Servo API

Servo API

The Servo class controls a standard servo motor (0–180°) attached to a PWM-capable Arduino pin.

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Servo()

servo = Servo()

Creates an un-attached servo. You must call attach(pin) before any movement commands.

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Servo.attach()

Servo.attach(pin: int) -> None

Bind the servo to a PWM-capable digital pin.

Parameter	Type	Description
pin	int	Digital pin number (e.g. 9).

Requires: A Board must have been created beforehand (it uses Board.get_active_board()).

Raises: RuntimeError if no Board exists.

Board("/dev/ttyUSB0")
servo = Servo()
servo.attach(9)

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Servo.detach()

Servo.detach() -> None

Release the pin. Clears pin, current_angle, and the internal servo reference. Call attach() again before further movement.

servo.detach()

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Servo.write()

Servo.write(angle: int | float) -> None

Immediately move the servo to the given angle.

Parameter	Type	Description
angle	int/float	Target angle. Clamped to 0–180 internally.

Raises:

• RuntimeError if not attached.
• ValueError if angle is not a number.

servo.write(90)    # centre
servo.write(0)     # minimum
servo.write(180)   # maximum
servo.write(200)   # silently clamped to 180

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Servo.read()

Servo.read() -> int

Return the last angle written via write(), move_smooth(), or sweep().

Raises:

• RuntimeError if not attached.
• RuntimeError if write() has never been called (angle is unknown).

servo.write(90)
print(servo.read())  # 90

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Servo.move_smooth()

Servo.move_smooth(
    target_angle: int | float,
    delay_ms: int = 15,
) -> None

Move to target_angle one degree at a time with a pause between steps. Produces a smooth, visible rotation.

Parameter	Type	Default	Description
target_angle	int/float	—	Destination angle (clamped 0–180).
delay_ms	int	15	Milliseconds between each 1° step.

Behaviour when current_angle is None: jumps directly to target (same as write()).

Behaviour when target_angle == current_angle: does nothing.

servo.attach(9)
servo.write(0)
servo.move_smooth(180, delay_ms=10)  # smooth 0→180

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Servo.sweep()

Servo.sweep(
    start: int | float = 0,
    end: int | float = 180,
    step: int = 1,
    delay_ms: int = 15,
) -> None

Sweep the servo from start to end, stepping by step degrees each delay_ms milliseconds.

Parameter	Type	Default	Description
start	int/float	0	Starting angle (clamped 0–180).
end	int/float	180	Ending angle (clamped 0–180).
step	int	1	Degrees per step (must be > 0).
delay_ms	int	15	Milliseconds between each step.

Raises: ValueError if step <= 0.

Works in both directions: start < end sweeps up, start > end sweeps down.

servo.sweep(0, 180, 1, 15)     # slow sweep up
servo.sweep(180, 0, 5, 5)      # fast sweep down

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Servo.pin

Servo.pin -> int | None

The pin the servo is attached to, or None if detached.

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Servo.current_angle

Servo.current_angle -> int | None

The last commanded angle, or None if write() has never been called. Updated by write(), move_smooth(), and sweep().