8ea007141a4d5107c9ed6d0ec40749a5_original

Tutorial: Voice Time! SmartPlantPi, Raspberry Pi and Amazon Alexa

We are pleased to announce Version 018 of the SmartPlantPi Raspberry Pi Python based software and the big change is that we now support the Amazon Alexa, Echo, Echo Plus, and all other Amazon Voice systems. In this tutorials we will show you how to connect up the Alexa systems in your house to your SmartPlantPi. We will be rolling this really cool feature set into our other major kit offerings including:

This is an instructional tutorial to get your SmartPlantPi to Amazon Alexa Interface working. All source code is provided!

While we are focusing on SmartPlantPi in this tutorial the techniques we developed are good for many projects.

This tutorial assumes you have set up PubNub for the SmartPlantPi Internet Dashboard. Before you continue with this tutorial, please do the setup as shown in the SmartPlantPi Advanced Products Manual and update to at least Version 019+ for SmartPlantPi here on GitHub.

What is SmartPlantPi?

SmartPlantPi (or Smart Plant for short) is an introductory, easy to build Raspberry Pi based environmental monitoring and plant watering system using advanced sensors to monitor the soil moisture, monitor the sunlight, watch the air quality and monitor temperature and humidity.

[callout size=”col-12″ title=”SmartPlantPi now in SwitchDoc Labs Store” button_title=”SmartPlantPi” button_link=”https://shop.switchdoc.com/products/smartplantpi-raspberry-pi-based-smart-plant-kit-no-soldering” button_size=”normal” button_rounded=”true” button_color=”red”]

See the Grove Connector Tutorial Here.

How does the SmartPlantPi to Alexa Interface Work?

Below is a block diagram of how the system works to get SmartPlantPi Information up to Alexa and how to respond to voice commands with real information.

The Alexa Voice to SmartPlantPi Project

There are four major parts to this project.

– PubNub – MQTT Broker between SmartPlantPi and the AWS Lambda function
– The Alexa Skill – Controls Alexa on Echos in your house
– The AWS Lambda Serverless Function for brokering information from PubNub to the Alexa Skill
– SmartPlantPi – MQTT Publisher SmartPlantPi Information to PubNub

What is MQTT?

Since the main transport protocol used in this project is MQTT, an explanation is in order.

MQTT is a publish-subscribe based “light weight” messaging protocol for use on top of the TCP/IP protocol, such as the WiFi packets that we are using in this project. It is designed for connections with remote locations where a “small code footprint” is required or the network bandwidth is limited. The publish-subscribe messaging pattern requires a message broker. The broker (PubNub in this case) is responsible for distributing messages to interested clients based on the topic of a message.

Publish–subscribe is a pattern where senders of messages, called publishers (in this case our ESP8266 is the publisher), don’t program the messages to be sent directly to subscribers, but instead characterize message payloads into classes without the specific knowledge of which subscribers the messages are sent to. Similarly, subscribers will only receive messages that are of interest without specific knowledge of which publishers there are. Mosquitto operates as the broker in this system and routes the published data to the appropriate subscribers.

You can think of MQTT as writing stories for a newspaper where you don’t know who will be subscribing to the article.

What is JSON?

JSON is an open standard format that uses human-readable text to transmit data objects consisting of attribute–value pairs. It is the primary data format used for asynchronous browser/server communication, largely replacing XML. XML is a “heavier” protocol that is also hierarchical in nature, but with a great deal more redundancy that JSON. Yes, there are class wars going on for people that advocate JSON over XML, but in todays world of higher speed communication, it rarely matters. You can make the argument that the higher data density of JSON is a better choice for IOT applications.

The Four Blocks of the Alexa Voice to SmartPlantPi Project

PubNub

PubNub is an MQTT broker in the same sense as Mosquitto MQTT Broker is on a Raspberry Pi Platform.

PubNub is a global Data Stream Network (DSN) and realtime infrastructure-as-a-service (IaaS) company based in San Francisco, California. The company makes products for software and hardware developers to build realtime web, mobile, and Internet of Things(IoT) applications.

PubNub’s primary product is a realtime MQTT publish/subscribe[2] messaging API built on their global data stream network which is made up of a replicated network of at least 14 data centers located in North America, South America, Europe, and Asia. The network currently serves over 300 million devices and streams more than 750 billion messages per month.

