htu21df.lua

htu21df= {
     dev_addr = 0x40,
     id = 0,
     init = function (self, sda, scl)
               self.id = 0
               i2c.setup(self.id, sda, scl, i2c.SLOW)
     end,
     read_reg = function(self, dev_addr, reg_addr)
          i2c.start(self.id)
          i2c.address(self.id, dev_addr ,i2c.TRANSMITTER)
          i2c.write(self.id,reg_addr)
          i2c.stop(self.id)
          i2c.start(self.id)
          i2c.address(self.id, dev_addr,i2c.RECEIVER)
          c=i2c.read(self.id,2)
          i2c.stop(self.id)
          return c
    end,
    

    readTemp = function(self)
          h, l = string.byte(self:read_reg(0x40, 0xE3), 1, 2)
          h1=bit.lshift(h,8)
          rawtemp = bit.band(bit.bor(h1,l),0xfffc)
          temp = ((rawtemp/65536)*175.72)-46.85
          return temp
    end,
    readHum = function(self)
          h,l = string.byte(self:read_reg(0x40,0xE5),1,2)
          h1=bit.lshift(h,8)
          rawhum = bit.band(bit.bor(h1,1),0xfffc)
          hum = ((rawhum/65536)*125.0)-6.0
          return hum
     end
     }