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Posted 26 Apr 2018
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Wind River Helix Device Cloud Application Deployment: POC Retail Vending Machine

, 26 Apr 2018
This article will explore a proof of concept that leverages the capabilities of Helix Device Cloud (HDC) and uses the UP Squared board as the vending machine gateway.

Editorial Note

This article is in the Product Showcase section for our sponsors at CodeProject. These articles are intended to provide you with information on products and services that we consider useful and of value to developers.

Intro

Securely and easily managing an IOT software solution on multiple gateways across the world can be a challenge. However, for gateways running Wind River Helix Device Cloud* there is a clear path to follow that diminishes the challenge. The Wind River Helix Device Cloud allows for complete device lifecycle management, from deploying, to monitoring, to updating, to decommissioning. Wind River Helix Device Cloud has telemetry capabilities as well, allowing it to receive and store data in the cloud, as well as act on data using triggers and alarms. This article will explore a proof of concept that leverages the capabilities of Helix Device Cloud (HDC) and uses the UP Squared* board as the vending machine gateway. HDC will allow the stock of the vending machine to be monitored and set up of automated triggers to restock it automatically as well as view the stock data in a dashboard.

To learn more about the Helix Device Cloud:
https://www.helixdevicecloud.com

To learn more about the UP Squared Board:
https://software.intel.com/en-us/iot/hardware/up-squared-grove-dev-kit

Figure 1: High Level Component Diagram with UP Squared, Grove* Sensors, and Helix Device Cloud

Helix Device Cloud*

This section will be a brief overview of the Helix Device Cloud and the pieces needed for this POC. For a more in-depth guide see https://knowledge.windriver.com/en-us/000_Products/040/080/000/000_Wind_River_Helix_Device_Cloud_Getting_Started

There are two main parts to configure in the Helix Device Cloud, the Thing Definition and Application. Both of these are found under the developer tab (see Figure 2).

A Thing Definition defines the characteristics of the IOT solution: attributes, alarms, properties, methods, and more.

  • Attributes are for string data that is typically static, like OS version or MAC id.
  • Properties are for integer values that will change over time such as temperature.
  • Alarms are for events and alerts, like signaling the temperature is too high.
  • Methods define a behavior to invoke on the device or client application, like rebooting the device or sending more stock to the vending machine. Methods are implemented in code on the device level but can be triggered from the cloud.

Application defines how the thing is going to be used, with different levels of access and privilege. With this model, there can be multiple Applications for one Thing Definition, for example one with ‘Org Admin’ privileges and one without. Each client application running on the device will also receive its own unique device id. This combined with the application name will create the key for the application in the cloud. The recommended model is to have a separate Device Manager application from the client application to keep certain permissions like ‘reboot’ and ‘decommission’ device separate.

Figure 3, located below, outlines these key parts.

Figure 2: Where to find Application and Thing Definitions

Figure 3: Diagram of Components on Device and in the Cloud

Set-up

This article assumes that chocolate bar vending machines have been deployed in various locations, and that they’re controlled by a gateway with the HDC agent installed and a Device Manager Application running. The Device Manager has the ability to send and receive files, reboot the device, remotely log in, update device software, and more. The POC uses the UP Squared board running Ubuntu* 16.04 Server OS (comes installed by default on the board). The vending machine functionality is provided by the Wind River Helix Device Cloud Python agent, and Grove* sensors from Seeed* Studio. The UP Squared board has a button sensor to indicate a purchase of the product. It also uses LEDS as indicators. A green LED turns on when purchase is successful and a red LED turns on when the product is out of stock. A temperature sensor will monitor the vending machine’s temperature to see if the chocolate bars are in danger of melting. In addition, it has a motion sensor to count traffic passing by the vending machine which turns on a blue LED when motion is detected. The software for the vending machine is written in Python* and uses the HDC python device cloud API.

For instructions on how to install and configure the HDC Agent and the sample Device Manager Application on Ubuntu, refer to this guide in the Wind River Knowledge Library:

https://knowledge.windriver.com/en-us/000_Products/040/080/000/000_Wind_River_Helix_Device_Cloud_Quick_Start_for_Linux

Additionally, see the link below for how to import the sample Device Manager Application and Thing Definition into HDC.

https://github.com/Wind-River/device-cloud-python/tree/7d1e970732421aed1b1e70b727700bfada4edfd9/share/admin-tools

