Tutorial: Alexa with Indoor Air Quality

In this tutorial we show you how to set-up an Amazon Alexa smart speaker based on a Raspberry Pi 3 that you can ask for the current indoor air quality, ambient temperature and humidity.

Prerequisites

Software

AWS Account and AWS developer account
A computer with SSH setup (Ubuntu LTS is recommended)
Basic Linux and Raspberry Pi know-how is of Advantage
Here you can download the sample codes for smart speaker resources: smart_speaker_resources.tar.gz

Hardware Components

Raspberry Pi 3
ReSpeaker 2-Mics Pi HAT
SHTC1 and SGPC3 connected to i2c-1 (e.g. as a Raspberry Pi Shield)
A speaker up to 1 Watt (we use a 0.5 Watt speaker)
JST 2.0 Micro cable to connect the speaker to the Re-Speaker
Optional: a couple of spacers and screws and a plexiglas cover

Hardware Assembly

Note that for the rest of the tutorial, we'll be using Sensirion's Environmental Sensor Shield; if you're using your own sensor Hardware, please make sure you connect them in the same way, connecting to I²C-1.

Step 1

Install 2 x 12 mm² female-female spacers to the site with the shield connector of the Raspberry Pi 3 and 2 x 12 mm² male-female spacers to the opposite site.

Step 2

Add 2 x 10 mm² female-female spacers to the middle holes of sensor shield as shown in the picture below.

Step 3

Plug the sensor shield onto the Raspberry Pi 3 and screw it down.

Step 4

Install 2 x 10 mm² female-female spacers to the Respeaker-2 mic HAT. You can skip this step if you don’t have a plexiglass cover.

Step 5

Plug the ReSpeaker board onto the sensor board and screw down. If you have a plexi glass cover, you can also stack the 10 mm male-female and 12mm female-female spacer and add them as pictured below.

Step 6

Cut the JST 2.0 to the appropriate length and solder it to the speaker.

Step 7

Glue the Speaker on the plexiglass cover, and install the cover on top. Afterwards you can plug in the JST 2.0 cable.

Software Setup

Step 1: Prepare your host system

All instructions assume you are running an Ubuntu or other Debian-like operating system. For other operating systems, please refer to official documentation here.

sudo apt-get install zip pv

Step 2: Setup Raspberry PI

Download the latest raspbian stretch light image from the official Homepage: www.raspberrypi.org/downloads/raspbian/
Unzip and install it on your SD-Card. Make sure the output device points to your SD card.

unzip 2017-11-29-raspbian-stretch-lite.zip
pv 2017-11-29-raspbian-stretch-lite.img | sudo dd of=/dev/mmcblk0 oflag=sync bs=4M

Setup SSH connection:

You need to connect a keyboard and display to the Raspberry Pi for the initial setup.

Enable SSH

sudo systemctl enable ssh
sudo systemctl start ssh

Setup DHCP on eth0 and disable dhcpcd service (we will setup our own configuration with dnsmasq)

sudo systemctl disable dhcpcd.service

create directory for dnsmasq

mkdir -p /etc/dnsmasq.d/

And setup own dhcpd service: Create a file /etc/dnsmasq.d/dhcp with the following content

# DHCP only on eth0
interface=eth0
dhcp-range=eth0,192.168.1.100,192.168.1.199,4h

# disable sending DNS server and router
dhcp-option=3
dhcp-option=6

Setup Network connection:

Create a file /etc/wpa_supplicant/wpa_supplicant.conf with the following content:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
        ssid="<my-wifi-name>"
        scan_ssid=1
        proto=RSN
        key_mgmt=WPA-PSK
        pairwise=CCMP TKIP
        group=CCMP TKIP
        psk="<my-wifi-password>"
}

Replace <my-wifi-name> and <my-wifi-password> with the SSID and password of your wifi.

Edit /etc/network/interfaces and replace everything in there with the following content

auto lo
auto wlan0
auto eth0

iface lo inet loopback
iface default inet dhcp

allow-hotplug eth0
iface eth0 inet static
    address 192.168.1.10
    netmask 255.255.255.0
    network 192.168.1.0
    broadcast 192.168.1.255

allow-hotplug wlan0
iface wlan0 inet dhcp
    pre-up wpa_supplicant -Dwext -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf -B
    pre-down killall wpa_supplicant

