arietta-gpio

arietta-gpio is a sysfs General Purpose Input Output wrapper for node.js. It gives you the ability to control GPIO of the Acmesystems Arietta board in a simple object orientated manner. Visit AcmeSystems official site for more informations about this hardware.

Installation

Install arietta-gpio with npm:

$ npm install arietta-gpio

Preview

var arietta = require('arietta-gpio');

var button = new arietta.GPIO(81);  //81 is the kernel ID for the onboard pushbutton
var led = new arietta.GPIO(64);		//64 is the kernel ID for pin 39 (PC0)

led
    .direction(arietta.GPIO.OUT)
    .value(arietta.GPIO.LOW)
    ;
	  
button
    .direction(arietta.GPIO.IN)
    ;
	
while(true){	
	if(button.value() != arietta.GPIO.HIGH){
		led.value(arietta.GPIO.HIGH);
	}else{
		led.value(arietta.GPIO.LOW);
	}
}

Documentation

Class: GPIO

The GPIO function prototype is a C++ add-on which abstracts a GPIO device as instancable object. There are some class constants defined which should be used for setting values (see below).

GPIO.IN

Direction constant used to determinate that our GPIO device listens for incoming signals. While a device is set to IN we can only read and not write to it.

GPIO.OUT

Direction constant used to determinate that our GPIO device writes outgoing signals. While a device is set to OUT we can read and set the current value.

GPIO.LOW

Value constant for off state of a GPIO device.

GPIO.HIGH

Value constant for on state of a GPIO device.

new GPIO(id)

var gpio23 = new GPIO(23);

Creates a new instance of the GPIO class. Internally it will do a GPIO export if neccessary and open the GPIO's value and direction file descriptor to reduce syscalls. The C++ deconstructor ensures that the file descriptors are closed and the GPIO device is getting unexported (this would not have been possible with plain JavaScript).

gpio.direction([value])

if (gpio23.direction() === GPIO.OUT)
    gpio23.direction(GPIO.IN);

Returns the current GPIO direction mode if no arguments supplied else it will check if the first argument is a valid constant and then will set this as GPIO direction.

gpio.activeLow([value])

if (gpio23.activeLow() === GPIO.HIGH)
    gpio23.activeLow(GPIO.LOW);

Some circuits use a GPIO the other way around: This means the GPIO enables the circuit when it switches to LOW. In order to keep semantics of value you can switch the active mode by using activeLow with either LOW or HIGH.

gpio.value([value])

while (gpio23.value() != GPIO.HIGH)
    // wait until GPIO value changes to HIGH

// use GPIO as output device
gpio23.direction(GPIO.OUT).value(GPIO.LOW);

Returns the current GPIO value if no arguments supplied else it will check if the first argument is a valid constant and then will use this as GPIO value.

License

Copyright © 2013 Bodo Kaiser [email protected]

Copyright © 2015 Alberto Garbui [email protected]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.