The foundation of PubNub is providing you the ability to integrate scalable, realtime data streams into your applications. Using the publish/subscribe paradigm, subscribers to a particular channel will receive any and all messages that are published to that channel. It doesn’t matter if there is one subscriber, 10 subscribers, 1000 subscribers or millions of subscribers, a published message will be delivered to all of those subscribers on that channel in less than ¼ second.

PubNub also supports BLOCKS micro services which can act like AWS Lambda Severless functions. More on BLOCKS in future blog postings.

As in the block diagram above, data from SmartPlantPi is sent via MQTT to PubNub. PubNub stores a short history of messages (the last one will be grabbed by the AWS Lambda function below) as a topic (OWIOT1 is the channel in this case).

The basic level of PubNub (which we are using) is free.

The Alexa Skill

Alexa is Amazon’s voice service and the brain behind tens of millions of devices like the Amazon Echo, Echo Dot, and Echo Show. Alexa provides capabilities, or skills, that enable customers to create a more personalized experience. There are now tens of thousands of skills from companies like Starbucks, Uber, and Capital One as well as other innovative designers and developers.

We are building an Alexa skill that will interface to the SmartPlantPi from Switchdoc Labs. It provides the interface from your Amazon echo to the SmartPlantPi system. The Alexa skill manages the voice part of the project. It takes verbal commands (“Alexa, ask Smart Plant Status” which gives the current status on YOUR SmartPlantPi. It is important to note that you will never publish your skill to the general market. This is for all your Amazon Echos, etc. at your house wired to your Amazon account. At our CTOs house, he has about 10 Alexa devices all wired into his Amazon account and wired into his various SwitchDoc projects, such as OurWeather and GroveWeatherPi.

An Amazon Alexa skill takes voice input from an Amazon Echo or other device, translates it to text, compares it agains what the skill is expecting (“utterances”) and then sends a JSON response to a specific application or server (we have used Apache servers in the past to receive this input, but this requires you to poke a hole in your home firewall and was really too complex for the normal user to implement). This lead to our use of the “event driven” AWS Lambda function. No server. No firewall problems. No software server on your site. Much simpler.

The Alexa Skills Kit (ASK) is a collection of self-service APIs, tools, documentation, and code samples that makes it fast and easy for you to add skills to Alexa. ASK enables designers, developers, and brands to build engaging skills and reach customers through tens of millions of Alexa-enabled devices. With ASK, you can leverage Amazon’s knowledge and pioneering work in the field of voice design.

In Part 2 we will show you how to set up your Alexa Skill to interface to SmartPlantPi.

We kid you not. This is a cool set of tools and an interesting process.

This is another free account with Amazon.

The AWS Lambda Serverless Function

The Lambda function is the most difficult to understand part of this project. Why do we need this? An Amazon Alexa Skill is concerned with “utterances” and how to interpret them. When you talk to Alexa, Alexa translates your speech to text, sends a request to the Lambda function. The Lambda function interprets this Alexa JSON request, gathers the SmartPlantPi data via an MQTT history request from PubNub (which came from SmartPlantPi via MQTT), and sends a text response (JSON again) to Alexa with the required plant data embedded, and Alexa speaks the result.

AWS Lambda is an event-driven, serverless computing platform provided by Amazon as a part of the Amazon Web Services. It is a compute service that runs code in response to events and automatically manages the compute resources required by that code. It was introduced in 2014.

We are using node.js to write our Lambda Function. Parts were very challenging (dealing with asynchronous callbacks in a environment that will terminate when you are done running code), but we got it to work perfectly. You will find the open source code in Part 3.

The purpose of Lambda, as compared to AWS EC2 (cloud based servers), is to simplify building smaller, on-demand applications that are responsive to events and new information. AWS targets starting a Lambda instance within milliseconds of an event. Node.js, Python, Java and C# through .NET Core are all officially supported as of 2016, and other languages can be supported via call-outs. However, some runtimes, such as the Java Virtual Machine, may be slower than others to start.

