Remotely monitor the sensed temperature, humidity using DHT11 and also remotely control the fan (DC motor) speed using L293D.

Requirements

• Raspberry Pi
• PHP + MYSQL for website
• Python
• DHT11 for temperature, humidity
• L293D to control DC motor speed.

Installation

1. Make connections. You can make them as per the links provided in references.
2. Modify pin numbers utilized in rpi.py, only if needed.
3. site folder contains website code, deploy it and change the related URLs declared as http://localhost/site/ in rpi.py, if needed.
4. Import site/iot.sql to setup database and it's tables with dummy data.
5. Update database credentials declared in site/api/database.php.
6. Run rpi.py

Usage and Screenshots

1. Home page: site/index.html

2. Show captured humidity, temperature: site/data.html

3. The graph on the same page, for comparison of humidity, temperature with reference to time.

4. Display previous automatic setting parameters and change them: site/settings.html

5. Display previous manual settings and change it, the same page.

6. What is Auto & Manual Setting?

   Auto takes 3 input pairs:

   • Low humidity-temperature (x1,y1)
   • Medium humidity-temperature (x2,y2)
   • High humidity-temperature (x3,y3)

   Compares these 3 input pairs with currently sensed Humidity-Temperature (x,y) pair by using a modified form of Distance Formula in order to decide the speed of the fan: low, medium or high speed.

   Example, if the distance is (x,y) and (x1,y1) is the lowest, then speed must be low.

   Manual takes one single input out of:

   • Low
   • Medium
   • High
   • None

   If None is set, then it utilizes the latest auto setting parameters to decide the speed of the fan, otherwise, the Manual setting is considered over Auto Setting.

7. When you execute rpi.py

How does the raspberry-pi code work

When you execute rpi.py, we fetch the manual setting from site/api/manual.php. If manual setting is set, we sense the temp-humidity but set the fan speed as per manual choice, and send the sensed temperature-humidity to site/api/data.php. If manual setting is not present or it is None, we fetch the latest auto setting parameters from sit/api/auto.php, then sense the temp-humidity and use Distance Formula (as previously explained) to set the fan speed and then send the sensed temp-humidity to site/api/data.php. This cycle repeats every 5 seconds as defined in rpi.py inside start function.

How does the website work

Webapp is used to remotely displayed all the sensed temp-humidity record, graph and all the settings previously defined. User can redefine auto/manual setting. It also contains the api endpoints defined in api/* files which is used to communicate between database, frontend and python, for:

• Fetching all the previous records of temperature-humidity
• Fetching all the previous records of settings (auto/manual)
• Set auto setting
• Set manual setting
• Truncate all previous records
• Delete all manual settings
• Delete all auto settings except latest one.

References

• DHT11
• DC Motor Control using L293D - 1
• DC Motor Control using L293D - 2