def _read_register(self, reg):
        """Read 16 bit register value."""
        self.buf[0] = reg
        with self.i2c_device as i2c:
            i2c.write(self.buf, end=1, stop=False)
            i2c.readinto(self.buf, end=2)
        return self.buf[0] << 8 | self.buf[1]
Read 16 bit register value.