I2C

Code Example

from periphery import I2C

# Open i2c-0 controller
i2c = I2C("/dev/i2c-0")

# Read byte at address 0x100 of EEPROM at 0x50
msgs = [I2C.Message([0x01, 0x00]), I2C.Message([0x00], read=True)]
i2c.transfer(0x50, msgs)
print("0x100: 0x%02x" % msgs[1].data[0])

i2c.close()

API

class periphery.I2C(devpath)

Bases: object

Instantiate an I2C object and open the i2c-dev device at the specified path.

Parameters:devpath (str) – i2c-dev device path. Returns:I2C object. Return type:I2C Raises:I2CError – if an I/O or OS error occurs.

transfer(address, messages)

Transfer messages to the specified I2C address. Modifies the messages array with the results of any read transactions.

Parameters:

• address (int) – I2C address.
• messages (list) – list of I2C.Message messages.

Raises:

• I2CError – if an I/O or OS error occurs.
• TypeError – if messages type is not list.
• ValueError – if messages length is zero, or if message data is not valid bytes.

close()

Close the i2c-dev I2C device.

Raises:I2CError – if an I/O or OS error occurs.

fd

Get the file descriptor of the underlying i2c-dev device.

Type:int

devpath

Get the device path of the underlying i2c-dev device.

Type:str

class Message(data, read=False, flags=0)

Instantiate an I2C Message object.

Parameters:

• data (bytes, bytearray, list) – a byte array or list of 8-bit integers to write.
• read (bool) – specify this as a read message, where data serves as placeholder bytes for the read.
• flags (int) – additional i2c-dev flags for this message.

Returns:

Message object.

Return type:

Message

Raises:

TypeError – if data, read, or flags types are invalid.

class periphery.I2CError

Bases: exceptions.IOError

Base class for I2C errors.