To interface with the Grove sensors, MRAA and UPM need to be installed on the UP Squared board. If they’re not present, use these commands:

sudo add-apt-repository ppa:mraa/mraa
sudo apt-get update
sudo apt-get install libmraa1 libmraa-dev mraa-tools python-mraa python3-mraa
sudo apt-get install libupm-dev libupm-java python-upm python3-upm node-upm upm-examples
Code 1: Commands to Install MRAA and UPM on Ubuntu

In the Helix Device Cloud, the Thing Definition needs to be added for the POC Vending Thing. Figure 4 shows the full overview of the thing, including alarms and the states to configure. There is a chocobar_out_of_stock alarm for alerting that all the chocolate bars have been sold. Figure 5 shows the telemetry properties, the data being collected is telemetry_motion, telemetry_temp, and telemetry_stock_chocobars. Figure 6 shows the method, method_restock, which needs to be configured so that the chocolate bars can be restocked. The fields labeled ‘Key’ are what will be used in the code in the client application. Note that Thing Definition can also be exported and imported as json files, so alternatively import thing_defs.json as shown in Code 2 and update it with your org id instead of manually inputting everything.

Figure 4: POC Vending Thing Definitions and Alarms View

Figure 5: POC Vending Thing Definitions Properties Figure 6: POC Vending Thing Definitions Methods

Figure 6: POC Vending Thing Definitions Methods
[{"ownerOrgId":"yourOrgIdHere","key":"poc_vending_thing","name":"POC Vending Thing","version":13,"autoDefProps":true,"autoDefAttrs":true,"properties":{"telemetry_motion":{"name":"auto:telemetry_motion","calcAggregates":false},"telemetry_stock_chocobars":{"name":"auto:telemetry_stock_chocobars","calcAggregates":false},"telemetry_temp":{"name":"auto:telemetry_temp","calcAggregates":false}},"alarms":{"chocobar_out_of_stock":{"name":"Chocolate Bars Out of Stock","states":[{"name":"Out of Stock","color":"#E61717"},{"name":"Stock Available","color":"#3BBD1B"}]},"high_temp":{"name":"High Temperature Alarm","states":[{"name":"Melted","color":"#EB0505"},{"name":"Normal","color":"#46E61E"}]}},"methods":{"method_restock":{"name":"Restock Chocolate Bars","description":"Send more stock to the vending machine","notificationVariables":{"num_chocobars_sent":{"name":"num_chocobars_sent","type":"int","uiType":"text"}}}}}]
Code 2: thing_def.json for Importing the Thing Definition

Next, configure the Application definition and link it to the POC Vending Thing Definition as per Figure 7. An Application token will automatically be generated after creation, see Figure 8. The token will be used on the device so the client application will know which Application and Thing Definition it will be using.

Figure 7: POC Vending Application

Figure 8: POC Vending Application View

Vending Machine Telemetry

The data collected from the vending machine is where the real value comes into play. The gateway application will collect motion, temperature, and inventory data, and send it to the Helix Device Cloud. The application is a python script ‘iot-poc-vending.py’ that will be turned into a service. Then in HDC, a variety of triggers and alarms can be set up to handle the values coming in. For example, if inventory runs out, a trigger can be set up to send more inventory out to the machine automatically. The Grove sensors will supply the data to upload. To interface with sensors through the Grove shield, add the line below in the code. This will tie into MRAA and GROVEPI. GROVEPI will allow the sensors to talk to the gateway, and MRAA handles the IO pin communications. Note that root access is required to access the shield by default, so when running the python script, it must be run as sudo.

import upm
import mraa
# Interface with Grove Sensors
mraa.addSubplatform(mraa.GROVEPI, "0")
Code 3: Line to Have MRAA use GROVEPI

Using GROVEPI will shift all the pin numbers by 512, so pin A0 for the temperature sensor is really pin 512 + 0.

Grove shield pins:

  • Temperature sensor: A0
  • Button sensor: D8
  • Motion sensor: D7
  • Blue motion indicator LED: D2
  • Red out of stock indicator LED: D4
  • Green purchase indicator LED: D3
temperature_sensor = grove.GroveTemp(512 + 0)
button_sensor = grove.GroveButton(512 + 8)
motion_sensor = upmMotion.BISS0001(512 + 7)
blue_motion_led = grove.GroveLed(512 + 2)
red_stock_led = grove.GroveLed(512 + 4)
green_stock_led = grove.GroveLed(512 + 3)
Code 4: Grove Sensor Initialization Code

The program’s loop will gather the sensor data, handle items being purchased, publish alarms as needed, and then send data to HDC every 10 seconds.

