Raspberry Pi

(the previous version of these instructions can be found here.)

Installation

The simplest way to install node.js on Pi is

wget http://node-arm.herokuapp.com/node_latest_armhf.deb
sudo dpkg -i node_latest_armhf.deb

Then after following the instructions to install Node-RED, make sure the Python RPi.GPIO libraries are installed…

$sudo apt-get install python-dev python-rpi.gpio

Change Using RPi.GPIO is a change from using WiringPi - the main benefits are that we can get software PWM on all output pins, and easier access to interrupts on inputs meaning faster response times (rather than polling).

NOTE - The Garbage Collector (GC) algorithm in node.js v0.10.x behaves differently than v0.8.x - in that it doesn’t enforce a clean until it is near a memory limit larger than the 512MB in the Pi - this can cause the Pi to crash if left running for a long time, so we recommend starting Node-RED like this

$ cd node-red
$ node --max-old-space-size=128 red.js

This extra parameter limits the space it can use to 128MB before cleaning up. If you are running nothing else on your Pi feel free to up that to 192 or 256… the command free -h will give you some clues if you wish to tweak.

Once you restart Node-RED and then browse to http://{your-pi-address}:1880 you should now see two rpi-gpio nodes in the advanced section of the pallette. One to read from pins, and one to control pins. If they are not there then check both the nrgpio and nrgpio.py commands installed correctly to the ~/node-red/nodes/core/hardware/ directory and are executable by the user that you are running as. To check:

$ ~/node-red/nodes/core/hardware/nrgpio ver 0

should return… 0.5.8 or greater - this is the version of the RPi.GPIO library.

NOTE: the old Midori browser does not have adequate javascript support to use it with Node-RED. If you want to use a built in browser on the Pi please install the Epiphany browser and use that pointed at http://localhost:1880. Epiphany is now the default Rasbian browser, or you can install it by

$ sudo apt-get install epiphany-browser

There are also some extra hardware specific nodes (for the Pibrella, PiFace and LEDBorg plug on modules) available in the node-red-nodes project on Github.

There are (at least) two ways for interacting with a Raspberry Pi using Node-RED.

rpi-gpio nodes
provided in the palette for monitoring and controlling the GPIO pins. This is the simplest and recommended way.
wiring-pi module
this provides complete access to the GPIO pins, and other devices, within Function nodes. This gives more control and access to other features not in the nodes but you have to program it yourself.

rpi-gpio nodes

These use a python nrgpio command as part of the core install and can be found in node-red/nodes/core/hardware

This provides a way of controlling the GPIO pins via nodes in the Node-RED palette.

The nrgpio command MUST be executable by the user that is running Node-RED. That user MUST have root access to run python in order to access the pins directly. The default user Pi does have this access and is the recommended user with which to run Node-RED.

If you want to run as a different user you will need either to add that user to the sudoers list - or maybe just access to python - for example by adding the following to sudoers using visudo.

NodeREDusername ALL=(ALL) NOPASSWD: /user/bin/python

To run a “blink” flow that toggles an LED on Pin 11 of the GPIO header, you will need to connect up an LED as described here.

Then copy the following flow and paste it into the Import Nodes dialog (Import From - Clipboard in the dropdown menu, or Ctrl-I). After clicking okay, click in the workspace to place the new nodes.

    [{"id":"ae05f870.3bfc2","type":"function","name":"Toggle 0/1 on input","func":"\ncontext.state = context.state || 0;\n\n(context.state == 0) ? context.state = 1 : context.state = 0;\nmsg.payload = context.state;\n\nreturn msg;","outputs":1,"x":348.1666488647461,"y":146.16667652130127,"wires":[["1b0b73e9.14712c","b90e5005.a7c3b8"]]},{"id":"1b0b73e9.14712c","type":"debug","name":"","active":true,"x":587.1666488647461,"y":206.1666774749756,"wires":[]},{"id":"7aa75c69.fd5894","type":"inject","name":"tick every 1 sec","topic":"","payload":"","repeat":"1","crontab":"","once":false,"x":147.1666488647461,"y":146.1666774749756,"wires":[["ae05f870.3bfc2"]]},{"id":"b90e5005.a7c3b8","type":"rpi-gpio out","name":"","pin":"7","x":585.0000114440918,"y":146.00001049041748,"wires":[]}]

