sht30.py 文件源码

def send_cmd(self, cmd_request, response_size=6, read_delay_ms=100):
        """
        Send a command to the sensor and read (optionally) the response
        The responsed data is validated by CRC
        """
        try:
            self.i2c.start(); 
            self.i2c.writeto(self.i2c_addr, cmd_request); 
            if not response_size:
                self.i2c.stop();    
                return
            time.sleep_ms(read_delay_ms)
            data = self.i2c.readfrom(self.i2c_addr, response_size) 
            self.i2c.stop(); 
            for i in range(response_size//3):
                if not self._check_crc(data[i*3:(i+1)*3]): # pos 2 and 5 are CRC
                    raise SHT30Error(SHT30Error.CRC_ERROR)
            if data == bytearray(response_size):
                raise SHT30Error(SHT30Error.DATA_ERROR)
            return data
        except OSError as ex:
            if 'I2C' in ex.args[0]:
                raise SHT30Error(SHT30Error.BUS_ERROR)
            raise ex