Electronics · nodejs · raspberry pi

Raspberry PI3 NodeJS GPIO Control: rpi-gpio

rp2_pinout

I’ve covered this in several other articles as a side effect of getting those higher level goals complete.  But given a simple Google Search failed me…  here is this in case someone else needs it.

When you just want: “Raspberry PI3 NodeJS GPIO Control” – this is how you get it done:

npm install --save rpi-gpio

Then the code.  Note the key piece for the Raspberry PI 3 is this:

gpio.setMode(gpio.MODE_BCM);

Blink NodeJS & rpi-gpio style:

Finally the whole code.  All this does is toggle pin 16. 🙂

var gpio = require('rpi-gpio');
gpio.setMode(gpio.MODE_BCM);

var lampPin = 16;
function pinBlink() {
 gpio.write(lampPin, false, (err) => {
   if (err) {
     console.log("Error in setting gpio pin.",err);
     return;
   }
 
   setTimeout(() => {
     gpio.write(lampPin, true, (err) => {
       if (err) {
         console.log("Error in setting gpio pin.",err);
         return;
       }
     });
   }, 1000);
 });
}

gpio.setup(lampPin, gpio.DIR_OUT, () => {
 setInterval(pinBlink, 2000);
});

Listening to a button state change (a.k.a. Button press)

Sometimes you just want to process a button press.  This is the code for that.  Note that you can change the transition you listen to with the last param:

var switchPin = 21;
gpio.setup(switchPin, gpio.DIR_IN, gpio.EDGE_FALLING);
gpio.on('change', function(channel, value) {
  //do something on the change.
});

Handy Pin Ref

rp2_pinout

Make sure you run as ROOT!

The GPIOs are worked with through the filesystem.  Your code can only reach those files if you run as root.

Channels/Pins you can’t use:

  • 1
  • 2
  • 4
  • 6
  • 9
  • 14
  • 17
  • 20
  • 25
  • 27
  • 28
  • 30
  • 34
  • 39

The above list is all reserved for something else… or ground, or 5V, or 3.3V… you get it. 🙂

Phew.

Now, hopefully, my future internet search friends will have a chance. 😉

2 thoughts on “Raspberry PI3 NodeJS GPIO Control: rpi-gpio

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