Raspberry Pi Web Thermostat

Dependencies

• CrowCpp
• WiringPi
• Boost
• Json
• SHA256

Building

You first need to install boost with sudo apt install build-essential libboost-all-dev after that add dtoverlay=i2c-sensor,bmp280 to /boot/config.txt (this enables the system module for the BMP280 sensor) then make

If you wish to make it more permanent use sudo make install this will move the build folder into /opt/RPIThermostat and it will also move libwiringPi.so and RPIThermostat.service to /usr/lib and /etc/systemd/system/. Then you can use systemctl to start/stop/enable/disable the service

Build Folder Structure

    build/
        static/
            css, javascript, etc
        templates/
            .html pages

        config.json
        parameters.json
        site

Configuration Files

There are two files:

• config.json
• parameters.json

Config.json

This file contains all the parameters required to start the app. Default:

{
    "site":{
        "port": 18080,
        "password": "password",
        "cookieLifetime": 20,
        "cleanInterval": 3600
    },

    "controller":{
        "numOfReads":1,
        "readDelay":7000,
        "calibration":-2,
        "driverFile":"sys/bus/iio/devices/iio:device0/in_temp_input",
        "relayPin":3,
        "saveInterval": 600,
        "display":{
            "digits":[12,16,20,21],
            "A":26,
            "B":13,
            "C":9,
            "D":5,
            "E":6,
            "F":19,
            "G":10,
            "DP":11
        }
    }
   
}

Tags

• site settings related to the site
  • port is the port on which the webserver runs
  • password password for site access (this gets hashed)
  • cookieLifetime this determines the lifetime of the authentification tokens both server and client side
  • cleanInterval the amount of time at which the program cleans expired cookies from memory
• controller settings related to the phyisical part of the thermostat
  • numOfReads determines how many temperature readings the program makes and averages them
  • readDelay the delay between temperature readings
  • calibration offsets the read temperatures by the specified value
  • driverFile path to BMP280 input file
  • saveInterval the amount of time at which the program saves the internal threshold and range to disk
  • display
    • digits pins responsible for each digit segment in the display in order
    • A,B,C,D,E,F,G,DP pins responsible for each segment of the 7 segment display

Parameters.json

This file is used to store the operating range of the thermostat.

{
    "minTemp": 29,
    "maxTemp":0.3
}

This file is updated every 10 minutes by the program with the values from memory.

Site Endpoints

The main endpoints of the site are:

• / login page (if a login cookie is already present it redirects to /dashboard)

• /auth recieves form POSTrequests from / with the hashed password and if the hash is correct it returns a cookie with a lifetime specified in the config.json file

• /dashboard the main page where the operating parameters can be set and information about the current temperature and current state can be seen. Also if there is no authentification cookie it redirects to /

• /getParams if a authentification cookie is present it returns a json object containing the current temperature, state, threshold and range

• /setParams recieves POST requests with json objects that contain the new threshold and range and it sets those parameters to the recieved ones

• /shutdown issues shutdown command to the system sudo system -P now

• /temperature get temperature related data from the database. Example: /temperature/get/2021-01-01 returns all temperature from the specified date untill the present day

• /state same as with the temperature endpoint

By default in CrowCpp every file in build/static/ can be accessed through /static/file

Site aspect

You can replace the scripts, html and css files with your own and make it look good