Connecting sensors to Mozilla’s IoT Gateway

Here is a 1st post about Mozilla’s IoT effort, and specifically the gateway project which is illustrating “Web Of Things” concept to create a decentralized Internet of Things, using Web technologies.

Today we will focus on the gateway, as it is the core component of the whole framework. Version 0.4.0 was just released, so you can try it your own on Raspberry Pi 3.  The Raspberry Pi 3 is the reference platform, but it should be possible to port to other single board computers (like ARTIK, etc).

The post will explain how to get started and how to establish basic automation using I2C sensors and actuators on gateway’s device (without any cloud connectivity).

To get started, first install the gateway according to these straightforward instructions:

Prepare SD Card

You need to download the Raspbian based (1GB archive) and dump it to SD card (2.6GB min).

lsblk # Identify your sdcard adapter ie:
wget -O- $url | funzip | sudo dd of=$disk bs=8M oflag=dsync

If you only want to use the gateway and not hack on it, you can skip this next part which enables a developer shell though SSH.  However, if you do want access to a developer shell, mount the 1st partition called “boot” (you may need to replug your SD card adapter) and add a file to enable SSH:

sudo touch /media/$USER/boot/ssh
sudo umount /media/$USER/*

First boot

Next, install the SD card in your Raspberry PI 3 (Older RPis could work too, particularly if you have a wifi adapter).

When it has completed the first boot, you can check that the Avahi daemon is registering “gateway.local” using mDNS (multicast DNS)

ping gateway.local
ssh pi@gateway.local # Raspbian default password for pi user is "raspberry"

Let’s also track local changes to /etc by installing etckeeper, and change the default password.

sudo apt-get install etckeeper
sudo passwd pi

Logging in

You should now be able to access the web server, which is running on port 8080 (earlier version used 80):


It will redirect you to a page to configure wifi:

URL: http://gateway.local:8080/
Connect to a WiFi network?

We can skip it for now:

URL: http://gateway.local:8080/connecting
WiFi setup skipped
The gateway is now being started. Navigate to gateway.local in your web browser while connected to same network as the gateway to continue setup.

After a short delay, the user should be able to reconnect to the entry page:


The gateway can be registered on for remote management, but we can skip this for now.

Then administrator is now welcome to register new users:

URL: http://gateway.local:8080/signup/
Mozilla IoT
Create your first user account:
user: user
email: user@localhost
password: password
password: password

And we’re ready to use it:

URL: http://gateway.local:8080/things
Mozilla IoT
No devices yet. Click + to scan for available devices.
Log out

Filling dashboard

You can start filling your dashboard with Virtual Resources,

First hit the “burger menu” icon, go to settings page, and then go to the addons page.

Here you can enable a “Virtual Things” adapter:

URL: http://gateway.local:8080/settings/addons/
virtual-things-adapter 0.1.4
Mozilla IoT Virtual Things Adapter
by Mozilla IoT

Once enabled It should be listed along ThingURLAdapter on the adapters page:

URL: http://gateway.local:8080/settings/adapters

You can then go back to the 1st Things page (it’s the first entry in the menu):

We can start adding “things” by pressing the bottom menu.

URL: http://gateway.local:8080/things
Virtual On/Off Color Light
Color Light

Then press “Done” at bottom.

From this point, you can decide to control a virtual lamp from the UI, and even establish some basic rules (second entry in menu) with more virtual resources.

Sensing Reality

Because IoT is not about virtual worlds, let’s see how to deal with the physical world using sensors and actuators.

For sensors, there are many way to connect them to computers using analog or digital inputs on different buses.  To make it easier for applications developers, this can be abstracted using W3C’s generic sensors API.

While working on IoT.js‘s modules, I made a “generic-sensors-lite” module that abstracted a couple of I2C drivers from the NPM repository.  To verify the concept, I have made an adapter for Mozilla’s IoT Gateway (which is running Node.js), so I published the generic-sensors-lite NPM module first.

