13. IoT Case 10: Home Health Data Monitoring

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13.1. Goal

Make a home health data monitoring system by collecting data from the sensors inside the house. Also use the temperature and humidity value to calculate the IAQ Score as reference.

13.2. Background

What is home health data monitoring system?

Health monitoring is the concept of tracking the conditions of different parameters inside the user’s house. For indoor, the important parameters to analyze the home comfortability are temperature, humidity, pm2.5, CO2 and VOC. In this system, we can base on temperature and humidity to measure the comfortability of the home. With the too high temperature or too low humidity will also affect the comfortability.

Home health monitoring system Principle

In this case, integrated temperature and humidity sensor DHT11 is used. It will keep track of room temperature, humidity and IAQ value, display to the OLED and upload to the Thingspeak platform for further analysis.

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Know more: What is an IAQ?

Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. Understanding and controlling common pollutants indoors can help reduce your risk of indoor health concerns. The important parameters are temperature, humidity, pm2.5, CO2 and VOC.

Know more: How to determine the IAQ Score?

In Smarthon Smart Home IoT Maker Kit, we use 2 parameters (temperature and humidity) to determine the comfortability (IAQ Score) of the room. Below is the chart to show most comfortable value of temperature (20-22) with humidity (40-70). auto_fit

Therefore, better range of temperature will have higher score of IAQ; Better range of humidity will have higher score of IAQ. Thus, the average value of IAQ score from temperature and humidity can determine the comfortability of the room. In other words, for the used of block on pxt from Smarthon, it will return the average value of temperature and humidity IAQ score.

13.3. Part List

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13.4. Assembly step

Step 1

In this case, “Open Style Model” is used as a home base to start with.

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Step 2

Put the model E4 & E1 onto model A, align with holes at model A, B2 and B3.

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Step 3

Attach the OLED display onto model E4 using M4 * 10mm screws and nuts.

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Step 4

Attach the DHT11 temperature and humidity sensor onto model E4 using M2 * 10mm screws and nuts. And the connecting wire should be bended to the hole below it.

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Step 5

To build a sofa model. Put the model K3 to the two sides of model K1.

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Step 6

Put model K2 all together to the cardboard parts (K1-K3).

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Step 7

Plase the sofa model behind the model E4.

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Step 8

Assembly Completed!

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13.5. Hardware connect

  1. Connect the temperature and humidity sensor DHT11 to P0

  2. Pull up the buzzer switch to disconnect the buzzer

  3. Connect the OLED display to IoT:bit I2C port with extend cable

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13.6. IoT (Thingspeak)

Step 1. Create Thingspeak channel

  • Go the Thingspeak create an account and create a channel pic_90

Step 2. Get channel API

  • After created a new channel, get the write in API pic_90

13.7. Programming (MakeCode)

Step 1. Initialize OLED, IoT:bit and connect to WiFi, create and initialize variables

  • Snap Initialize OLED with width:128, height: 64 to on start

  • Snap Initialize IoT:bit TX P16 RX P8 from IoT:bit to on start

  • Snap Set WiFi to ssid smarthon pwd 12345678 to on start

  • Create and initialize the variables temperature, humidity and iaq_score to 0 auto_fit

Step 2. Show icon “tick” after WiFi connection

  • In On WiFi connected, put a show icon tick get notice after WiFi is connected. pic_60

Step 3. Create the function check_condtion

  • Create a new function check_condition

  • Put nested if-else statement inside the function

  • The first condition is iaq_score < 20, then show string Very uncomfortable in the segment

  • The second condition is iaq_score < 40, then show string Uncomfortable in the segment

  • The third condition is iaq_score < 60, then show string Discomfortable in the segment

  • The fourth condition is iaq_score < 80, then show string Comfortable in the segment

  • The fifth condition is iaq_score <= 100, then show string Very comfortable in the segment

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Step 4. Read the Temperature and Humidity sensor data

  • In Forever, put a if statement with condition WiFi connected? to make sure connected to interent before uploading to thingspeak

  • Use Read Temperature & Humidity sensor at pin P0 to read the data from DHT11 Temperature and Humidity Sensor

  • After read the DHT11 data, use the three functions to get the result and set to the variable

  1. Set temperature to Get Temperature °C for temperature

  2. Set humidity to Get Humidity for humidity

  3. Set iaq_score to Get IAQ Score for iaq_score auto_fit

Step 4. Show the data on display

  • Clear the display before each times update by clear OLED display

  • Show the three variables respectively, with some text explanation

  1. show string join Temperature: temperature for temperature

  2. show string join Humidity: humidity % for humidity

  3. show string Join IAQ Score: iaq_score for iaq_score auto_fit

Step 5. Analyst the environment status

  • Run the check_condition function to summarize the IAQ Score result

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Step 6. Upload to Thingspeak

  • Send the data to Thingspeak by Send Thingspeak key XXXX field1 value XXX ..., fill in the write API key from the Thingspeak channel and the values need to be upload

  • After uploading the data to Thingspeak, wait for 15 second to avoid upload too frequently by pause(ms) 15000, then start another Reading and uploading.

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Step 7. Check Thingspeak upload status

  • To check the uploading status, use On thingspeak Uploaded to get the uploading result

  • Insert newline for better visual effect

  • Use the Status and Error_code from block placeholder respectively to showing some text explanation

  1. show string join Thingseak: Status for Upload status

  2. show string join Error: Error_code for Error code if upload failed

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Full Solution

MakeCode: https://makecode.microbit.org/_Vw1ebpiE2CsR

You could also download the program from the following website:

13.8. Result

The OLED show the temperature, humidity, IAQ Score and the environment condition based on IAQ Score. After upload, show the uploading information

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13.9. Think

  1. Apart from temperature and humidity, what elements do you think are essential to be included in a home health monitoring system? (E.G CO2 level? PM2.5 value?)

  2. What function do you think the system can also include if it is to be used in a real home? (E.G Alert when the condition is too bad for health?)