Knowledge Base

The IO Pi Plus can be used with the Raspberry Pi Pico available at www.raspberrypi.com/products/raspberry-pi-pico/

We have a MicroPython library to use with the Raspberry Pi Pico at github.com/abelectronicsuk/ABElectronics_MicroPython_Libraries.

The example Python files can be found in /ABElectronics_MicroPython_Libraries/IOPi/demos/

Connecting the IO Pi Plus to the Raspberry Pi Pico

The IO Pi Plus library uses the following pins on the Raspberry Pi Pico board.

Pico Pin	Pico GPIO	Function	Pi Pin	Pi GPIO
26	20	I2C SDA	3	GPIO 2
27	21	I2C SCL	5	GPIO 3
40	VBUS	5V	2	5V Power
38	GND	GND	6	Ground
36	3V3(OUT)	3V3	1	3v3 Power

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Wiring Diagram:

Downloading and Installing the library

To download to your Raspberry Pi, type in the terminal:

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

To install the MicroPython Library, use the Thonny Python IDE from https://thonny.org/

Create a file for your chosen board and copy the contents of the Python file into that board's directory. For example, for the IO Pi Plus, create a new file in thonny called IOPi.py, copy contents from IOPi.py into the new file, and save it onto the Raspberry Pi Pico board.

Create a second file where your main program will reside and import the board library at the program's top.

from IOPi import IOPi

Run with "Run Current Command" or F5 in Thonny.

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Classes:

IOPi(address, initialise, sda, scl)

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
sda (optional): I2C SDA pin. If no value is set, the class will default to pin 20.
scl (optional): I2C SCL pin. If no value is set, the class will default to pin 21.

Functions:

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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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)

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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

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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

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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

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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

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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

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read_pin(pin)

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

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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

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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

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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

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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

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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

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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)

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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

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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

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mirror_interrupts(value)

Sets whether the interrupt pins INT A and INT B are independently connected to each port or internally connected together
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

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set_interrupt_polarity(value)

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

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get_interrupt_polarity()

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

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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

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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, and 0 = interrupt fires on state change.

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set_interrupt_defaults(port, value)

These bits set the compare value for pins configured for interrupt-on-change on the selected port.
An interrupt occurs if the associated pin level is the opposite of the register bit.
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

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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)

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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

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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

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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

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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

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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

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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

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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

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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

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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 Plus 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 the following:

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

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