counter = 0
    while running and client.is_alive():
        counter += 1
			
        #purchase flow
        green_stock_led.off()
        customer_purchase = button_sensor.value()
        if (stock_chocobars > 0):
            red_stock_led.off()
            if (customer_purchase):
	client.info("Customer purchasing item")
                green_stock_led.on()
                stock_chocobars -= 1
        else:
            red_stock_led.on()
            client.alarm_publish("chocobar_out_of_stock", 0)
        current_motion= motion_sensor.value()
        if(current_motion):
            motion +=1
            blue_motion_led.on()
        else:
            blue_motion_led.off()
        celsius = temperature_sensor.value()
        fahrenheit = celsius * 9.0/5.0 + 32.0;	
        if (fahrenheit >= 90):
            client.alarm_publish("high_temp", 0)
        if counter >= TELEMINTERVAL:
            send_telemetry()
            # Reset counter after sending telemetry
            counter = 0
        sleep(1)
Code 5: The Main Loop of the Program

To send telemetry to HDC, it is one line of code using telemetry_publish. If the property is not registered in HDC already, publish will fail on the first try and then it will auto register the property (if enabled in the Thing Definition, refer back to Figure 4).

# temperature telemetry to send
	client.info("Publishing Property: %s to %s", fahrenheit, "telemetry_temp")
	ts = datetime.datetime.utcnow()
	status = client.telemetry_publish("telemetry_temp", fahrenheit, cloud_response, timestamp=ts)
	# Log response from cloud
	if cloud_response:
		if status == iot.STATUS_SUCCESS:
			client.log(iot.LOGINFO, "Telemetry Publish - SUCCESS")
		else:
			client.log(iot.LOGERROR, "Telemetry Publish - FAIL")
Code 6: Code Needed for each Telemetry Metric

Properties can be seen in the thing view in the Helix Device Cloud in graph form.

Figure 9: Thing View in HDC

Methods

Methods can be called from the cloud directly, or called automatically with Triggers, which will be discussed in the next section.
In addition to configuring the method in the cloud, the function to call must be registered in the client application so HDC knows which function to execute when it is called.

client.action_register_callback("method_restock", method_restock)
Code 7: Register the Callback Function for the Method

Next, add the function for what to do when the method call is received from the gateway. Here it is mimicking restocking the chocolate bars, so the sent number will be added to the current stock value.

def method_restock(client, params):
    """
    Restocks Chocolate Bars
    """
    global stock_chocobars

    message = params.get("num_chocobars_sent")
    stock_chocobars += message
	
    p = {}
    p['chocobars'] = "RESTOCKED"

    msgstr = "Chocolate Bars Restocked"
    client.info(msgstr)
    client.event_publish(msgstr)
    return (iot.STATUS_SUCCESS, "", p)
Code 8: Code to Handle Method Received from HDC

Triggers

Now that the data and methods have been set up in the cloud and on the device, the triggers feature can be leveraged. This will help monitor the vending machine when data is received for conditions that require attention.

The vending machine needs to send out an email alert if the temperature gets too high, as the chocolate inside might melt. To create a new rule, go to the Developer -> Triggers and click on New Trigger.

Name the trigger ‘POC Vending High Temperature Alarm’. Right click on the trigger event and choose Event type of alarm.change, add the Thing key, Alarm Key of high_temp, Alarm State of 0 for melted as configured back in the Thing Definition, and 0 as the Time in condition (see Figure 10). From the Trigger actions menu on the side, go into Networking and drag out email.send node. Alternatively, http, mqtt, or sms messages could be sent instead. Configure the email node with the message, subject, and to email (see Figure 11). Then, at the bottom of the Trigger actions, expand End and drag out a Success and Failure node. Lastly click on the triangles at the bottom of the nodes and drag it to appropriate node (see Figure 12 as reference). Now that the Trigger has been created, view it and click on Start to activate it.

Figure 10: Config of Initial Trigger Event

Figure 11: Email Configuration for the Trigger

Figure 12: Node Flow of the High Temperature Alarm Trigger

The Trigger to auto restock the chocolate bars is very similar except with an added method.exec node from the Method actions and an alarm.publish from Alarm. Select the POC Vending Thing as the Thing Definition. This is how it knows which methods are available. Then select method_restock as the method. Add the Thing Key to execute the method on, the Ack Timeout, and the method input (which is num_chocobars_sent). Also add the alarm.publish to change the alarm state of chocobar_out_of_stock to 1 to indicate they are back in stock now. See Figure 13, 14, and 15 for reference.

