Stream Sensor Data In Real-Time With IoT Hub Using PowerBI

Introduction

This article demonstrates how to send the temperature data into the cloud via Azure IoT Hub and PowerBI.

Requirement

DHT11 - Temperature and Humidity Sensor Module
Azure Subscription
Analysis - IoT - Hub (8,000 messages per day)
Power PI Account
Raspberry Pi
Stream Analytics Job

DHT11 - Temperature and Humidity Sensor Module

The DHT11 humidity and temperature sensor make it really easy to add humidity and temperature data to your IoT Hub.

Item	Measurement Range	Humidity Accuracy	Temperature Accuracy	Resolution	Package
DHT11	20-90%RH 0-50 ℃	±5％RH	±2℃	1	4 Pin Single Row

Raspberry Pi and dh11 interconnection diagram

Step 1

Navigate to IoT devices within your IoT Hub.
Click "Add".
Populate the Device ID (e.g. raspberrypi).
Click "Save".

Create an IoT device named as "raspberrypi" and select the authentication type.

Create a Consumer Group

Navigate to Endpoints within your IoT Hub.
Click on the Events (messages/events) endpoint.
Add a Consumer Group (e.g. streamanalytics_consumergroup).
Click "Save".

Step 2

Create a Stream Analytics job; the job name is Stream - Analysis.

Step 3

Navigate to Input alias.
Select IoT Hub from your subscriptions.
Add a Consumer Group (e.g. streamanalytics_consumergroup).
Endpoint (ex: Message).
Click "Save".

Step 4

Navigate to Outputs.
Click Add > Power BI.

Output alias (e.g. powerbioutput).
Dataset Name (e.g. temperatureDataset).
Table Name (e.g. temperatureTable).
Click "Authorize".
Click "Save".

Stream Analytics SQL

Navigate to Query within Stream Analytics.
Copy and paste the SQL below into your Stream Analytics query window.
Sample data has returned, click "Test".
Click "Save".
Click "Start".
1. SELECT
2. CAST(iothub.EnqueuedTime AS datetime) AS event_date,
3. CAST(temp AS float) AS temp
4. INTO
5. powerbioutput
6. FROM
7. iothubinput

Source Code (Python)

from base64 import b64encode, b64decode
from hashlib import sha256
from urllib import quote_plus, urlencode
from hmac import HMAC
import requests
import json
import os
import time
# Temperature Sensor
BASE_DIR = '/sys/bus/w1/devices/'
SENSOR_DEVICE_ID = 'YOUR_DEVICE_ID'
DEVICE_FILE = BASE_DIR + SENSOR_DEVICE_ID + '/w1_slave'
# Azure IoT Hub
URI = 'YOUR_IOT_HUB_NAME.azure-devices.net'
KEY = 'YOUR_IOT_HUB_PRIMARY_KEY'
IOT_DEVICE_ID = 'YOUR_REGISTED_IOT_DEVICE_ID'
POLICY = 'iothubowner'
def generate_sas_token():
expiry=3600
ttl = time.time() + expiry
sign_key = "%s\n%d" % ((quote_plus(URI)), int(ttl))
signature = b64encode(HMAC(b64decode(KEY), sign_key, sha256).digest())
rawtoken = {
'sr' : URI,
'sig': signature,
'se' : str(int(ttl))
}
rawtoken['skn'] = POLICY
return 'SharedAccessSignature ' + urlencode(rawtoken)
def read_temp_raw():
f = open(DEVICE_FILE, 'r')
lines = f.readlines()
f.close()
return lines
def read_temp():
lines = read_temp_raw()
while lines[0].strip()[-3:] != 'YES':
time.sleep(0.2)
lines = read_temp_raw()
equals_pos = lines[1].find('t=')
if equals_pos != -1:
temp_string = lines[1][equals_pos+2:]
temp_c = float(temp_string) / 1000.0
return temp_c
def send_message(token, message):
url = 'https://{0}/devices/{1}/messages/events?api-version=2016-11-14'.format(URI, IOT_DEVICE_ID)
headers = {
"Content-Type": "application/json",
"Authorization": token
}
data = json.dumps(message)
print data
response = requests.post(url, data=data, headers=headers)
if __name__ == '__main__':
# 1. Enable Temperature Sensor
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')
# 2. Generate SAS Token
token = generate_sas_token()
# 3. Send Temperature to IoT Hub
while True:
temp = read_temp()
message = { "temp": str(temp) }
send_message(token, message)
time.sleep(1)

Step 5 - Power BI

Log on to Power BI.
Create a new dashboard.
Add two tiles.

Card

Click "Add tile" >> "Custom Streaming Data" >> "Next".
Select the temperatureDataset

Properties.

Visualization Type: Card
Fields: temp
Decimal Places: 2
Title: Temperature

Line Chart

Click Add tile.
Click Custom Streaming Data.
Click Next.
Select temperatureDataset.

Properties.

Visualization Type: Line chart
Axis: event_date
Values: temp
Time window: 1 minute
Title: Temperature (Celsius)

OUTPUT

Summary

Finally, we have successfully created a graph that streams the sensor data in real-time with IoT Hub using Powe BI.