Below is a JSON request from the Alexa Skill to the Lambda Function. Note the Lambda function is event driven, so it wakes up with this request, gets the plant data via MQTT from PunNub, builds the response and sends it back to Alexa (with confidential stuff redacted):

{
  "session": {
    "new": true,
    "sessionId": "SessionId.f02ae7fb-5045-4c86-8937-b44a74e63f6e",
    "application": {
      "applicationId": "amzn1.ask.skill.1XXXXX"
    },
    "attributes": {},
    "user": {
      "userId": "amzn1.ask.account.XXXXXXXX"
    }
  },
  "request": {
    "type": "IntentRequest",
    "requestId": "EdwRequestId.3560fc59-308d-41a4-8396-2e56d4781ce3",
    "intent": {
      "name": "temperature",
      "slots": {}
    },
    "locale": "en-US",
    "timestamp": "2017-12-30T00:45:17Z"
  },
  "context": {
    "AudioPlayer": {
      "playerActivity": "IDLE"
    },
    "System": {
      "application": {
        "applicationId": "amzn1.ask.skill.111c1582-8cc3-43af-afb9-984fb01f805a"
      },
      "user": {
        "userId": "amzn1.ask.account.XXXX"
      },
      "device": {
        "supportedInterfaces": {}
      }
    }
  },
  "version": "1.0"
}

And the JSON reply to the Alexa Skill from the Lambda function:

{
  "version": "1.0",
  "response": {
    "outputSpeech": {
      "type": "PlainText",
      "text": "Outside Temperature is 25.9 degrees F"
    },
    "shouldEndSession": true
  },
  "sessionAttributes": {}
}

A valid question at this point, is why the Lambda function doesn’t just subscribe (via MQTT) to the Plant Data channel (SmartPlantPi_Alexa) on PubNub? The reason is that we don’t want the Lambda function to be running all the time (which you need to be running to be a subscriber), we want the Lambda function to awake only on a request from Alexa. Lambda functions are event driven from triggers. Alexa is our trigger in this case. On a technical note, Lambda functions wake up “stateless” every time. The function has no execution to execution built int to the function. You can use an external database (Amazon Elastic Beanstalk for example), but that just increases the cost. Lucky for use, the “state” information we have (the plant information) is stored at PubNub and our Lambda function just grabs it there in the PubNub channel history.

AWS Lambda supports securely running native Linux executables via calling out from a supported runtime such as Node.js.

AWS Lambda usage below a threshold (which we will be under) is free.

SmartPlantPi MQTT Interface

SamrtPlantPi is a set of sensors based on a Raspberry Pi single board computer . We use Python to program this device and the open source code is up on our GitHub.com repository here. As of Version 019+, the Alexa Interface is supported.

After you set up the PubNub keys on SmartPlantPi, you will periodically (every 60 seconds currently) update PubNub via MQTT.

JSON Data Payload

Here is an example of the data packet we are using in the SmartPlantPi code in JSON for the MQTT payload:

 
{
  "SmartPlantPi_Humidity": "32.7",
  "SmartPlantPi_MoistureHumidity": "75.4",
  "SmartPlantPi_Water_Full_Text": "Empty",
  "SmartPlantPi_AirQuality_Sensor_Value": "961",
  "TimeStamp": "01/07/2018 12:24:49",
  "SmartPlantPi_Water_Full_Direction": "180",
  "SmartPlantPi_CurrentStatus": "Sampling",
  "SmartPlantPi_AirQuality_Sensor_Number": "0",
  "SmartPlantPi_Temperature": "71.9 F",
  "SmartPlantPi_UVIndex": "0.85",
  "SmartPlantPi_Last_Event": "Started at: 2018-01-07 12:23:49",
  "SmartPlantPi_Moisture_Threshold": "65.0",
  "SmartPlantPi_Visible": "54.51",
  "SmartPlantPi_AirQuality_Sensor_Text": "Fresh Air",
  "SmartPlantPi_IR": "753.28",
  "SmartPlantPi_Version": "019"
}

Get Your PubNub Keys from your SmartPlantPi Keys

Go to the Keys you setup on PubNub. It should look something like this:

Scroll down on the key page until you see “Storage & Playback”. Enable this. The other default values are fine.

Now you should see this:

Now you are set up on Pubnub. Next we put together the Alexa Skill.

Setting up the Alexa Skill

The Alexa skill talks to the Amazon Echo or other Alexa device in your home. It is a bi-directional link, sending recorded voice for translation to text by the Amazon servers, and then returning text that will be rendered as voice through the Alexa device.

Following are the steps for setting up an Amazon Skill on developer.amazon.com. If you’ve done this before, just copy the intents, and sample utterances, and skip to part 4. Copy and paste your App ID and keep it for Part 4.

