API Documentation

Channel:

class sensirion_i2c_adapter.channel.TxRxChannel

This is the abstract base class for any channel. A channel is a transportation medium to transfer data from any source to any destination

write_read(tx_bytes, payload_offset, response, device_busy_delay=0.0, slave_address=None, ignore_errors=False)

Transfers the data to and from sensor.

Parameters:
  • tx_bytes – Raw bytes to be transmitted
  • payload_offset – The data my contain a header that needs to be left untouched, pushing the date through the protocol stack. The Payload offset points to the end of the header and the beginning of the data
  • response – The response is an object that is able to unpack a raw response. It has to provide a method ‘interpret_response.
  • device_busy_delay – Indication how long the receiver of the message will be busy until processing of the data has been completed.
  • slave_address – Used for i2c addressing. Denotes the i2c address of the receiving slave
  • ignore_errors – Some transfers may generate an exception even when they execute properly. In these situations the exception is swallowed and an empty result is returned
Returns:

Return a tuple of the interpreted data or None if there is no response at all
class sensirion_i2c_adapter.channel.TxRxRequest(channel, tx_bytes=None, response=None, device_busy_delay=0.0, receive_length=0)

This class is an adapter to the class I2cConnection. It keeps compatibility with the SensirionI2cCommand

I2C-Channel

class sensirion_i2c_adapter.i2c_channel.I2cChannel(connection, slave_address=0, crc=None)

This is the concrete channel implementation to be used with I2cConnection of the package sensirion-i2c-driver

strip_protocol(data)

Validates the CRCs of the received data from the device and returns the data with all CRCs removed.

Parameters:data (bytes) – Received raw bytes from the read operation.
Returns:The received bytes without crc, or None if there is no data received.
Return type:bytes or None
Raises:I2cChecksumError – If a received CRC was wrong.
write_read(tx_bytes, payload_offset, response, device_busy_delay=0.0, slave_address=None, ignore_errors=False)

Transfers the data to and from sensor.

Parameters:
  • tx_bytes – Raw bytes to be transmitted
  • payload_offset – The data my contain a header that needs to be left untouched, pushing the date through the protocol stack. The Payload offset points to the end of the header and the beginning of the data
  • response – The response is an object that is able to unpack a raw response. It has to provide a method ‘interpret_response.
  • device_busy_delay – Indication how long the receiver of the message will be busy until processing of the data has been completed.
  • slave_address – Used for i2c addressing. Denotes the i2c address of the receiving slave
  • ignore_errors – Some transfers may generate an exception even when they execute properly. In these situations the exception is swallowed and an empty result is returned
Returns:

Return a tuple of the interpreted data or None if there is no response at all

Transfer:

class sensirion_i2c_adapter.transfer.RxData(descriptor=None)

Descriptor for data to be received

class sensirion_i2c_adapter.transfer.Transfer

A transfer abstracts the data that is exchanged between host and sensor

class sensirion_i2c_adapter.transfer.TxData(cmd_id, descriptor, device_busy_delay=0.0, slave_address=None, ignore_ack=False)

Models the tx data that is exchanged. It it primarily a descriptor that knows how to convert structured data into a list of raw bytes

sensirion_i2c_adapter.transfer.execute_transfer(channel: sensirion_i2c_adapter.channel.TxRxChannel, *args)

Executes a transfer consisting of one or more Transfer objects. :param channel: The channel that is used to transfer the data :param args: a variable list of transfers to be transmitted :return: a tuple of data if the last transfer has a response