OpenMV

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main.py:

from pyb import I2C
import time
from servoctrl import ServoCtrl


i2c = I2C(2, I2C.MASTER) # The i2c bus must always be 2.

servos = ServoCtrl(i2c)

servos.position(0,90)
time.sleep(1000)
servos.position(0,0)
time.sleep(1000)
servos.position(0,90)
time.sleep(1000)
servos.position(0,0)

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import ustruct
import time


class PCA9685:
    def __init__(self, i2c, address=0x40):
        self.i2c = i2c
        self.address = address
        self.reset()

    def _write(self, address, value):
        self.i2c.mem_write(bytearray([value]), self.address, address )

    def _read(self, address):
        return self.i2c.mem_read(1, self.address, address)[0]

    def reset(self):
        self._write(0x00, 0x00) # Mode1

    def freq(self, freq=None):
        if freq is None:
            return int(25000000.0 / 4096 / (self._read(0xfe) - 0.5))
        prescale = int(25000000.0 / 4096.0 / freq + 0.5)
        old_mode = self._read(0x00) # Mode 1
        self._write(0x00, (old_mode & 0x7F) | 0x10) # Mode 1, sleep
        self._write(0xfe, prescale) # Prescale
        self._write(0x00, old_mode) # Mode 1
        time.sleep(1)
        self._write(0x00, old_mode | 0xa1) # Mode 1, autoincrement on

    def pwm(self, index, on=None, off=None):
        if on is None or off is None:
            data = self.i2c.mem_read(self.address, 0x06 + 4 * index, 4)
            return ustruct.unpack('<HH', data)
        data = ustruct.pack('<HH', on, off)
        self.i2c.mem_write(data, self.address, 0x06 + 4 * index)

    def duty(self, index, value=None, invert=False):
        if value is None:
            pwm = self.pwm(index)
            if pwm == (0, 4096):
                value = 0
            elif pwm == (4096, 0):
                value = 4095
            value = pwm[1]
            if invert:
                value = 4095 - value
            return
        if not 0 <= value <= 4095:
            return ValueError("Out of range")
        if invert:
            value = 4095 - value
        if value == 0:
            self.pwm(index, 0, 4096)
        elif value == 4095:
            self.pwm(index, 4096, 0)
        else:
            self.pwm(index, 0, value)

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from pca9685 import PCA9685
import math


class ServoCtrl( PCA9685 ):
    """ Servo Controleur - Allow you to control the servo 0 to 15 on the PCA9685 PWM Driver """
    def __init__(self, i2c, address=0x80, freq=50, min_us=600, max_us=2400,
                 degrees=180):
        PCA9685.__init__( self, i2c=i2c, address=address)

        self.period = 1000000 / freq
        self.min_duty = self._us2duty(min_us)
        self.max_duty = self._us2duty(max_us)
        self.degrees = degrees

        # Init the freq on PCA9685
        self.freq(freq)

    def _us2duty(self, value):
        return int(4095 * value / self.period)

    def position(self, index, degrees=None, radians=None, us=None, duty=None):
        span = self.max_duty - self.min_duty
        if degrees is not None:
            duty = self.min_duty + span * degrees / self.degrees
        elif radians is not None:
            duty = self.min_duty + span * radians / math.radians(self.degrees)
        elif us is not None:
            duty = self._us2duty(us)
        elif duty is not None:
            pass
        else:
            return self.duty(index)
        duty = min(self.max_duty, max(self.min_duty, int(duty)))
        self.duty(index, duty)

    def release(self, index):
        self.duty(index, 0)

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