We will need to tell the Alexa Skill what phrase (“invocation”) we want it to respond to (“Ask Smart Plantt” in this case),which will activate our app (“skill”) and then what commands (“intents”) to listen for. We also specify what end point it should ping (which we will generate in part 4 – the Lambda Function).

Set up your Free Developer Account

Make a new Account on developer.amazon.com. Make sure you use the same Amazon account name and password that you use on your Echo devices or else you won’t be able to talk to your Alexa Devices.

Once you are logged in you should see a screen like this. Click on the Amazon Alexa link.

Next click on “Add Capabilities to Alexa” as shown below:

Then click on “Start a Skill” and we are off to the races.

Building Your Skill

Now we’ll give Amazon some information about your application. If you want to change some of this, you will be able to do that later. The names you use for this Alexa Skill are unique to your account. If we were to publish this (which we will NOT be doing – it is only for your own account) we would need to have a more unique name.

Leave skill type as “Custom Interaction Model”
Type in “SmartPlantPi Alexa App” for the name
Type in “smart plant” for the invocation (this is what we’ll say to activate this Alexa app)
Leave the other fields at “no”

You should have a screen that looks like this:

Click “save” and then the application ID will be generated. Do a cut and paste and save this application ID. We will need it for the Lambda function. Your screen will then look the this. Note: This application ID below will not work. It has been disabled. You must use your own.

Now click “Next” to continue or on the “Interaction Model” tab to the left.

Enter the Intent Schema and Utterances

When you create a custom skill, you implement the logic for the skill, and you also define the voice interface through which users interact with the skill. To define the voice interface, you map users’ spoken input to the intents your cloud-based service can handle. This is done by inputting Intents and Utterances .

Intents: An intent represents an action that fulfills a user’s spoken request. Intents can optionally have arguments called slots, which we will not be using. The Intents are entered using JSON format (see part 1).
Utterances: A set of likely spoken phrases mapped to the intents. This should include as many representative phrases as possible. This is entered in the form: Name of Intent (from above) on right and the phrase a user might speak to signal that intent on the right.
Custom slot types: A representative list of possible values for a slot. Custom slot types are used for lists of items that are not covered by one of Amazon’s built-in slot types. We are not using this in the SmartPlantPi Skill, but we could.
Dialog model (optional): A structure that identifies the steps for a multi-turn conversation between your skill and the user to collect all the information needed to fulfill each intent. This simplifies the code you need to write to ask the user for information. We will not building a dialog model for our simple skill.

BTW, do NOT CLICK the Launch Skill Builder Beat at this time. If you do, go to the bottom of the Skill Builder and click “opt-out of the bata program”. It’s not ready for what we want to do.

Copy and paste the following JSON into the Intent Schema box. We are building a pretty simple skill with simple intents. These intents will show up as input to our AWS Lambda function in Part 4.

{
  "intents": [
    {
      "intent": "status"
    },
    {
      "intent": "about"
    },
    {
      "intent": "timestamp"
    },
    {
      "intent": "temperature"
    },
    {
      "intent": "humidity"
    },
    {
      "intent": "sunlight"
    },
    {
      "intent": "airquality"
    },
    {
      "intent": "waterlevel"
    },
    {
      "intent": "moisture"
    },
    {
      "intent": "AMAZON.HelpIntent"
    },
    {
      "intent": "default"
    }
  ]
}

Next copy and paste the following into the Sample Utterances Box. Note that they are of the form “intent” “phrase”, where intent is from the above Intent Schema box.

status tell me status
status tell me all
status status
status give me status
status give me all
about about
about tell me about
about tell me about you
about tell me about smart plant
about tell me about smart plant pi
about Where can I buy you
about buy smart plant
about tell me about you
timestamp smart plant timestamp
timestamp timestamp
timestamp when was the last sample taken
timestamp when was the last value
timestamp when was the last sample
temperature tell me temperature
temperature temperature
temperature give me temperature
humidity tell me humidity
humidity humidity
humidity give me humidity
sunlight tell me sunlight
sunlight sunlight
sunlight give me sunlight
airquality tell me air quality
airquality air quality
airquality give me air quality
waterlevel tell me water level
waterlevel water level
waterlevel water
waterlevel does the plant have water
waterlevel what is the water level
moisture tell me moisture
moisture moisture
moisture what is the soil moisture
moisture give me moisture
moisture tell me plant moisture
moisture give me plant moisture
moisture soil moisture
moisture tell me soil moisture
moisture what is soil moisture
AMAZON.HelpIntent help
AMAZON.HelpIntent smart plant help
AMAZON.HelpIntent help me
AMAZON.HelpIntent tell me what you can do
default Pardon

Your screen should now look like the following screen:

Now Click Save and then click Next.

