sht31.py

from microbit import i2c,sleep
R_HIGH=1
R_MEDIUM=2
R_LOW=3
class SHT31:
  _map_cs_r={True:{R_HIGH :b'\x2c\x06',R_MEDIUM :b'\x2c\x0d',R_LOW:b'\x2c\x10'},False:{R_HIGH :b'\x24\x00',R_MEDIUM :b'\x24\x0b',R_LOW:b'\x24\x16'}}
  def __init__(self,addr=0x44):
    i2c.init(freq=20000)
    self._addr=addr
  def _send(self,buf):i2c.write(self._addr,buf)
  def _recv(self,count):return i2c.read(self._addr,count)
  def _raw_temp_humi(self,r=R_HIGH,cs=True):
    if r not in (R_HIGH,R_MEDIUM,R_LOW):raise ValueError('Wrong repeatabillity value given!')
    self._send(self._map_cs_r[cs][r])
    sleep(50)
    raw=self._recv(6)
    return (raw[0]<<8)+raw[1],(raw[3]<<8)+raw[4]
  def get_temp_humi(self,data='t',resolution=R_HIGH,clk_stretch=True,celsius=True):
    t,h=self._raw_temp_humi(resolution,clk_stretch)
    sleep(50)
    if celsius:temp=-45+(175*(t/65535))
    else:temp=-49+(315*(t/65535))
    if data=='t':return temp
    elif data=='h':return 100*(h/65535)
    else:return None