Arietta sysfs GPIO wrapper for node.js based on node-native-gpio
npm install arietta-gpioarietta-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.
Install arietta-gpio with npm:
$ npm install arietta-gpio
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);
}
}
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.
Copyright © 2013 Bodo Kaiser
Copyright © 2015 Alberto Garbui
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