inches: distance_cm / 2.54 (since 1 inch = 2.54 cm)
+        let distance_inches = distance_cm / 2.54;
+
+        // Print the measured distance in both centimeters and inches
+        info!("Distance: {:.2} cm, {:.2} inches", distance_cm, distance_inches);
+
+        // Wait for a brief moment before taking the next measurement
+        FreeRtos::delay_ms(1000);
+    }
+
+}