esp32_th02.py

from time import sleep

class TH02:
  """Interface to the TH02 temp/humidity sensor."""
  CHECK_DELAY = 0.025

  CONVERSION_TEMP = 0x11
  # Convert without the built-in heater
  CONVERSION_HUMIDITY = 0x01

  REGISTER_STATUS = 0x00
  REGISTER_DATAH = 0x01
  REGISTER_DATAL = 0x02
  REGISTER_CONFIG = 0x03

  ADDRESS = 0x40

  def __init__(self, i2c):
    self.i2c = i2c

  def init_temp(self):
    """Send command to TH02 for convert temperature"""

  def init_humidity(self):
    """Send command to TH02 for convert humidity"""
    self.i2c.write_register(self.ADDRESS, self.REGISTER_CONFIG, self.CONVERSION_HUMIDITY)

  def is_ready(self):
    """Is sensor done with conversion"""
    status = self.i2c.read_register(self.ADDRESS, self.REGISTER_STATUS)
    # Extract ready bit
    ready = not (status & 0x01)
    return bool(ready)

  def wait_until_ready(self):
    "Wait until conversion completes"
    sleep(self.CHECK_DELAY)
    for _ in range(8):
      if self.is_ready():
        return True
      sleep(self.CHECK_DELAY)
    return False

  def read_data(self):
    """Read the DATA registers"""
    data = self.i2c.read_register(self.ADDRESS, self.REGISTER_DATAH)
    data = data << 8
    data |= self.i2c.read_register(self.ADDRESS, self.REGISTER_DATAL)
    return data

  def calculate_temp(self, data):
    """Calculate temperature from register value"""
    temp = data >> 2
    temp /= 32.0
    temp -= 50.0
    return temp

  def calculate_humidity(self, data):
    """Calculate humidity from register value"""
    humidity = data >> 4
    humidity /= 16.0
    humidity -= 24.0
    return humidity

  def get_temperature(self):
    """Return temperature or -60 if there is an error"""
    self.i2c.write_register(self.ADDRESS, self.REGISTER_CONFIG, self.CONVERSION_TEMP)
    if self.wait_until_ready():
      data = self.read_data()
      return self.calculate_temp(data)

    # Error
    return -60

  def get_humidity(self):
    """Return relative humidity or -60 if there is an error"""
    self.i2c.write_register(self.ADDRESS, self.REGISTER_CONFIG, self.CONVERSION_HUMIDITY)
    if self.wait_until_ready():
      data = self.read_data()
      return self.calculate_humidity(data)
    # Error
    return -60