Figure 13: Config of method.exec for Auto Restocking

Figure 14: Config of alarm.publish to Change Alarm State back to Chocobars in Stock

Figure 15: Node Flow of the Method Restock Trigger

Figure 16: Triggers for Restocking and High Temperature are Started

Deployment

There are 4 files needed to run the client application on the device: iot-vending-connect.cfg, iot-poc-vending.py, device_id, and HDC_VendingMachine.service. The service file will turn the code into a service running continuously on the gateway, even after reboot. The device_id file should already be on the device in the device-cloud folder. The iot-vending-connect.cfg will link the application up to cloud and contains the HDC host name and the Application Token; see the getting started guide and Code 9 for more information. Make sure device_id and iot-vending-connect.cfg are in the same directory and update the config_dir in iot-poc-vending.py to their location.

{
  "cloud": {
    "host": "yourHostName", 
    "port": 8883, 
    "token": "yourAppToken"
  }, 
  "qos_level": 1, 
  "validate_cloud_cert": true
}
Code 9: iot-vending-connect.cfg file
#!/usr/bin/python
from __future__ import print_function
import argparse
import errno
import random
import signal
import sys
import os

import math
import mraa
import time, sys, signal, atexit
from upm import pyupm_grove as grove
from upm import pyupm_biss0001 as upmMotion
# Interface with Grove sheild
mraa.addSubplatform(mraa.GROVEPI, "0")

import datetime
import time
from time import sleep
head, tail = os.path.split(os.path.dirname(os.path.realpath(__file__)))
sys.path.insert(0, head)
import device_cloud as iot
#from device_cloud import osal

B=3975

temperature_sensor = grove.GroveTemp(512 + 0)
button_sensor = grove.GroveButton(512 + 8)
motion_sensor = upmMotion.BISS0001(512 + 7)
blue_motion_led = grove.GroveLed(512 + 2)
red_stock_led = grove.GroveLed(512 + 4)
green_stock_led = grove.GroveLed(512 + 3)

running = True

# Return status once the cloud responds
cloud_response = False

# Second intervals between telemetry
TELEMINTERVAL = 10

def sighandler(signum, frame):
    """
    Signal handler for exiting app
    """
    global running
    if signum == signal.SIGINT:
        print("Received SIGINT, stopping application...")
        running = False

def method_restock(client, params):
    """
    Restocks Chocolate Bars
    """
    global stock_chocobars

    message = params.get("num_chocobars_sent")
    stock_chocobars += message
	
    p = {}
    p['chocobars'] = "RESTOCKED"

    msgstr = "Chocolate Bars Restocked"
    client.info(msgstr)
    client.event_publish(msgstr)
    return (iot.STATUS_SUCCESS, "", p)

def send_telemetry():
	global motion, stock_chocobars, temperature
	# temperature telemetry to send
	client.info("Publishing Property: %s to %s", fahrenheit, "telemetry_temp")
	ts = datetime.datetime.utcnow()
	status = client.telemetry_publish("telemetry_temp", fahrenheit, cloud_response, timestamp=ts)
	# Log response from cloud
	if cloud_response:
		if status == iot.STATUS_SUCCESS:
			client.log(iot.LOGINFO, "Telemetry Publish - SUCCESS")
		else:
			client.log(iot.LOGERROR, "Telemetry Publish - FAIL")
	# motion telemetry to send
	client.info("Publishing Property: %s to %s", motion, "telemetry_motion")
	ts = datetime.datetime.utcnow()
	status = client.telemetry_publish("telemetry_motion", motion, cloud_response, timestamp=ts)
	motion = 0
	# Log response from cloud
	if cloud_response:
		if status == iot.STATUS_SUCCESS:
			client.log(iot.LOGINFO, "Telemetry Publish - SUCCESS")
		else:
			client.log(iot.LOGERROR, "Telemetry Publish - FAIL")	
       # chocolate bar stock telemetry to send	
	client.info("Publishing Property: %s to %s", stock_chocobars, "telemetry_stock_chocobars")
	ts = datetime.datetime.utcnow()
	status = client.telemetry_publish("telemetry_stock_chocobars", stock_chocobars, cloud_response, timestamp=ts)
	# Log response from cloud
	if cloud_response:
		if status == iot.STATUS_SUCCESS:
			client.log(iot.LOGINFO, "Telemetry Publish - SUCCESS")
		else:
			client.log(iot.LOGERROR, "Telemetry Publish - FAIL")

if __name__ == "__main__":
    global motion, stock_chocobars, temperature
    stock_chocobars = 2
    temperature = 0
    motion = 0

    signal.signal(signal.SIGINT, sighandler)

    # Initialize client 
    app_id = "iot-poc-vending"
    client = iot.Client(app_id)

    # Use the .cfg file inside the directory
    config_file = "iot-vending-connect.cfg"
    client.config.config_file = config_file