Before using the mozilla-iot-generic-sensors-adapter, you need to enable the I2C bus on the gateway (version 0.4.0, master has I2C enabled by default).

sudo raspi-config
Raspberry Pi Software Configuration Tool (raspi-config)
5 Interfacing Options Configure connections to peripherals
P5 I2C Enable/Disable automatic loading of I2C kernel module
Would you like the ARM I2C interface to be enabled?
The ARM I2C interface is enabled
ls -l /dev/i2c-1
lsmod | grep i2c
i2c_dev 16384 0
i2c_bcm2835 16384 0

Of course you’ll need at least one real sensor attached to the I2C pin of the board.  Today only 2 modules are supported:

You can double check if addresses are present on I2C the bus:

sudo apt-get install i2c-tools
/usr/sbin/i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- 23 -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- 77

Install mozilla-iot-generic-sensors-adapter

Until sensors adapter is officially supported by the mozilla iot gateway, you’ll need to install it on the device (and rebuild dependencies on the target) using:

git clone --depth 1 -b 0.0.1 $url $dir
cd $dir
npm install

Restart gateway (or reboot)
sudo systemctl restart mozilla-iot-gateway.service
tail -F /home/pi/.mozilla-iot/log/run-app.log

Then the sensors addon can be enabled by pressing the “enable” button on the addons page:

URL: http://gateway.local:8080/settings/addons
generic-sensors-adapter 0.0.1
Generic Sensors for Mozilla IoT Gateway

It will appear on the adapters page too:

URL: https://gateway.local/settings/adapters

Now we can add those sensors as new things (Save and done buttons):

URL: http://gateway.local:8080/things
Ambient Light Sensor
Unknown device type
Temperature Sensor
Unknown device type

Then they will appear as:

  • http://gateway.local:8080/things/0 (for Ambient Light Sensor)
  • http://gateway.local:8080/things/1 (for Temperature Sensor)

To get value updated in the UI, they need to turned on first (try again if you find a big, and file tickets I will forward to drivers authors).

A GPIO adapter can be also used for actuators, as shown in this demo video.

If you have other sensors, check if the community has shared a JS driver, and please let me know about integrating new sensors drivers in generic-sensors-lite

IoT.js landed in Raspbian

Following previous efforts to deploy iotjs on Raspberry Pi 0, I am happy to announce that IoT.js 1.0 landed in Debian, and was sync’d to Raspbian for ArmHF and Ubuntu as well.

While the package is targeting the next distro release, it can be easily installed on current versions by adding a couple of config files for “APT pinning”.

If you haven’t set up Raspbian 9, just dump the current Raspbian image to SDcard (for the record I used version 2018-03-13-raspbian-stretch-lite)

Boot your Pi.  To keep track of changes in /etc/, let’s install etckeeper:

sudo apt-get update
sudo apt-get install etckeeper

Upgrade current packages:

sudo apt-get upgrade
sudo apt-get dist-upgrade

Declare the current release as default source:

cat<<EOT | sudo tee /etc/apt/apt.conf.d/50raspi
APT::Default-Release "stretch";

Then add a repo file for the next release:

cat /etc/apt/sources.list | sed 's/stretch/buster/g' | sudo tee /etc/apt/sources.list.d/raspi-buster.list

Unless you want to test the upcoming release, it maybe be safer to avoid upgrading all packages yet.  In other words, we prefer that only iotjs should be available from this “not yet supported” repo.

cat<<EOT | sudo tee /etc/apt/preferences.d/raspi-buster.pref
Package: *
Pin: release n=buster
Pin-Priority: -10

cat<<EOT | sudo tee /etc/apt/preferences.d/iotjs.pref
Package: iotjs
Pin: release n=buster
Pin-Priority: 1

Now iotjs 1.0-1 should appear as available for installation:

sudo apt-get update ; apt-cache search iotjs
iotjs - Javascript Framework for Internet of Things

apt-cache policy iotjs
  Installed: (none)
  Candidate: 1.0-1
  Version table:
     1.0-1 1
        -10 buster/main armhf Packages

Let’s install it:

sudo apt-get install iotjs
man iotjs

Even if version 1.0 is limited in compared to the development branch, you can start by using the http module which is enabled by default (not https).