Configuration Screen

This is the screen where we tell Alexa where to go when we send one of our commands. It can be any endpoint or server (we have used it to point to a web server on a Raspberry Pi for example). What we will be doing is pointing it an Amazon Lambda function for simplicity and since we don’t need the function to run all the time. We can use the serverless Lambda function.

We will come back to this screen once we have built our Lambda Function. We’ll come back to enter in the AWS Lambda ARN as the endpoint. Remember to make note of your Alexa app id as we’ll need it in the Lambda code.

Test, Publishing Information and Privacy & Compliance Tabs

We can safely ignore all of the other screens at this point. The Test tab is something we can come back to later.

Now on to the Lambda function!

Now we address the Lambda function on Amazon AWS and hooking it up to SmartPlantPi.

Review: What is a Lambda Function?

The Lambda function is the most difficult to understand part of this project. Why do we need this? An Amazon Alexa Skill is concerned with “utterances” and how to interpret them. When you talk to Alexa, Alexa translates your speech to text, sends a request to the Lambda function. The Lambda function interprets this Alexa JSON request, gathers the plant data via an MQTT history request from PubNub (which came from SmartPlantPi via MQTT), and sends a text response (JSON again) to Alexa with the required plant data embedded, and Alexa speaks the result.

We are using node.js to program the lambda function. Other language, such as C#, Java 8 and Python are available.

What is Node.js?

Node.js is a server-side platform built on Google Chrome’s JavaScript Engine (V8 Engine). Node.js was developed by Ryan Dahl in 2009.

Node.js is an open source, cross-platform runtime environment for developing server-side and networking applications. Node.js applications are written in JavaScript, and can be run within the Node.js runtime on OS X, Microsoft Windows, and Linux.

Node.js also provides a very, very rich library of various JavaScript modules which simplifies the development of web applications.

Features of Node.js

The main features of node.js

Asynchronous and Event Driven − All APIs of Node.js library are asynchronous, that is, non-blocking. It essentially means a Node.js based server never waits for an API to return data. The server moves to the next API after calling it and a notification mechanism of Events of Node.js helps the server to get a response from the previous API call. Since the Lambda function will completely terminate at the end of running your code, we need to use a method for making sure that the Lambda function sticks around for the return of the asynchronous calls. We use a node.js programming construct called “promises” to make that happen. More on promises below.
Very Fast − Node.js library is very fast in code execution.
Single Threaded but Highly Scalable − Node.js uses a single threaded model with event looping. The Event mechanism helps the server to respond in a non-blocking way and makes the server highly scalable as opposed to traditional servers which create limited threads to handle requests. Node.js uses a single threaded program and the same program can provide service to a much larger number of requests than traditional servers like Apache HTTP Server. This programming paradigm fits extremely well with our event-driven Lambda functions.
No Buffering − Node.js applications never buffer any data. These applications simply output the data in chunks. Again, this fits well with Lambda Functions.

Setting up the Lambda Function

Step 1) Sign up for a free account at aws.amazon.com. We would suggest using the same email address as you used for signing up at developer.amazon.com for Alexa, but it is not required. Using the same account you use for you Amazon Alexa (which we used for the Alexa Skill set on developer.amazon.com) is not required as it was for developer.amazon.com since we are not connecting directly from the lambda function to your local Alexa Echo, etc.

You will still require a credit card number, even though we are using the free tier services.

Once you have signed up, you are presented with many, many options. AWS is a very robust and multi-facited cloud server provider. Type “lambda” in the search bar.

Note. Amazon seems to be always changing the initial screens so there may be differences in what you see.

Step 2) Click on “Create Function” and you will see the screen below:

Enter “SDL2Alexa” into the lambda function Name field.

Leave the runtime at the default, “Node.js 6.10”

Click on Creeate Custom Role in the dropdown under “Role”

Leave the defaults on the page below and click “allow”

Now select “lambda_basic_execution” under existing role. Sometimes this page glitches and nothing will show under “Role”. Click on “Create Function”. Now you will have the screen below. Most of these options below, we will not touch.