    # Look in this directory
    config_dir = "/home/upsquared/device_cloud/demo/"
    client.config.config_dir = config_dir

    # Finish configuration and initialize client
    client.initialize()

    # Set action callbacks
    client.action_register_callback("method_restock", method_restock)

    # Connect to Cloud
    if client.connect(timeout=10) != iot.STATUS_SUCCESS:
        client.error("Failed")
        sys.exit(1)

    counter = 0
    while running and client.is_alive():
        counter += 1
			
        #purchase flow
        green_stock_led.off()
        customer_purchase = button_sensor.value()
        if (stock_chocobars > 0):
            red_stock_led.off()
            if (customer_purchase):
				client.info("Customer purchasing item")
                green_stock_led.on()
                stock_chocobars -= 1
        else:
            red_stock_led.on()
            client.alarm_publish("chocobar_out_of_stock", 0)
        current_motion= motion_sensor.value()
        if(current_motion):
            motion +=1
            blue_motion_led.on()
        else:
            blue_motion_led.off()
        celsius = temperature_sensor.value()
        fahrenheit = celsius * 9.0/5.0 + 32.0;	
        if (fahrenheit >= 90):
            client.alarm_publish("high_temp", 0)
        if counter >= TELEMINTERVAL:
            send_telemetry()
            # Reset counter after sending telemetry
            counter = 0
        sleep(1)
		
    client.disconnect(wait_for_replies=True)
Code 10: Full Code for iot-poc-vending.py

The HDC_VendingMachine.service file is shown below. The service should start after the network.target starts, and then start the python code. Place this file in /lib/systemd/system/ with sudo cp.

[Unit]
Description=HDC POC
After=network.target
 
[Service]
ExecStart=/home/upsquared/device_cloud/demo/iot-poc-vending.py
Restart=always
User=root
StandardOutput=journal
StandardError=journal
KillMode=process
KillSignal=SIGINT
 
[Install]
WantedBy=multi-user.target
Code 11: HDC_Vendingmachine.service File

Make the python file and the service file executable, and then enable and start the service. Look in /var/log/syslog for any errors on startup, and also for the info logs from the application.

chmod +x /home/upsquared/device_cloud/demo/iot-poc-vending.py
chmod +x /lib/systemmd/system/HDC_VendingMachine.service
Code 12: Change iot-poc-vending.py to Executable
sudo systemctl enable HDC_VendingMachine.service
sudo systemctl start HDC_VendingMachine.service 
Code 13: Enable and Start the Service

Dashboard

Now that the client app is configured in the cloud, and running on the device, a dashboard can be setup to see the data, alarms, and other important information at a glance. There is some customization available with layout and colors, however it is designed more for testing not as an industrial grade solution.

When creating the dashboard, only Name, Thing definition, and Date/Time are required.

Figure 17: POC Vending Telemetry Dashboard Setup

Next, the layout can be designed as wanted with different dashboard widget types. The property graph widget is used for all three of the telemetry properties: temperature, stock, and motion. The current alarm state widget is used for the Temperature alarm and the Alarm History for the out of stock alarm.

Figure 18: Dashboard Layout Design

Each widget needs to be configured with the Thing Key and property or alarm to display.

Figure 19: Property Graph Widget for Temperature

Figure 20: Current Alarm State widget for Temperature Alarm

The final dashboard with the data and alarms looks like Figure 21 below.

Figure 21: Dashboard View

Summary

Our vending machine code has now been successfully deployed on Helix Device Cloud. Temperature and stock data is being monitored with automated triggers. Motion data can be referenced as time goes on to monitor foot traffic around the vending machine. Any future updates to the program and overall gateway health can be deployed and monitored using HDC.

To purchase HDC visit https://www.windriver.com/company/contact/index.html or email sales@windriver.com

Purchase

About the Author

Whitney Foster is a software engineer at Intel in the Software and Services Group working on scale enabling projects for Internet of Things.

Notices

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Intel disclaims all express and implied warranties, including without limitation, the implied warranties of merchantability, fitness for a particular purpose, and non-infringement, as well as any warranty arising from course of performance, course of dealing, or usage in trade.

This document contains information on products, services and/or processes in development. All information provided here is subject to change without notice. Contact your Intel representative to obtain the latest forecast, schedule, specifications and roadmaps.

The products and services described may contain defects or errors known as errata which may cause deviations from published specifications. Current characterized errata are available on request.

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*Other names and brands may be claimed as the property of others
© 2018 Intel Corporation.

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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