Now you can restart and finalize networking

sudo systemctl restart networking.service
sudo apt install dnsmasq

Setup SSH connection

From your host you can now setup the SSH connection for easy access

ssh-copy-id pi@192.168.1.10

From now on you can ssh into the Raspberry Pi with ssh pi@192.168.1.10

Setup I²C and SPI

We use raspi-config to enable i2c and spi for the Raspberry Pi. The options are under 4 Interfacing Options

sudo raspi-config

Note: You can also expand the file system if you like, so you can use the whole space of the SD-card. Allow the user to access the spi and i2c interfaces by configuring two udev rules:

sudo addgroup i2c
sudo addgroup spi

/etc/udev/80-i2c.rules

KERNEL=="i2c-dev", GROUP="i2c", MODE="0660"
# set I2C permissions for regular I2C drivers
SUBSYSTEM=="i2c", RUN+="/bin/chgrp -R i2c /sys%p", RUN+="/bin/chmod -R g=u /sys%p"
# set I2C permissions for input-type I2C drivers
SUBSYSTEM=="input", RUN+="/bin/chgrp -R i2c /sys%p", RUN+="/bin/chmod -R g=u /sys%p"

/etc/udev/81-spi.rules

KERNEL=="spidev*", GROUP="spi", MODE="0660"

And in /boot/config.txt add the following: /boot/config.txt

dtparam=i2c0=on
dtparam=i2c1=on
dtparam=i2c_arm=on
dtparam=i2c_vc=on
dtparam=i2c0_baudrate=40000
dtparam=i2c1_baudrate=40000

and in /etc/modules

i2c-bcm2708

shtc1
sgpxx

Now install some tools we need on the Raspberry Pi (make sure the wifi connection from on the Raspberry Pi works)

sudo apt-get install build-essential raspberrypi-kernel-headers git python-pip i2c-tools 
sudo pip install virtualenv spidev

Setup the sgpc3 driver

Copy the driver source to the raspberry pi

scp sgpxx.tar.gz pi@192.168.1.10:

Unpack it and compile it

Install SGPC3 driver and crc8 dependency

mkdir -p src/sgpxx
tar -xzf sgpxx.tar.gz -C src/sgpxx

# Install CRC8 module
cd src
git clone https://github.com/Sensirion/crc8.git
cd crc8
make
sudo install -p -m 644 crc8.ko /lib/modules/$(uname -r)/kernel/drivers/
sudo depmod -a
sudo modprobe crc8

# Install SGPxx driver
cd ~/src/sgpxx/
make
sudo install -p -m 644 sgpxx.ko /lib/modules/$(uname -r)/kernel/drivers/iio/
sudo depmod -a
sudo modprobe sgpxx

Reboot the Raspberry Pi

sudo reboot

Step 3: Install AlexaPi

We are using AlexaPi project to setup the connection to Alexa. Before installing Alexa Pi you have to setup an Alexa Voice Service. You can follow the instructions (only 1. Register at Amazon) on this page: github.com/alexa-pi/AlexaPi/wiki/Installation

Make sure you also add 192.168.1.10:5050 as an allowed endpoint for the registration, so you can register the alexa device from your host computer.

There are also plenty of other resources available online on how to register a device. Make sure you write down all the credentials, you will need them in this step.

Execute the following steps on the Raspberry Pi to install AlexaPi:

sudo su
cd /opt
git clone https://github.com/alexa-pi/AlexaPi.git 
/opt/AlexaPi/src/scripts/setup.sh

You will be asked for some information.

For the first few questions you can just click enter, the defaults are fine:

OS: debian
Your device: raspberrypi
Do you want AlexaPi to run on boot? 1 - yes systemd
Would you like to also install Airplay support? Yes (or no, it does not matter)

When you are asked for the client setup:

Enter your Device Type ID []:
Enter your Security Profile Description []:
Enter your Security Profile ID []:
Enter your Client ID []:
Enter your Client Secret []:

After AlexaPi is finished with the installation you have to open 192.168.1.10 on your host computer which will forward you to the AWS login. Login with your amazon account and the alexa device will be connected to your user. You should now also be able to find and configure the device under alexa.amazon.com

Patch AlexaPi

Copy the following 2 files to /opt/AlexaPi/src/alexapi/device_platforms/

ap102.py
respeaker2micplatform.py

Update /etc/opt/AlexaPi/config.yaml and change the device to "respeaker2mic" and add the respeaker2mic config to platforms:

platform:
  device: "respeaker2mic"

platforms:
  respeaker2mic:
    # GPIO Pin with button connected
    button: 17

Setup SPI and GPIO access

sudo adduser alexapi spi
sudo adduser pi gpio
sudo adduser pi i2c

(optional) Audio debugging for root and pi user

sudo adduser root audio
sudo adduser pi audio

Load SHTC1 and SGPC3 on startup. Add the following to /etc/rc.local

echo sgpc1x 0x58 | sudo tee /sys/class/i2c-adapter/i2c-1/new_device
echo shtc1 0x70 | sudo tee /sys/class/i2c-adapter/i2c-1/new_device

udevadm trigger

Step 5: Setup ReSpeaker 2 mic head

On the raspberry pi

sudo su
cd /opt
git clone https://github.com/respeaker/seeed-voicecard.git
cd seeed-voicecard
sudo ./install.sh 2mic

Step 6: Restart Raspberry Pi

Restart your Raspberry Pi

sudo reboot

Step 7: Configure Alsa

Use alsamixer to set the microphones and speaker levels

Recommended settings (press F4 to get to playback settings):

Step 8: Setup IAQ Logger

We are using the Sensirion cloud to upload the logged data. If you want to use a different backend like AWS IoT please adapt the code accordingly or use a different logger.