Next click on Add Triggers-> Alexa Skills Kit and then on “Add” under Configure Triggers.

Finally click on “Save” in the upper right corner of the page. Now, you should have this.

At the top of this screen you will see your ARN (Amazon Resource Name) that we need to connect to the Amazon Alexa Application . Copy the ARN number (behind the “- “) and then open up your Alexa Skill that you set up in Part 3 in another browser (login in to developer.amazon.com). Our example ARN above (which will not work for you, you need your own) was “arn:aws:lambda:us-west-2:770035828910:function:Alexa2SPP”.

Click on the configuration tab in your SmartPlantPi Alexa App from above and click on the radio button “AWS Lambda ARN” and then enter your ARN number as the default under endpoint as below:

Our Alexa Skill configuration is now complete. We now go back to the Lambda function and install our software.

Add the Alexa Skills Kit Trigger, if it isn’t shown. (Add triggers->Alexa Skill Kit, then Add). Now finally, click on the SDL2Alexa button at the top of the Designer Block to look at your code.

Your Lambda screen should now look like this:

Now we can install the Lambda Software

Installing the Lambda SoftwareAlexa2SDLSPP

We have the Lambda software and all required libraries, here in a zip file. Download this to your computer.

Under Function code, click on the drop down “Code entry type” and select “Upload a .ZIP file”. Then click on Upload and select the Zip file from your computer you just downloaded. It should be “SDL2AlexaOW.zip”.

If you are on a Mac, it may automatically unzip the file, in which case go into the SDL2AlexaOW directory, select all the files, right click, and compress it again (it will be archive.zip in the program directory).

The Click “Save” in the top right corner.

Now go down to the Function code block to the Code entry type dropdown and select “Edit code inline” and you should now see this:

Configure the Lambda Function

Almost done now. We have a couple of things to configure in the Lambda code. In the function code block

Step 1) Grab your PubNub Subscribe code (from your PubNub key screen from above) and paste it into the text slot string for pub_key and sub_key. Your code should like this after doing this. (Note: Don’t use these keys, use your keys).

var pubnub =  new PubNub({
    ssl           : true,  
    publish_key   : "pub-c-5a1f3909-6b99-4b64-8c74-a4c32b26930e",
    subscribe_key : "sub-c-99f9827e-448e-11e7-bc55-0619f8945a4f",
 
});
var channel = 'SmartPlantPi_Alexa';

Step 2) Put in the Alexa Skill ID. The one below will NOT WORK. You must grab your Alexa Skill Application ID (see the Alexa Skill you built above- it will be under the Skill Information Tab in your Alexa App).

Now that part of the lambda code should look like this:

/**
 * App ID for the skill
 */
var APP_ID = 'amzn1.ask.skill.2ff2989c-6a37-4166-9f69-b16e9545dab8'; //replace with "amzn1.echo-sdk-ams.app.[your-unique-value-here]";

That is it for configuration. Save the function. Now on to testing.

Testing the Alexa Skills

OK. Back to the Alexa Skill. Go to the “Test” tab and enable the test if you haven’t already.

Down in the Service Simulator in the text tab, type “temperature” and click, “Ask SmartPlantPi Alexa App”. You will get a failure for the Service response (we have no data yet because we haven’t set up SmartPlantPi yet), but what we really want is the JSON Service request. We are going to use that in the Lambda Function test. Copy all of the JSON code out of the Service Request. It will look something like this (this code BELOW WILL NOT WORK! – You must get your own):

{
  "session": {
    "new": true,
    "sessionId": "SessionId.e378cb07-fc7a-4464-8ad6-f3e12e52610d",
    "application": {
      "applicationId": "amzn1.ask.skill.83324277-3dda-4a60-91f4-4657da0e92f0"
    },
    "attributes": {},
    "user": {
      "userId": "amzn1.ask.account.AH"
    }
  },
  "request": {
    "type": "IntentRequest",
    "requestId": "EdwRequestId.8c2fda51-30ce-48e4-abe5-411055b524ce",
    "intent": {
      "name": "temperature",
      "slots": {}
    },
    "locale": "en-US",
    "timestamp": "2018-01-07T22:12:32Z"
  },
  "context": {
    "AudioPlayer": {
      "playerActivity": "IDLE"
    },
    "System": {
      "application": {
        "applicationId": "amzn1.ask.skill.83324277-3dda-4a60-91f4-4657da0e92f0"
      },
      "user": {
        "userId": "amzn1.ask.account.AH"
      },
      "device": {
        "supportedInterfaces": {}
      }
    }
  },
  "version": "1.0"
}

Now let’s go test the Lambda Function.

