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C++ Library to use with IO Pi Raspberry Pi development board.
The example demo files can be found in /ABElectronics_CPP_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 terminal:
git clone https://github.com/abelectronicsuk/ABElectronics_CPP_Libraries.git
Classes:
IOPi(address, initialise)
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
Methods:
set_pin_direction(uint8_t pin, uint8_t direction):
Sets the IO direction for an individual pin
Parameters:
pin: 1 to 16
direction: 1 = input, 0 = output
Returns: null
get_pin_direction(uint8_t pin)
Get the IO direction for an individual pin
Parameters:
pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = input, 0 = output
set_port_direction(uint8_t port, uint8_t direction):
Sets the IO direction for the specified IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
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 port):
Get the direction from an IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)
set_bus_direction(uint16_t direction):
Sets the IO direction for all pins on the bus
Parameters:
direction: 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: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = input, 0 = output
set_pin_pullup(uint8_t pin, uint8_t 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(uint8_t pin)
Get the internal 100K pull-up resistors for an individual pin
Parameters:
pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = enabled, 0 = disabled
set_port_pullups(uint8_t port, uint8_t 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(uint8_t 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: (uint8_t) number between 0 and 255 (0xFF)
set_bus_pullups(uint16_t 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: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
write_pin(uint8_t pin, uint8_t value)
Write to an individual pin 1 - 16
Parameters:
pin: 1 to 16
value: 1 = logic high, 0 = logic low
Returns: null
write_port(uint8_t port, uint8_t 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(uint16_t 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(uint8_t pin)
Read the value of an individual pin 1 - 16
Parameters:
pin: 1 to 16
Returns: (uint8_t) 0 = logic low, 1 = logic high
read_port(uint8_t port)
Read all pins on the selected port
Parameters:
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()
Read all pins on the bus
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 pin, uint8_t polarity)
Invert the polarity of the selected pin
Parameters:
pin: 1 to 16
polarity: 0 = same logic state of the input pin, 1 = inverted logic state of the input pin
Returns: null
get_pin_polarity(uint8_t pin)
Get the polarity of the selected pin
Parameters:
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 port, uint8_t polarity)
Invert the polarity of the pins on a selected port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
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 port):
Get the polarity for the selected IO port
Parameters:
port: 0 = pins 1 to 8, 1 = pins 9 to 16
Returns: (uint8_t) number between 0 and 255 (0xFF)
invert_bus(uint16_t polarity)
Invert the polarity of the pins on the bus
Parameters:
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()
Get the polarity of the pins on the bus
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 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
set_interrupt_polarity(uint8_t 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: (uint8_t) 1 = Active-high. 0 = Active-low.
set_interrupt_type(uint8_t port, uint8_t 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(uint8_t 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: (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 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 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(uint8_t 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: (uint8_t) number between 0 and 255 (0xFF)
set_interrupt_on_pin(uint8_t pin, uint8_t 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(uint8_t pin)
Gets whether the interrupt is enabled for the selected pin
Parameters:
pin: pin to read, 1 to 16
Returns: (uint8_t) 1 = enabled, 0 = disabled
set_interrupt_on_port(uint8_t port, uint8_t 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(uint8_t port):
Gets whether the interrupts are enabled for the selected port
Parameters:
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(uint16_t 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: (uint16_t) 16-bit number 0 to 65535 (0xFFFF). For each bit 1 = enabled, 0 = disabled
read_interrupt_status(uint8_t 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: (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 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: (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()
Set the interrupts A and B to 0
Parameters: null
Returns: null
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