IO Pi C Library

C Library to use with IO Pi Raspberry Pi development board.

The example C programs can be found in /ABElectronics_C_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_C_Libraries.git

Functions

IOPi_init(uint8_t address, uint8_t reset = 1)

Initialise the MCP32017 IO chip with default values: ports are inputs, pull-up resistors are disabled and ports are not inverted.
Parameter: (uint8_t) address: i2c address for the target device. 0x20 to 0x27
Parameter: (uint8_t) reset: If set to 1 the IO Pi will reset to default values. Ports are inputs, pull-up resistors are disabled and ports are not inverted.
Returns: null

set_pin_direction(uint8_t address, uint8_t pin, uint8_t direction):

Sets the IO direction for an individual pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: 1 to 16
Parameter: (uint8_t) direction: 1 = input, 0 = output
Returns: null

get_pin_direction(uint8_t address, uint8_t pin)

Get the IO direction for an individual pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = input, 0 = output

set_port_direction(uint8_t address, uint8_t port, uint8_t direction): 

Sets the IO direction for the specified IO port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) direction: 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(uint8_t address, uint8_t port): 

Get the direction from an IO port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)

set_bus_direction(uint8_t address, uint16_t direction): 

Sets the IO direction for all pins on the bus
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) direction: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = input, 0 = output
Returns: null

get_bus_direction(uint8_t address)

Get the direction for an IO bus
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = input, 0 = output

set_pin_pullup(uint8_t address, uint8_t pin, uint8_t value)

Set the internal 100K pull-up resistors for an individual pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: pin to update, 1 to 16
Parameter: (uint8_t) value: 1 = enabled, 0 = disabled
Returns: null

get_pin_pullup(uint8_t address, uint8_t pin)

Get the internal 100K pull-up resistors for an individual pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = enabled, 0 = disabled

set_port_pullups(uint8_t address, uint8_t port, uint8_t value)

Set the internal 100K pull-up resistors for the selected IO port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) 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(uint8_t address, uint8_t port): 

Get the internal pull-up status for the selected IO port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)

set_bus_pullups(uint8_t address, uint16_t value)

Set internal 100K pull-up resistors for an IO bus
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
Returns: null

get_bus_pullups(uint8_t address)

Get the internal 100K pull-up resistors for an IO bus
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled

write_pin(uint8_t address, uint8_t pin, uint8_t value)

Write to an individual pin 1 - 16
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: 1 to 16
Parameter: (uint8_t) value: 1 = logic high, 0 = logic low
Returns: null

write_port(uint8_t address, uint8_t port, uint8_t value)

Write to all pins on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) 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(uint8_t address, uint16_t value)

Write to all pins on the selected bus
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = logic high, 0 = logic low
Returns: null

read_pin(uint8_t address, uint8_t pin)

Read the value of an individual pin 1 - 16
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: 1 to 16
Returns: (uint8_t) 0 = logic low, 1 = logic high

read_port(uint8_t address, uint8_t port)

Read all pins on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) 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(uint8_t address)

Read all pins on the bus
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint16_t) 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(uint8_t address, uint8_t pin, uint8_t polarity)

Invert the polarity of the selected pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: 1 to 16
Parameter: (uint8_t) polarity: 0 = same logic state of the input pin, 1 = inverted logic state of the input pin
Returns: null

get_pin_polarity(uint8_t address, uint8_t pin)

Get the polarity of the selected pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: pin to read, 1 to 16
Returns: (uint8_t) 0 = same logic state of the input pin, 1 = inverted logic state of the input pin

invert_port(uint8_t address, uint8_t port, uint8_t polarity)

Invert the polarity of the pins on a selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) polarity: 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(uint8_t address, uint8_t port): 

Get the polarity for the selected IO port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)

invert_bus(uint8_t address, uint16_t polarity)

Invert the polarity of the pins on the bus
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) polarity: 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(uint8_t address)

Get the polarity of the pins on the bus
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint16_t) 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(uint8_t address, uint8_t value)

Sets whether the interrupt pins INT A and INT B are independently connected to each port or internally connected together
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) 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(uint8_t address, uint8_t value)

Sets the polarity of the INT output pins
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) value: 0 = Active Low, 1 = Active High
Returns: null

get_interrupt_polarity(uint8_t address)

Get the polarity of the INT output pins
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint8_t) 1 = Active-high. 0 = Active-low.

set_interrupt_type(uint8_t address, uint8_t port, uint8_t value)

Sets the type of interrupt for each pin on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) 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(uint8_t address, uint8_t port): 

Get the type of interrupt for each pin on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) 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(uint8_t address, uint8_t port, uint8_t 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 of the register bit, an interrupt occurs.
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) 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(uint8_t address, uint8_t port): 

Get the interrupt default value for each pin on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)

set_interrupt_on_pin(uint8_t address, uint8_t pin, uint8_t value)

Enable interrupts for the selected pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: 1 to 16
Parameter: (uint8_t) value: 0 = interrupt disabled, 1 = interrupt enabled
Returns: null

get_interrupt_on_pin(uint8_t address, uint8_t pin)

Gets whether the interrupt is enabled for the selected pin
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = enabled, 0 = disabled

set_interrupt_on_port(uint8_t address, uint8_t port, uint8_t value)

Enable interrupts for the pins on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Parameter: (uint8_t) 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(uint8_t address, uint8_t port): 

Gets whether the interrupts are enabled for the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF). For each bit 1 = enabled, 0 = disabled

set_interrupt_on_bus(uint8_t address, uint16_t value)

Enable interrupts for the pins on the bus
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) value: 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
Returns: null

get_interrupt_on_bus(uint8_t address)

Gets whether the interrupts are enabled for the bus
Parameter: (uint8_t) address: I2C address for the target device
Returns: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled

read_interrupt_status(uint8_t address, uint8_t port)

Read the interrupt status for the pins on the selected port
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) 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(uint8_t address, uint8_t port)

Read the value from the selected port at the time of the last interrupt trigger
Parameter: (uint8_t) address: I2C address for the target device
Parameter: (uint8_t) port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) 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(uint8_t address)

Set the interrupts A and B to 0
Parameter: (uint8_t) address: I2C address for the target device
Returns: null