I2C Switch Python Library

Python Library to use with I2C Switch Raspberry Pi development board.

The example python files can be found in /ABElectronics_Python_Libraries/I2CSwitch/demos

Downloading and Installing the library

To download to your Raspberry Pi type in the terminal:

git clone https://github.com/abelectronicsuk/ABElectronics_Python_Libraries.git

To install the python library navigate into the ABElectronics_Python_Libraries folder and run:

For Python 2.7:

sudo python setup.py install

For Python 3:

sudo python3 setup.py install

If you have PIP installed you can install the library directly from GitHub with the following command:

For Python 2.7:

sudo python2.7 -m pip install git+https://github.com/abelectronicsuk/ABElectronics_Python_Libraries.git

For Python 3:

sudo python3 -m pip install git+https://github.com/abelectronicsuk/ABElectronics_Python_Libraries.git

The I2C Switch library is located in the I2CSwitch directory

The library requires smbus2 or python-smbus to be installed.

For Python 2.7:

sudo pip install smbus2

For Python 3:

sudo pip3 install smbus2

Class: I2CSwitch

I2CSwitch(address, bus)

The I2CSwitch class provides control over the I2C Switch outputs on the PCA9546A controller. Functions include setting and getting the I2C channel and resetting the switch.

Parameters:
address: Device i2c address. Supported I2C addresses are 0x70 to 0x77. defaults to 0x70
bus (optional): I2C bus number (integer). If no value is set the class will try to find the i2c bus automatically using the device name.

Initialise with the I2C address for the I2C Switch.

i2cswitch = I2CSwitch(0x70)

Functions:

switch_channel(channel) 

Switch on the selected channel and switch off all other channels.
Parameters: channel - 1 to 4.
Returns: null

set_channel_state(channel, state) 

Set the state for the selected channel. All other channels remain in their previous state.
Parameters:
channel - 1 to 4
state - True or False. True = channel on, False = channel off.
Returns: null

get_channel_state(channel) 

Get the state for the selected channel.
Parameters: channel - 1 to 4
Returns: True or False. True = channel on, False = channel off.

reset() 

Reset the PCA9546A I2C switch. Resetting allows the PCA9546A to recover from a situation in which one of the downstream I2C buses is stuck in a low state. All channels will be set to an off-state. Returns: null

Usage

To use the I2C Switch class in your code you must first import the class:

from I2CSwitch import I2CSwitch

Next, you must initialise the I2CSwitch object:

i2cswitch = I2CSwitch(0x70)

Set the I2C switch to channel 2

i2cswitch.switch_channel(2)