servolib.py

# Rui Santos & Sara Santos - Random Nerd Tutorials
# Complete project details at https://RandomNerdTutorials.com/raspberry-pi-pico-servo-motor-micropython/

from machine import Pin, PWM

class Servo:
    __servo_pwm_freq = 50
    __min_u16_duty = 1802
    __max_u16_duty = 7864
    min_angle = 0
    max_angle = 180
    current_angle = 0.001


    def __init__(self, pin):
        self.__initialise(pin)


    def update_settings(self, servo_pwm_freq, min_u16_duty, max_u16_duty, min_angle, max_angle, pin):
        self.__servo_pwm_freq = servo_pwm_freq
        self.__min_u16_duty = min_u16_duty
        self.__max_u16_duty = max_u16_duty
        self.min_angle = min_angle
        self.max_angle = max_angle
        self.__initialise(pin)


    def move(self, angle):
        # round to 2 decimal places, so we have a chance of reducing unwanted servo adjustments
        angle = round(angle, 2)
        # do we need to move?
        if angle == self.current_angle:
            return
        self.current_angle = angle
        # calculate the new duty cycle and move the motor
        duty_u16 = self.__angle_to_u16_duty(angle)
        self.__motor.duty_u16(duty_u16)
    
    def stop(self):
        self.__motor.deinit()
    
    def get_current_angle(self):
        return self.current_angle

    def __angle_to_u16_duty(self, angle):
        return int((angle - self.min_angle) * self.__angle_conversion_factor) + self.__min_u16_duty


    def __initialise(self, pin):
        self.current_angle = -0.001
        self.__angle_conversion_factor = (self.__max_u16_duty - self.__min_u16_duty) / (self.max_angle - self.min_angle)
        self.__motor = PWM(Pin(pin))
        self.__motor.freq(self.__servo_pwm_freq)