"""Classes for supporting Servomotors."""
from abc import abstractmethod
from typing import Type, Union
from j5.components.component import Component, Interface
# A servo can be powered down by setting its position to None.
ServoPosition = Union[float, None]
[docs]class ServoInterface(Interface):
"""An interface containing the methods required to control a Servo."""
[docs] @abstractmethod
def get_servo_position(self, identifier: int) -> ServoPosition:
"""
Get the position of a servo.
:param identifier: Port of servo to check.
:returns: Position of servo.
"""
raise NotImplementedError # pragma: no cover
[docs] @abstractmethod
def set_servo_position(
self,
identifier: int,
position: ServoPosition,
) -> None:
"""
Set the position of a servo.
:param identifier: Port of servo to set position.
:param position: Position to set the servo to.
"""
raise NotImplementedError # pragma: no cover
[docs]class Servo(Component):
"""A standard servomotor."""
def __init__(self, identifier: int, backend: ServoInterface) -> None:
self._backend = backend
self._identifier = identifier
[docs] @staticmethod
def interface_class() -> Type[ServoInterface]:
"""
Get the interface class that is required to use this component.
:returns: interface class.
"""
return ServoInterface
@property
def identifier(self) -> int:
"""
An integer to identify the component on a board.
:returns: component identifier.
"""
return self._identifier
@property
def position(self) -> ServoPosition:
"""
Get the current position of the Servo.
:returns: current position of the Servo
"""
return self._backend.get_servo_position(self._identifier)
@position.setter
def position(self, new_position: ServoPosition) -> None:
"""
Set the position of the Servo.
:param new_position: new position for the servo.
:raises ValueError: invalid servo position
"""
if new_position is not None:
if not -1 <= new_position <= 1:
raise ValueError
self._backend.set_servo_position(self._identifier, new_position)