On the Raspberry Pi create a folder for the IAQ logger

sudo mkdir ~/iaq_logger

Copy the iaq logger code onto the Raspberry Pi into the newly created folder

scp iaq_logger_app.tar.gz  pi@192.168.1.10:iaq_logger/

On the Raspberry Pi

cd iaq_logger
tar -xzf iaq_logger_app.tar.gz

And run setup.sh (as pi user)

./setup.sh

Setup Indoor Air Quality Skill

To use the indoor air quality feature we have to implement a custom skill and connect it to AWS lambda. A full documentation on how to configure such a skill can be found on the amazon developer page:

https://developer.amazon.com/docs/custom-skills/host-a-custom-skill-as-an-aws-lambda-function.html

You can choose the alexa-skills-kit-color-expert-python and replace the code with the on provided in the package.

On the developer.amazon.com you can now configure a new Alexa skill. For our smart speaker we used to following interaction model.

Setup Indoor Air Quality Skill

{
  "languageModel": {
    "intents": [
      {
        "name": "AirQuality",
        "samples": [
          "tell me air quality",
          "tell me indoor air quality"
        ],
        "slots": []
      },
      {
        "name": "AMAZON.CancelIntent",
        "samples": []
      },
      {
        "name": "AMAZON.HelpIntent",
        "samples": []
      },
      {
        "name": "AMAZON.StopIntent",
        "samples": []
      },
      {
        "name": "Humidity",
        "samples": [
          "tell me humidity",
          "tell me ambient humidity"
        ],
        "slots": []
      },
      {
        "name": "Temperature",
        "samples": [
          "tell me temperature",
          "tell me ambient temperature"
        ],
        "slots": []
      }
    ],
    "invocationName": "sensirion"
  }
}

Congrats, you've made it! Try asking Alexa the following "Alexa, ask Sensirion what's the temperature?".

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Tutorial: Alexa with Indoor Air Quality

Prerequisites

Software

Hardware Components

Hardware Assembly

Step 1

Step 2

Step 3

Step 4

Step 5

Step 6

Step 7

Software Setup

Step 1: Prepare your host system

Step 2: Setup Raspberry PI

Enable SSH

Setup DHCP on eth0 and disable dhcpcd service (we will setup our own configuration with dnsmasq)

create directory for dnsmasq

And setup own dhcpd service: Create a file /etc/dnsmasq.d/dhcp with the following content

Edit /etc/network/interfaces and replace everything in there with the following content

Now you can restart and finalize networking

From your host you can now setup the SSH connection for easy access

We use raspi-config to enable i2c and spi for the Raspberry Pi. The options are under 4 Interfacing Options

Note: You can also expand the file system if you like, so you can use the whole space of the SD-card. Allow the user to access the spi and i2c interfaces by configuring two udev rules:

/etc/udev/80-i2c.rules

/etc/udev/81-spi.rules

And in /boot/config.txt add the following: /boot/config.txt

and in /etc/modules

Now install some tools we need on the Raspberry Pi (make sure the wifi connection from on the Raspberry Pi works)

Copy the driver source to the raspberry pi

Install SGPC3 driver and crc8 dependency

Step 3: Install AlexaPi

Execute the following steps on the Raspberry Pi to install AlexaPi:

When you are asked for the client setup:

Update /etc/opt/AlexaPi/config.yaml and change the device to "respeaker2mic" and add the respeaker2mic config to platforms:

Setup SPI and GPIO access

(optional) Audio debugging for root and pi user

Load SHTC1 and SGPC3 on startup. Add the following to /etc/rc.local

On the raspberry pi

Restart your Raspberry Pi

Step 8: Setup IAQ Logger

On the Raspberry Pi create a folder for the IAQ logger

Copy the iaq logger code onto the Raspberry Pi into the newly created folder

On the Raspberry Pi

And run setup.sh (as pi user)

Setup Indoor Air Quality Skill

Setup Indoor Air Quality Skill

Related Sensors

Digital Humidity Sensor SHTC1 (RH/T)

Multi-Pixel Gas Sensors SGP

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