Adafruit, SMBus2, and the PCA

#!/usr/bin/python3

import time
import math
from smbus2 import SMBus

# ============================================================================
# Adafruit PCA9685 16-Channel PWM Servo Driver
# ============================================================================

bus = SMBus("/dev/i2c-2")

class PWM :

    i2c = None

  # Registers/etc.
    address              = 0x40
    __SUBADR1            = 0x02
    __SUBADR2            = 0x03
    __SUBADR3            = 0x04
    __MODE1              = 0x00
    __PRESCALE           = 0xFE
    __LED0_ON_L          = 0x06
    __LED0_ON_H          = 0x07
    __LED0_OFF_L         = 0x08
    __LED0_OFF_H         = 0x09
    __ALLLED_ON_L        = 0xFA
    __ALLLED_ON_H        = 0xFB
    __ALLLED_OFF_L       = 0xFC
    __ALLLED_OFF_H       = 0xFD

    def __init__(self, address):
        self = self
        self.address = address
        #if (self):
        print("Reseting PCA9685")
        bus.write_i2c_block_data(bus, 0x00, data)

    def setPWMFreq(self, freq):
    # Sets the PWM frequency
        prescaleval = 25000000.0    # 25MHz
        prescaleval /= 4096.0       # 12-bit
        prescaleval /= float(freq)
        prescaleval -= 1.0
        #if (self):
        print("Setting PWM frequency to %d Hz" % freq)
        print("Estimated pre-scale: %d" % prescaleval)
        prescale = math.floor(prescaleval + 0.5)
        #if (self):
        print("Final pre-scale: %d" % prescale)

        oldmode = self.read_i2c_block_data(self.__MODE1);
        newmode = (oldmode & 0x7F) | 0x10             # sleep
        self.i2c.write_i2c_block_data(self.__MODE1, newmode)        # go to sleep
        self.write_i2c_block_data(self.__PRESCALE, int(math.floor(prescale)))
        self.write_i2c_block_data(self.__MODE1, oldmode)
        time.sleep(0.005)
        self.write_i2c_block_data(self.__MODE1, oldmode | 0x80)

    def setPWM(self, channel, on, off):
        # Sets a single PWM channel
        self.write_i2c_block_data(self.__LED0_ON_L+4 * channel, on & 0xFF)
        self.write_i2c_block_data(self.__LED0_ON_H+4 * channel, on >> 8)
        self.write_i2c_block_data(self.__LED0_OFF_L+4 * channel, off & 0xFF)
        self.write_i2c_block_data(self.__LED0_OFF_H+4 * channel, off >> 8)