Module servo 

A device abstraction for hobby servos on ESP LEDC PWM.

This module provides both direct servo control (servo!) and servo animationl (servo_player!).

Use servo! for a keyword-driven typed constructor.

After reading the examples below, see also:

• servo! — Direct servo control without animation support.
• servo_player! — Macro to generate a servo player struct type (includes syntax details). See ServoPlayerGenerated for a sample of a generated type.
• combine! & linear — Macro and function for creating complex motion sequences.
• Servo — Trait defining core methods and constants for direct servo control.
• ServoPlayer — Trait defining core methods and constants for animatable servos.

How Servos Work

When you call set_degrees(45), the microcontroller starts sending a LEDC control signal to the servo, telling it to move to and hold at 45 degrees. The hardware generates this control signal automatically in the background, taking no CPU time. The control signal remains active until you change it or call relax().

The servo itself has no idea what angle it is currently at. It simply moves as fast as it can to match whatever angle the current control signal specifies. The library does not, and cannot, wait for the servo to reach a position. This is why you must wait (for example, using Timer::after()) after calling set_degrees() to give the servo time to physically reach the target position.

This device abstraction, servo_player, adds a background software task around the hardware control signal.

Controlling Multiple Servos

Supports multiple servos, where each servo consumes one LEDC timer resource and one LEDC channel resource. The macro-generated link-time ownership claims enforce this exclusivity so duplicate timer/channel selections fail at link time.

Example: Basic Servo Control

This example demonstrates basic servo control: moving to a position, relaxing, and using animation. Here, the generated struct type is named Servo11.

use device_envoy_esp::{Result, init_and_start, servo::{Servo as _, servo}};
use embassy_time::{Duration, Timer};

servo! {
    Servo11 {
        pin: GPIO11,
        timer: Timer0,
        channel: Channel0,
    }
}

async fn inner_main() -> Result<Infallible> {
    init_and_start!(p, ledc: ledc);
    let servo11 = Servo11::new(&ledc, p.GPIO11)?;
    servo11.set_degrees(45);
    Timer::after(Duration::from_secs(1)).await;
    servo11.relax();
    core::future::pending().await
}

Example: Multi-Step Animation

This example combines 40 animation steps using linear and combine! to sweep up, hold, sweep down, hold pattern. Here, the generated struct type is named ServoSweep.

use device_envoy_esp::{Result, init_and_start, servo::{AtEnd, Servo as _, ServoPlayer as _, combine, linear, servo_player}};
use embassy_time::Duration;

servo_player! {
    ServoSweep {
        pin: GPIO12,
        timer: Timer1,
        channel: Channel1,
        max_steps: 40,
    }
}

async fn inner_main(spawner: embassy_executor::Spawner) -> Result<Infallible> {
    init_and_start!(p, ledc: ledc);
    let servo_sweep = ServoSweep::new(&ledc, p.GPIO12, spawner)?;
    const STEPS: [(u16, Duration); 40] = combine!(
        linear::<19>(0, 180, Duration::from_secs(2)),
        [(180, Duration::from_millis(400))],
        linear::<19>(180, 0, Duration::from_secs(2)),
        [(0, Duration::from_millis(400))]
    );
    servo_sweep.animate(STEPS, AtEnd::Loop);
    core::future::pending().await
}

Modules

servo_player_generated

Sample generated servo-player type documentation.

Macros

combine

Combine multiple animation step arrays into one larger array.

servo

Macro to generate a direct-servo struct type (includes syntax details).

servo_player

Macro to generate a servo player struct type (includes syntax details).

Structs

ServoStatic

LEDC-backed servo static resources and motion configuration.

Enums

AtEnd

Animation end behavior.

Constants

SERVO_MAX_US_DEFAULT

Default maximum pulse width for hobby servos (microseconds).

SERVO_MIN_US_DEFAULT

Default minimum pulse width for hobby servos (microseconds).

Traits

Servo

Platform-agnostic servo device contract.

ServoPlayer

Platform-agnostic servo-player device contract.

Functions

combine

Combine two animation step arrays into one larger array.

linear

Build a const linear sequence of animation steps as an array.