Click the deploy button and the flow should start running. The LED should start toggling on and off once a second.


wiring-pi module

This version of working with the Raspberry Pi uses a node.js wrapper to the WiringPi libraries previously installed, and so gives all functions you write access to the Pi capabilities at all times, so you can do more complex things, at the expense of having to write code within a function rather than dragging and wiring nodes.

Installation

After installing Node-RED, follow these instructions to get Wiring Pi installed.

Configuring Node-RED

Firstly the npm module needs to be installed into the node-red directory.

cd ~/node-red-x.y.z    (changing x.y.z to match the version you have installed)
npm install wiring-pi

This does not add any specific nodes to Node-RED. Instead the Wiring-Pi module can be made available for use in Function nodes.

To do this, update settings.js to add the wiring-pi module to the Function global context:

functionGlobalContext: {
    wpi: require('wiring-pi')
}

The module is then available to any functions you write as context.global.wpi.

To run a “blink” flow that uses the WiringPi pin 0 - Pin 11 on the GPIO header, you will need to connect up an LED as described here.

Then copy the following flow and paste it into the Import Nodes dialog (Import From - Clipboard in the dropdown menu, or Ctrl-I). After clicking okay, click in the workspace to place the new nodes.

[{"id":"860e0da9.98757","type":"function","name":"Toggle LED on input","func":"\n// select wpi pin 0 = pin 11 on header (for v2)\nvar pin = 0;\n\n// initialise the wpi to use the global context\nvar wpi = context.global.wpi;\n\n// use the default WiringPi pin number scheme...\nwpi.setup();\n\n// initialise the state of the pin if not already set\n// anything in context.  persists from one call to the function to the next\ncontext.state = context.state || wpi.LOW;\n\n// set the mode to output (just in case)\nwpi.pinMode(pin, wpi.modes.OUTPUT);\n\n// toggle the stored state of the pin\n(context.state == wpi.LOW) ? context.state = wpi.HIGH : context.state = wpi.LOW;\n\n// output the state to the pin\nwpi.digitalWrite(pin, context.state);\n\n// we don't \"need\" to return anything here but may help for debug\nreturn msg;","outputs":1,"x":333.16666412353516,"y":79.16666793823242,"wires":[["574f5131.36d0f8"]]},{"id":"14446ead.5aa501","type":"inject","name":"tick","topic":"","payload":"","repeat":"1","once":false,"x":113.16666412353516,"y":59.16666793823242,"wires":[["860e0da9.98757"]]},{"id":"574f5131.36d0f8","type":"debug","name":"","active":true,"x":553.1666641235352,"y":99.16666793823242,"wires":[]}]

Click the Deploy button and the flow should start running. The LED should start toggling on and off once a second.


Making Node-RED autostart on boot (optional)

To make Node-RED into a service by using init.d - thanks to our contributors for this. Init.d script

Copy the init.d script into /etc/init.d/node-red and make it executable. You can then stop, start and restart Node-RED by

$ sudo service node-red stop
$ sudo service node-red start
$ sudo service node-red restart

If you need Node-RED to autostart on boot then use this command

$ sudo update-rc.d node-red defaults

Once running you should then be able to attach to the screen session to see the console by running:

$ sudo screen -r red

To detach from the session and leave it running, type Ctrl-A-D.

And alternative is to use screen so you can get to the console at any time. To install screen, if it is not already there, run:

$ sudo apt-get install screen

then use a script like this Node-RED init script