IO Pi Node JS Library

Node.js Library to use with IO Pi Raspberry Pi development board.

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.

Install

To download to your Raspberry Pi type in the terminal:

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

The IO Pi library is located in the /lib/iopi/ directory

The example files are located in the /examples/iopi/ directory

The IO Pi library requires the i2c-bus library to run.

Install i2c-bus from npm package repository i2c-bus with

npm install i2c-bus

Classes:

IoPi(address, initialise)

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

Functions:

setPinDirection(pin, direction):

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

getPinDirection(pin)

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

setPortDirection(port, direction): 

Sets the IO direction for the specified IO port
Parameters:
port: (number) 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

getPortDirection(port): 

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

setBusDirection(direction): 

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

getBusDirection()

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

setPinPullup(pin, value)

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

getPinPullup(pin)

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

setPortPullups(port, value)

Set the internal 100K pull-up resistors for the selected IO port
Parameters:
port: (number) 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

getPortPullups(port): 

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

setBusPullups(value)

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

getBusPullups()

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

writePin(pin, value)

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

writePort(port, value)

Write to all pins on the selected port
Parameters:
port: (number) 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

writeBus(value)

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

readPin(pin)

Read the value of an individual pin 1 - 16
Parameters:
pin: (number) 1 to 16
Returns: (uint8_t) 0 = logic low, 1 = logic high

readPort(port)

Read all pins on the selected port
Parameters:
port: (number) 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

readBus()

Read all pins on the bus
Returns: (number) 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

invertPin(pin, polarity)

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

getPinPolarity(pin)

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

invertPort(port, polarity)

Invert the polarity of the pins on a selected port
Parameters:
port: (number) 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

getPortPolarity(port): 

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

invertBus(polarity)

Invert the polarity of the pins on the bus
Parameters:
polarity: (number) 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

getBusPolarity()

Get the polarity of the pins on the bus
Returns: (number) 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

mirrorInterrupts(value)

Sets whether the interrupt pins INT A and INT B are independently connected to each port or internally connected
Parameters:
value: (number) 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

setInterruptPolarity(value)

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

getInterruptPolarity()

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

setInterruptType(port, value)

Sets the type of interrupt for each pin on the selected port
Parameters:
port: (number) 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

getInterruptType(port): 

Get the type of interrupt for each pin on the selected port
Parameters:
port: (number) 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

setInterruptDefaults(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 of the register bit, an interrupt occurs.
Parameters:
port: (number) 0 = pins 1 to 8, 1 = pins 9 to 16
value: (number) 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

getInterruptDefaults(port): 

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

setInterruptOnPin(pin, value)

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

getInterruptOnPin(pin)

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

setInterruptOnPort(port, value)

Enable interrupts for the pins on the selected port
Parameters:
port: (number) 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

getInterruptOnPort(port): 

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

setInterruptOnBus(value)

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

getInterruptOnBus()

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

readInterruptStatus(port)

Read the interrupt status for the pins on the selected port
Parameters:
port: (number) 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

readInterruptCapture(port)

Read the value from the selected port at the time of the last interrupt trigger
Parameters:
port: (number) 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

resetInterrupts()

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:

var iopi = require('../../lib/iopi/iopi');

Next, you must initialise the IO object

var bus1 = new IoPi(0x20);

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

bus1.setPortDirection(0, 0xFF);
bus1.setPortPullups(0, 0xFF);

You can now read pin 1 with:

console.log('Pin 1: %d', bus1.readPin(1));