Testing the the Lambda Function

Click on the drop down menu next to the test button and select “Configure test events”. On the next screen, call your Event name, “Temperature” and then paste the JSON Service Request code from the previous step.

Clicking the Test button now will show a failure. We need to load up some data on PubNub first for the Lambda Function to work.

Setting a Dummy PubNub Message

After we set up SmartPlantPi in the next Part, we will have live data to work on. But right now, let’s publish a message that the Lambda Node will be able to pick up. Here is a JSON message from SmartPlantPi to PubNub that we will use in our testing.

{
  "SmartPlantPi_Humidity": "33.3",
  "SmartPlantPi_MoistureHumidity": "76.4",
  "SmartPlantPi_Water_Full_Text": "Empty",
  "SmartPlantPi_AirQuality_Sensor_Value": "774",
  "TimeStamp": "01/07/2018 14:21:49",
  "SmartPlantPi_Water_Full_Direction": "180",
  "SmartPlantPi_CurrentStatus": "Sampling",
  "SmartPlantPi_AirQuality_Sensor_Number": "0",
  "SmartPlantPi_Temperature": "71.6 F",
  "SmartPlantPi_UVIndex": "0.75",
  "SmartPlantPi_Last_Event": "Started at: 2018-01-07 12:23:49",
  "SmartPlantPi_Moisture_Threshold": "65.0",
  "SmartPlantPi_Visible": "57.38",
  "SmartPlantPi_AirQuality_Sensor_Text": "Fresh Air",
  "SmartPlantPi_IR": "688.93",
  "SmartPlantPi_Version": "019"
}

Go to your PubNub account (that you set up when you connect SmartPlantPi to your dashboard) and go down into your SDL2Alexa App and then select your subscribe key from the SmartPlantPi Key (you should have this saved somewhere else too).

Next, Click on the side tab to Debug Console. Make the Default channel “SmartPlantPi_Alexa” and place your pub-sub key into the Authorization key. Click on Add Client. Make sure you get the channel right!

Now you should have a screen that looks like this:

Paste the JSON message from SmartPlantPi (above) into the Test Message slot and press Send. You should then look like this:

Now our Lambda will have something to chew on.

Go back to to your Lambda page and click on Test (running the Temperature Test that we sent up earlier!).

Look down at the Execution Results in the Function code block and you should have your first success full Response.

Now let’s go back to the Alexa Skill.

Go back to the Service Simulator, type “Temperature” into the Enter Utterance box and hit the “Ask SmartPlantPi Alexa App”. Now you have connected all the way from your Alexa Skill to your Lambda Function, which reads the PubNub channel and sends back the temperature. 35.8 Degrees. Hit the listen button to hear what it would sound like on your Echo. Sometimes the browser aren’t quite wired into the speaker on some computers, so don’t be surprised it if doesn’t work.

One More Test – Try Your Alexa

OK, now the rubber hits the road. We have the Alexa Skill working, we have the Lambda Function working, let’s go to your phone and add the Alexa App. Note you must be logged into the same email address and account for your Alexa App on your phone (and have registered your Echos to the same account (email address) for your app to show up.

On the iPhone, Click the menu, then select Skills. Then click on Your Skills at the top right. Look under All Skills or just updated and you will find your new skill (SmartPlantPi in this case). Select your new skill. Finally slide over the tabs from Recently Added all the way to the right and you should see DEV SKILL. Click that and you should see something like this (OurWeather is another SwitchDoc Labs Kit):

Next is the big moment. Ask Alexa “Alexa, Ask Smart Plant Temperature”. You should be rewarded as below. Next we we hook up real environmental data from the SmartPlantPi Kit to our system.

The Lambda Node.js Intent Software – Promises, Promises!

Before we move on to Part 5, we wanted to talk a little about the Lambda node.js code. If you recall, lambda functions quit when they stop running code. This is a problem for a node.js program that deals with asynchronous callbacks. In our lambda code, we request a history on the the SmartPlantPi station channel, SmartPlantPi_Alexa from the MQTT channel on PubNub. This takes a while to come back (on the order of 100ms or so) and if we don’t stop the lambda function somehow, it will stop before the callback comes back because of the nature of a node.js program. How to solve this?

