embedded-stepper

no_std stepper motor library for Rust, built on embedded-hal — and a port of the classic Arduino Stepper interface/behavior.

This crate provides a tiny, portable stepper motor controller for bare-metal targets. It reuses the familiar Arduino Stepper API concepts (steps per revolution, setSpeed, step) while embracing Rust’s generics and the [embedded-hal] traits for GPIO and timing.

Highlights

• Port of Arduino Stepper: same model and sequencing style, now in Rust.
• no_std: suitable for MCUs; no heap, no OS.
• embedded-hal 1.0 compatible:
  • Pin control via embedded_hal::digital::OutputPin
  • Timing via embedded_hal::delay::DelayNs
• Common wirings included: 2‑pin, 4‑pin, and 5‑pin coil drivers
• Driver trait: users can implement drivers for other types of motors
• Ergonomic builders & type aliases for shorter type signatures.

Quick Start

The following example works with the esp32-c3 development board:

#![no_std]
//Setup clock and peripherals
let config = esp_hal::Config::default().with_cpu_clock(CpuClock::default());
let peripherals = esp_hal::init(config);

//Get the 4 GPIO pins, change these values based on your wiring
let p1 = peripherals.GPIO0;
let p2 = peripherals.GPIO1;
let p3 = peripherals.GPIO2;
let p4 = peripherals.GPIO3;

//Setup the 4 pins as output, low, no pull and Push/Pull (default output config)
let op1 = Output::new(p1, Level::Low, OutputConfig::default());
let op2 = Output::new(p2, Level::Low, OutputConfig::default());
let op3 = Output::new(p3, Level::Low, OutputConfig::default());
let op4 = Output::new(p4, Level::Low, OutputConfig::default());

//Adjust these values to fit your stepper motor. See the Arduino stepper library for more info
let speed = 625;
let steps_per_rev = 48;

//Instantiate the motor with the 4 output pins
let mut motor = create_stepper_4pin(op1, op2, op3, op4, Delay::new(), steps_per_rev);

motor.set_speed(speed);

//Turn motor
let _ = motor.step(steps_per_rev as i32 * 10);

//Reverse motor
let _ = motor.step(steps_per_rev as i32 * -10);

//Deenergise coils after use
let _ = motor.deenergise();

Design Notes

• Arduino parity: The public API mirrors Arduino’s Stepper where it makes sense (e.g., set_speed, step, steps per revolution). Internally, the controller is generic and decoupled.
• Blocking by design: Stepper::step is blocking. For tight real-time loops, consider calling it from a cooperative scheduler or extend the crate with a non-blocking tick() style API.
• Wiring/Sequences: 2/4/5 pin drivers implement simple 4-state sequences. Adjust sequences if your hardware requires half-stepping or microstepping—this crate provides a foundation rather than heavy abstraction.

Current Limitations (and Roadmap)

• Error handling: The built-in drivers currently use type Error = () and ignore pin I/O errors (they let _ = pin.set_*()).
  Planned: bind each driver’s Error to the underlying pin error (type Error = <P1 as OutputPin>::Error) and propagate with ? for full embedded-hal compliance.
• Non-blocking control: Provide an optional non-blocking controller (tick()), plus acceleration/deceleration profiles.

Installing

Add to your Cargo.toml:

[dependencies]
embedded-stepper = { git = "https://github.com/ray33ee/embedded-stepper", default-features = false }
embedded-hal = { version = "1.0", default-features = false }

This crate is no_std by default; keep default-features = false.

License

MIT © 2025 — see LICENSE.

Acknowledgements

This work intentionally ports the behavior and ergonomics of the Arduino Stepper library to Rust, while integrating with the embedded-hal ecosystem.