To illustrate this, when I investigated “air quality monitoring” for a TizenRT+IoT.js demo I found out that OpenWeatherMap is collecting and publishing “Carbon Monoxide” Data, so let’s try their REST API.

Create a file, example.js for example, that contains:

var http = require('http');

var location = '48,-1';
var datetime = 'current';

//TODO: replace with your personal key
var api_key = 'fb3924bbb699b17137ab177df77c220c';

var options = {
  hostname: '',
  port: 80,
  path: '/pollution/v1/co/' + location + '/' + datetime + '.json?appid=' + api_key,

// workaround bug
options.headers = {
  host: options.hostname

http.request(options, function (res) {
  receive(res, function (data) {

function receive(incoming, callback) {
  var data = '';

  incoming.on('data', function (chunk) {
    data += chunk;

  incoming.on('end', function () {
    callback ? callback(data) : '';

And just run it:

iotjs example.js

You can then use this to do things such as update a map or raise an alert on anything useful, or try to rebuild master branch.

How to Run IoT.js on the Raspberry PI 0

IoT.js is a lightweight JavaScript platform for building Internet of Things devices; this article will show you how to run it on a few dollars worth of hardware. The First version of it was released last year for various platforms including Linux, Tizen, and NuttX (the base of Tizen:RT). The Raspberry Pi 2 is one of the reference targets, but for demo purposes we also tried to build for the Raspberry Pi Zero, which is the most limited and cheapest device of the family. The main difference is the CPU architecture, which is ARMv6 (like the Pi 1), while the Pi 2 is ARMv7, and the Pi 3 is ARMv8 (aka ARM64).

IoT.js upstream uses a python helper script to crossbuild for supported devices, but instead of adding support to new device I tried to build on the device using native tools with cmake and the default compiler options; it simply worked! While working on this, I decided to package iotjs for debian to see how well it will support other architectures (MIPS, PPC, etc), we will see.

Unfortunately, Debian armel isn’t optimized for ARMv6 and FPU, both of which are present on the Pi 1 and Pi 0, so the Raspbian project had to rebuild Debian for the ARMv6+VFP2 ARM variant to support all Raspberry Pi SBC’s.

In this article, I’ll share hints for running IoT.js on Raspbian: the OS officially supported by the Raspberry foundation; the following instructions will work on any Pi device since a portability strategy was preferred over optimization. I’ll demonstrate three separate ways to do this: from packages, by building on the device, and by building in a virtual machine. By the way, an alternative to consider is to rebuild Tizen Yocto for  the Pi 0, but I’ll leave that as an exercise for the reader, you can accomplish this with a bitbake recipe, or you can ask for more hints in the comments section.

How to Run IoT.js on the Raspberry PI 0 - tizen-pizero

Install from Packages

iotjs landed in Debian’s sid, and until it is in testing branch (and subsequently Raspbian and Ubuntu), the fastest way is to download it is via precompiled packages from my personal Raspbian repo

echo "deb $url raspbian main" | sudo tee "$source"
sudo apt-get update
apt-cache search iotjs
sudo apt-get install iotjs
Usage: iotjs [options] {script | script.js} [arguments]

Use it

Usage is pretty straightforward, start with a hello world source:

echo 'console.log("Hello IoT.js !");' > example.js
iotjs  example.js 
Hello IoT.js !

