Knowledge Base

You can use the IO Zero 32 expansion board with the Raspberry Pi Pico development boards. We have a MicroPython library to use with the Raspberry Pi Pico at GitHub at github.com/abelectronicsuk/ABElectronics_MicroPython_Libraries

The example Python files can be found in /ABElectronics_MicroPython_Libraries/IOZero32/demos/

Connecting the IO Zero 32 to the Raspberry Pi Pico

The IO Zero 32 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 Zero 32, create a new file in thonny called IOZero32.py and copy contents from IOZero32.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 with "Run Current Command" or F5 in Thonny.

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Classes:

IOZero32(address, sda, scl)

Parameters:
address: i2c address for the target device. 0x20 to 0x27
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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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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set_pin_polarity(pin, value)

Set 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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set_port_polarity(port, value)

Set 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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set_bus_polarity(value)

Set 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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Usage

To use the IO Zero 32 library in your code, you must first import the library:

from IOZero32 import IOZero32

Next, you must initialise the IOZero32 object with the I2C address of the I/O controller chip. The default addresses for the IO Zero 32 are 0x20 and 0x21:

bus1 = IOZero32(0x20)

We will read the inputs 1 to 8 from bus 1, so set port 0 as inputs.

bus1.set_port_direction(0, 0xFF)

You can now read pin 1 with the following:

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

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