This is using a web service running on Heroku instead of AWS Lambda adapter. It makes the adapter code much more flexible.

1. Voice controlled Home
Automation
Using Amazon Alexa and PubNub

2. This is the basic hardware
setup. Raspberry Pi 3 with a
USB Microphone, speakers.
HDMI connection,
keyboard/mouse are not
shown for simplicity.
A beaglebone black with an
LED connected on a GPIO.
Both boards connected to
Internet.
Internet
Internet

3. We also need accounts on
Amazon developer, Heroku
and PubNub.
Amazon hosts Alexa voice
service and our skill.
Heroku hosts our skill
adapter code.
PubNub is used for message
passing from skill adapter to
beaglebone.
Skill adapter code
as web service
Publish /
Subscribe
architecture
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)

4. Subscribed to PubNub
channel ‘alexa_world’
Skill adapter code
as web service
Publish /
Subscribe
architecture
Running Alexa app
with wakeword agent
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)
Run the Alexa app on
Raspberry Pi.
Run the PubNub subscribing
and GPIO controller code on
beaglebone.

5. Alexa app is continuously
listening for the keyword
‘Alexa’. When user speaks
the keyword, the app listens
to the voice until a pause. In
this case it is the sentence
‘Alexa, ask my home to turn
on bedroom light’.
•Alexa voice service
•Alexa Skill (‘My home’)
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet

6. Alexa app sends the audio to
Alexa voice service running
in Amazon cloud
(developer.amazon.com)
along with device
authentication details and
other metadata.
Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)

7. In this case, the intent is
to ‘turn on’ something and
the slot is ‘bedroom light’.
This data is then passed on
to Heroku web service
endpoint running skill
adapter code.
Alexa voice service
interprets the voice and
determines that this is a
request for the skill ‘My
home’. It then further
decodes the voice data and
parses it into an intent
(action to be done)
and slot (object to be
acted upon).
Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Parsed data to Skill adapter
Intent: “Turn on”
Slot: “Bedroom light”
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)

8. Skill adapter code processes
the intent and publishes a
message to PubNub network
on channel named
‘alexa_world’. This message
contains command as
‘TURN_ON’ and gadget as
‘bedroom light’.
Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Parsed data to Skill adapter
Intent: “Turn on”
Slot: “Bedroom light”
Publish message to
channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)

9. Skill adapter also sends an
ACK to voice service which is
passed back to the alexa app
running on pi. This can
contain a voice feedback
such as “Ok”
Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Parsed data to Skill adapter
Intent: “Turn on”
Slot: “Bedroom light”
Publish message to
channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)
“Ok”
(Voice
feedback)
ACK from
skill adapter
(with voice
feedback)

10. PubNub network sends out
the same message to all
devices subscribed to
channel ‘alexa_world’. In this
case, the beaglebone is
subscribed to this channel
and hence receives the
message.
Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Parsed data to Skill adapter
Intent: “Turn on”
Slot: “Bedroom light”
Publish message to
channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Send message to subscribers
of channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)
ACK from
skill adapter
(with voice
feedback)

11. Audio
Skill adapter code
as web service
Publish /
Subscribe
architecture
Alexa, ask
My Home
to turn on
bedroom
light
Parsed data to Skill adapter
Intent: “Turn on”
Slot: “Bedroom light”
Publish message to
channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Send message to subscribers
of channel ‘alexa_world’:
Command: “TURN_ON”
Gadget: “bedroom light”
Running Alexa app
with wakeword agent
Subscribed to PubNub
channel ‘alexa_world’
Internet
Internet
•Alexa voice service
•Alexa Skill (‘My home’)
Beaglebone then processes
received message and turns
on the GPIO corresponding
to ‘bedroom light’.
ACK from
skill adapter
(with voice
feedback)