The key is Promises. We essentially make the node.js lambda function “promise” to wait until the callback routine returns (or the 3 to 7 second default lambda function time out happens). When the callback is processed (the promise being kept) and the response is then sent to the Alexa skill and the lambda function terminates.

What are Promises?

The core idea behind promises is that a promise represents the result of an asynchronous operation. A promise is in one of three different states:

pending – The initial state of a promise.
fulfilled – The state of a promise representing a successful operation.
rejected – The state of a promise representing a failed operation.

Once a promise is fulfilled or rejected, it is immutable (i.e. it can never change again).

An example promise for the “temperature” intent in the SDL2Alexa lambda code:

// temperature intent
temperature: function (intent, session, response) {

var first = pubnub.history({
    channel: channel,
    reverse: false, // Setting to true will traverse the time line in reverse starting with the oldest message first.
    count: 1, // how many items to fetch

}).then((response) => { 


    var obj = JSON.parse(JSON.stringify(response));

    var msgs = obj.messages;
    var msg = msgs[0];
    var parsedJSON = JSON.parse(JSON.stringify(msg.entry));
    JSONMessage = parsedJSON;
	return;



    
}).catch((error) => { 
    console.log(error) 
});

  return Promise.all([first])
        .then(function (responses) {
            var myText;
            var myTemp;
            myTemp = JSONMessage.SmartPlantPi_Temperature;
            myTemp = myTemp.replace(" ", " degrees ");
                 myText = "Inside Temperature is " + myTemp;
         
	             response.tell(myText);


            return ;
        });

    },

The syntax is somewhat obscure, but you can see the return from the history call (the”first” function) is in the Promise.all function call that waits for the history PubNub return and builds the response for the Alexa Skill.

What’s Next? Tying it all together.

Start SmartPlantPi

There is no configuration left for SmartPlantPi. Just start the program running.

Testing

First we can check to see that your MQTT message is getting to PubNub. Go to your PubNub account (that you set up in Part 2) and go down into your SDL2Alexa App and then select your subscribe key from the SmartPlantPi Key (you should have this saved somewhere else too).

Next, Click on the side tab to Debug Console. Make the Default channel “SmartPlantPi_Alexa” and place your pub-sub key into the Authorization key. Click on Add Client.

Now you should have a screen that looks like this:

Wait a few minutes and you should receive an JSON MQTT message from SmartPlantPi as below:

You are wired up!

Full System Test

Well, now after setting up the Alexa Skill, the Lambda Function, PubNub and SmartPlantPi we are ready to go for our full system test.

Say “Alexa, Ask Smart Plant status”

You should hear the following, with your information:

Coming Next

We are next adding Alexa to our GroveWeatherPi project. Talk to your Raspberry Pi Weather Station!

SwitchDoc Labs Blog

For Makers, by a Maker

Tutorial: Voice Time! SmartPlantPi, Raspberry Pi and Amazon Alexa

Tutorial: Voice Time! SmartPlantPi, Raspberry Pi and Amazon Alexa

What is SmartPlantPi?

How does the SmartPlantPi to Alexa Interface Work?

The Alexa Voice to SmartPlantPi Project

What is MQTT?

What is JSON?

The Four Blocks of the Alexa Voice to SmartPlantPi Project

PubNub

The Alexa Skill

The AWS Lambda Serverless Function

SmartPlantPi MQTT Interface

JSON Data Payload

Get Your PubNub Keys from your SmartPlantPi Keys

Setting up the Alexa Skill

Set up your Free Developer Account

Building Your Skill

Enter the Intent Schema and Utterances

Configuration Screen

Test, Publishing Information and Privacy & Compliance Tabs

Review: What is a Lambda Function?

What is Node.js?

Features of Node.js

Setting up the Lambda Function

Installing the Lambda SoftwareAlexa2SDLSPP

Configure the Lambda Function

Testing the Alexa Skills

Testing the the Lambda Function

Setting a Dummy PubNub Message

One More Test – Try Your Alexa

The Lambda Node.js Intent Software – Promises, Promises!

What are Promises?

Start SmartPlantPi

Testing

Full System Test

Coming Next

Related