More details about the current environment can be used (this is for iotjs-1.0 with the default built-in modules):

echo 'console.log(JSON.stringify(process));' > example.js
iotjs  example.js 
{"env":{"HOME":"/home/user","IOTJS_PATH":"","IOTJS_ENV":""},"native_sources":{"assert":true,"buffer":true,"console":true,"constants":true,"dns":true,"events":true,"fs":true,"http":true,"http_client":true,"http_common":true,"http_incoming":true,"http_outgoing":true,"http_server":true,"iotjs":true,"module":true,"net":true,"stream":true,"stream_duplex":true,"stream_readable":true,"stream_writable":true,"testdriver":true,"timers":true,"util":true},"platform":"linux","arch":"arm","iotjs":{"board":"\"unknown\""},"argv":["iotjs","example.js"],"_events":{},"exitCode":0,"_exiting":false} null 2

From here, you can look to use other built-in modules like http, fs, net, timer, etc.

Need More Features?

More modules can be enabled in the master branch, so I also built snapshot packages that can be installed to enable more key features like GPIO, I2C, and more. For your convenience, the snapshot package can be installed to replace the latest release:

root@raspberrypi:/home/user$ apt-get remove iotjs iotjs-dev iotjs-dbgsym iotjs-snapshot
root@raspberrypi:/home/user$ aptitude install iotjs-snapshot
The following NEW packages will be installed:
The following packages have unmet dependencies:
 iotjs-snapshot : Depends: iotjs (= 0.0~1.0+373+gda75913-0~rzr1) but it is not going to be installed
The following actions will resolve these dependencies:
     Keep the following packages at their current version:
1)     iotjs-snapshot [Not Installed]                     
Accept this solution? [Y/n/q/?] n
The following actions will resolve these dependencies:

     Install the following packages:                 
1)     iotjs [0.0~1.0+373+gda75913-0~rzr1 (raspbian)]
Accept this solution? [Y/n/q/?] y
The following NEW packages will be installed:
  iotjs{a} iotjs-snapshot 
Do you want to continue? [Y/n/?] y

Do you want to ignore this warning and proceed anyway?
To continue, enter "yes"; to abort, enter "no": yes
Get: 1 raspbian/main armhf iotjs armhf 0.0~1.0+373+gda75913-0~rzr1 [199 kB]
Get: 2 raspbian/main armhf iotjs-snapshot armhf 0.0~1.0+373+gda75913-0~rzr1 [4344 B]

If you the run console.log(process) again, you’ll see more interesting modules to use, like gpio, i2c, uart and more, and external modules can be also used; check on the work in progress for sharing modules to the IoT.js community. Of course, this can be reverted to the latest release by simply installing the iotjs package because it has higher priority than the snapshot version.

root@raspberrypi:/home/user$ apt-get install iotjs
The following packages will be REMOVED:
The following packages will be upgraded:
Do you want to continue? [Y/n] y

Build on the Device

It’s also possible to build the snapshot package from source with extra packaging patches, found in the community branch of IoT.js (which can be rebased on upstream anytime).

sudo apt-get install git time sudo
git clone
cd iotjs
sudo debi

On the Pi 0, it took less than 30 minutes over NFS for this to finish. If you want to learn more you can follow similar instructions for building IoTivity on ARTIK;
it might be slower, but it will extend life span of your SD Cards.

Build on a Virtual Machine

A faster alternative that’s somewhere between building on the device and setting up a cross build environment (which always has a risk of inconsistencies) is to rebuild IoT.js with QEMU, Docker, and binfmt.

First install docker (I used 17.05.0-ce and 1.13.1-0ubuntu6), then install the remaining tools:

sudo apt-get install qemu qemu-user-static binfmt-support time
sudo update-binfmts --enable qemu-arm

docker build ''

It’s much faster this way, and took me less than five minutes. The files are inside the container, so they need to be copied back to host. I made a helper script for setup and to get the deb packages ready to be deployed on the device (sudo dpkg -i *.deb) :

curl -sL | bash -x -

I used the Resin/rpi-raspbian docker image (thanks again Resin!). Finally, I want to also thank my coworker Stefan Schmidt for the idea after he setup a similar trick for EFL’s CI.

Further Reading

If you want to learn more, here are some additional resources to take your understanding further.

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