IO Pi Python Library

Python Library to use with IO Pi Plus Raspberry Pi development board.

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

Note: Microchip recommends that pin 8 (GPA7) and pin 16 (GPB7) are used as outputs only. This change was made for revision D MCP23017 chips manufactured after June 2020. See the MCP23017 datasheet for more information.

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 IO Pi library is located in the IOPi 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

Classes:

IOPi(address, initialise, bus)

Parameters:
address: i2c address for the target device. 0x20 to 0x27
initialise (optional): True = direction set as inputs, pull-ups disabled, ports not inverted. False = device state unaltered., defaults to True
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.

Functions:

set_pin_direction(pin, value):

Sets the IO direction for an individual pin
Parameters:
pin: 1 to 16
value: 1 = input, 0 = output
Returns: null

get_pin_direction(pin)

Get the IO direction for an individual pin
Parameters:
pin: pin to read, 1 to 16
Returns: 1 = input, 0 = output

set_port_direction(port, value): 

Sets the IO direction for the specified IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = input, 0 = output
Returns: null

get_port_direction(port): 

Get the direction from an IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF)

set_bus_direction(value): 

Sets the IO direction for all pins on the bus
Parameters:
value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = input, 0 = output
Returns: null

get_bus_direction()

Get the direction for an IO bus
Returns: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = input, 0 = output

set_pin_pullup(pin, value)

Set the internal 100K pull-up resistors for an individual pin
Parameters:
pin: pin to update, 1 to 16 value: 1 = enabled, 0 = disabled
Returns: null

get_pin_pullup(pin)

Get the internal 100K pull-up resistors for an individual pin
Parameters:
pin: pin to read, 1 to 16
Returns: 1 = enabled, 0 = disabled

set_port_pullups(port, value)

Set the internal 100K pull-up resistors for the selected IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = Enabled, 0 = Disabled
Returns: null

get_port_pullups(port): 

Get the internal pull-up status for the selected IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF)

set_bus_pullups(value)

Set internal 100K pull-up resistors for an IO bus
Parameters:
value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
Returns: null

get_bus_pullups()

Get the internal 100K pull-up resistors for an IO bus
Returns: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled

write_pin(pin, value)

Write to an individual pin 1 - 16
Parameters:
pin: 1 to 16
value: 1 = logic high, 0 = logic low
Returns: null

write_port(port, value)

Write to all pins on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = logic high, 0 = logic low
Returns: null

write_bus(value)

Write to all pins on the selected bus
Parameters:
value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = logic high, 0 = logic low
Returns: null

read_pin(pin)

Read the value of an individual pin 1 - 16
Parameters:
pin: 1 to 16
Returns: 0 = logic low, 1 = logic high

read_port(port)

Read all pins on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 0 = logic low, 1 = logic high

read_bus()

Read all pins on the bus
Returns: 16-bit number 0 to 65535 (0xFFFF) Each bit in the 16-bit number represents a pin on the port. 0 = logic low, 1 = logic high

invert_pin(pin, value)

Invert the polarity of the selected pin
Parameters:
pin: 1 to 16
value: 0 = same logic state of the input pin, 1 = inverted logic state of the input pin
Returns: null

get_pin_polarity(pin)

Get the polarity of the selected pin
Parameters:
pin: pin to read, 1 to 16
Returns: 0 = same logic state of the input pin, 1 = inverted logic state of the input pin

invert_port(port, value)

Invert the polarity of the pins on a selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 0 = same logic state of the input pin, 1 = inverted logic state of the input pin
Returns: null

get_port_polarity(port): 

Get the polarity for the selected IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF)

invert_bus(value)

Invert the polarity of the pins on the bus
Parameters:
value: 16-bit number 0 to 65535 (0xFFFF). For each bit 0 = same logic state of the input pin, 1 = inverted logic state of the input pin
Returns: null

get_bus_polarity()

Get the polarity of the pins on the bus
Returns: 16-bit number 0 to 65535 (0xFFFF). For each bit 0 = same logic state of the input pin, 1 = inverted logic state of the input pin

mirror_interrupts(value)

Sets whether the interrupt pins INT A and INT B are independently connected to each port or internally connected
Parameters:
value: 1 = The INT pins are internally connected, 0 = The INT pins are not connected. INT A is associated with PortA and INT B is associated with PortB
Returns: null

set_interrupt_polarity(value)

Sets the polarity of the INT output pins
Parameters:
value: 0 = Active Low, 1 = Active High
Returns: null

get_interrupt_polarity()

Get the polarity of the INT output pins
Returns: 1 = Active-high. 0 = Active-low.

set_interrupt_type(port, value)

Sets the type of interrupt for each pin on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = interrupt is fired when the pin matches the default value, 0 = the interrupt is fired on state change
Returns: null

get_interrupt_type(port): 

Get the type of interrupt for each pin on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF)
For each bit 1 = interrupt is fired when the pin matches the default value, 0 = interrupt fires on state change

set_interrupt_defaults(port, value)

These bits set the compare value for pins configured for interrupt-on-change on the selected port.
If the associated pin level is the opposite from the register bit, an interrupt occurs.
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16, value: compare value between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port.
Returns: null

get_interrupt_defaults(port): 

Get the interrupt default value for each pin on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF)

set_interrupt_on_pin(pin, value)

Enable interrupts for the selected pin
Parameters:
pin: 1 to 16
value: 0 = interrupt disabled, 1 = interrupt enabled
Returns: null

get_interrupt_on_pin(pin)

Gets whether the interrupt is enabled for the selected pin
Parameters:
pin: pin to read, 1 to 16
Returns: 1 = enabled, 0 = disabled

set_interrupt_on_port(port, value)

Enable interrupts for the pins on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
value: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port.
Returns: null

get_interrupt_on_port(port): 

Gets whether the interrupts are enabled for the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 (0xFF). For each bit 1 = enabled, 0 = disabled

set_interrupt_on_bus(value)

Enable interrupts for the pins on the bus
Parameters:
value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
Returns: null

get_interrupt_on_bus()

Gets whether the interrupts are enabled for the bus
Returns: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled

read_interrupt_status(port)

Read the interrupt status for the pins on the selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = Enabled, 0 = Disabled

read_interrupt_capture(port)

Read the value from the selected port at the time of the last interrupt trigger
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: number between 0 and 255 or 0x00 and 0xFF. Each bit in the 8-bit number represents a pin on the port. 1 = Enabled, 0 = Disabled

reset_interrupts()

Set the interrupts A and B to 0
Parameters: null
Returns: null

Usage

To use the IO Pi library in your code you must first import the library:

from IOPi import IOPi

Next, you must initialise the IO object with the I2C address of the I/O controller chip. The default addresses for the IO Pi are 0x20 and 0x21:

bus1 = IOPI(0x20)

We will read the inputs 1 to 8 from bus 2 so set port 0 as inputs and enable the internal pull-up resistors

bus1.set_port_direction(0, 0xFF)
bus1.set_port_pullups(0, 0xFF)

You can now read pin 1 with:

print('Pin 1: ' + str(bus1.read_pin(1)))