smbus2

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smbus2 - A drop-in replacement for smbus-cffi/smbus-python

class smbus2.SMBus(bus=None, force=False)
block_process_call(i2c_addr, register, data, force=None)

Executes a SMBus Block Process Call, sending a variable-size data block and receiving another variable-size response

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to read/write to
  • data (list) – List of bytes
  • force (Boolean) –
Returns:

List of bytes

Return type:

list

close()

Close the i2c connection.

enable_pec(enable=True)

Enable/Disable PEC (Packet Error Checking) - SMBus 1.1 and later

Parameters:enable (Boolean) –
i2c_rdwr(*i2c_msgs)

Combine a series of i2c read and write operations in a single transaction (with repeated start bits but no stop bits in between).

This method takes i2c_msg instances as input, which must be created first with i2c_msg.read() or i2c_msg.write().

Parameters:i2c_msgs (i2c_msg) – One or more i2c_msg class instances.
Return type:None
open(bus)

Open a given i2c bus.

Parameters:bus (int or str) – i2c bus number (e.g. 0 or 1) or an absolute file path (e.g. ‘/dev/i2c-42’).
Raises:TypeError – if type(bus) is not in (int, str)
pec

Get and set SMBus PEC. 0 = disabled (default), 1 = enabled.

process_call(i2c_addr, register, value, force=None)

Executes a SMBus Process Call, sending a 16-bit value and receiving a 16-bit response

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to read/write to
  • value (int) – Word value to transmit
  • force (Boolean) –
Return type:

int

read_block_data(i2c_addr, register, force=None)

Read a block of up to 32-bytes from a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Start register
  • force (Boolean) –
Returns:

List of bytes

Return type:

list

read_byte(i2c_addr, force=None)

Read a single byte from a device.

Return type:

int

Parameters:
  • i2c_addr (int) – i2c address
  • force (Boolean) –
Returns:

Read byte value

read_byte_data(i2c_addr, register, force=None)

Read a single byte from a designated register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to read
  • force (Boolean) –
Returns:

Read byte value

Return type:

int

read_i2c_block_data(i2c_addr, register, length, force=None)

Read a block of byte data from a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Start register
  • length (int) – Desired block length
  • force (Boolean) –
Returns:

List of bytes

Return type:

list

read_word_data(i2c_addr, register, force=None)

Read a single word (2 bytes) from a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to read
  • force (Boolean) –
Returns:

2-byte word

Return type:

int

write_block_data(i2c_addr, register, data, force=None)

Write a block of byte data to a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Start register
  • data (list) – List of bytes
  • force (Boolean) –
Return type:

None

write_byte(i2c_addr, value, force=None)

Write a single byte to a device.

Parameters:
  • i2c_addr (int) – i2c address
  • value (int) – value to write
  • force (Boolean) –
write_byte_data(i2c_addr, register, value, force=None)

Write a byte to a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to write to
  • value (int) – Byte value to transmit
  • force (Boolean) –
Return type:

None

write_i2c_block_data(i2c_addr, register, data, force=None)

Write a block of byte data to a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Start register
  • data (list) – List of bytes
  • force (Boolean) –
Return type:

None

write_quick(i2c_addr, force=None)

Perform quick transaction. Throws IOError if unsuccessful. :param i2c_addr: i2c address :type i2c_addr: int :param force: :type force: Boolean

write_word_data(i2c_addr, register, value, force=None)

Write a single word (2 bytes) to a given register.

Parameters:
  • i2c_addr (int) – i2c address
  • register (int) – Register to write to
  • value (int) – Word value to transmit
  • force (Boolean) –
Return type:

None

class smbus2.i2c_msg

As defined in i2c.h.

addr

Structure/Union member

buf

Structure/Union member

flags

Structure/Union member

len

Structure/Union member

static read(address, length)

Prepares an i2c read transaction.

Parameters:
  • address – Slave address.
  • length – Number of bytes to read.
Type:

address: int

Type:

length: int

Returns:

New i2c_msg instance for read operation.

Return type:

i2c_msg

static write(address, buf)

Prepares an i2c write transaction.

Parameters:
  • address (int) – Slave address.
  • buf (list) – Bytes to write. Either list of values or str.
Returns:

New i2c_msg instance for write operation.

Return type:

i2c_msg