About

Simple wrapper for the PiFace Digital and NodeJS (v4+ or v5+)

Installation

Note: recent Kernel versions need Device-Tree to be disabled in order to use SPI.

• Install NodeJS

Follow the instructions available here: https://nodejs.org/en/download/package-manager/

(Optional) Update npm and node-gyp

npm install -g npm@latest
npm install -g node-gyp@latest

• Download, build and install the C libraries

sudo apt-get install automake libtool git

git clone https://github.com/piface/libmcp23s17.git
cd libmcp23s17
make && sudo make install

git clone https://github.com/piface/libpifacedigital.git
cd libpifacedigital
make && sudo make install

• Enable SPI kernel module in raspi configuration (located in interface options -> SPI, eventually reboot is needed )

sudo raspi-config

• Install the PiFace NodeJS module

npm install piface

• Usage

var pfio = require("piface");

pfio.init();
var i = 0;
for (i = 0; i < 8; i++) {
    console.log("Pin #" + i + " = " + pfio.digital_read(0));
}

i = -1;
function anim() {
    i++;
    console.log("Pin #" + i + " on");
    pfio.digital_write(i, 1);
    if (i < 8) {
        setTimeout(function () {
            console.log("Pin #" + i + " off");
            pfio.digital_write(i, 0);
            if (i < 7) {
                anim();
            } else {
                pfio.deinit();
            }
        }, 250);
    }
}
anim();

• Methods

pfio.init();
pfio.deinit();
var val = pfio.digital_read(pin); // returns 0 or 1
pfio.digital_write(pin, val);
var val = pfio.read_input(); // returns 0..255
var val = pfio.read_output(pin, val); // returns 0..255
pfio.write_output(val);

• Interrupts

const piface = require("piface");

console.log("Initializing PiFace..");
piface.init();
console.log("Enabling interrupts..");
piface.enable_interrupts();
console.log("Ready. Waiting for input changes..");

const irFunc = () => {
  try {
    // wait for interrupt with infinite timeout
    const input = piface.wait_for_input(-1);
    console.log("Input:", input);

    // restart
    setTimeout(() => {
      irFunc();  
    }, 0);
  } catch (err) {
    console.error(err);
  }
};

// initially start waiting for interrupt
setTimeout(() => {
  irFunc();  
}, 0);