This is a monitoring system for air parameters (like temperature or humidity) and activity of the sun. The main goal is to run this software on Raspberry Pi Zero or similar small computer with small amount of hardware and low power consumption.

The data can come from external sensors connected to WiFi network by devices (e.g. ESP8266 devices family).

The first layer contains IoT RESTful server based on Flask REST JSON:API and SQLite database which stores data that come from external sensors. The second layer is a set of scripts for converting data from SQLite database to RRDTool databases and generating set of time based graphs. These graphs are shown in the third layer on html site served by lighttpd server.

If you have more powerful computer you can use Grafana or similar software to show nice graphs with some metrics. Below I described how to install this on Raspberry OS system.

Sunny day without clouds.

You can see sunny and cloudy days.

• Raspberry OS
• SQLite
• RRDTool
• Sunwait
• some HTTP server, e.g. Lighttpd

• this ZeroIoT server for grabbing and collecting IoT data in simple SQLite database.
• lightweight HTTP server for serving static files like graphs with IoT metrics, e.g. Lighttpd.
• RRDTool for storing time based series of IoT data and generating graphs mentioned above.

For marking day and night on the grahps.

git clone https://github.com/risacher/sunwait
cd sunwait
make
sudo mv sunwait /usr/bin/

sudo apt install sqlite3
sudo apt install lighttpd
sudo apt install rrdtool librrd-dev python3-dev
git clone https://github.com/pkoscielny/zeroiot
cd zeroiot
sudo cp /etc/lighttpd/lighttpd.conf /etc/lighttpd/lighttpd.conf_bak
sudo bash -c 'cat configs/lighttpd.conf > /etc/lighttpd/lighttpd.conf'

Open /etc/lighttpd/lighttpd.conf with root rights and set absolute path to rrdtool dir in server.document-root and restart server:

sudo systemctl restart lighttpd
sudo systemctl status lighttpd

Set up configuration file and change some configurations as you want:

cp configs/config.ini_example configs/config.ini 

You can run zeroiot step by step or run it in Docker container (please see comments in configs/Dockerfile) Step by step version:

sudo apt install python3-venv
python3 -m venv ./venv
source venv/bin/activate
pip install -r configs/requirements.txt
./venv/bin/gunicorn --bind :3000 -w 1 app.main:app

Check if Gunicorn works properly:

curl http://localhost:3000/air_state

If works then add this server to systemd as a service:

sudo cp configs/zeroiot.service /etc/systemd/system/ 

Set correct paths in /etc/systemd/system/zeroiot.service and run:

sudo systemctl daemon-reload
sudo systemctl start zeroiot
sudo systemctl status zeroiot
sudo systemctl enable zeroiot

Try to ask ZeroIoT server: http://localhost:3000/air_state

By default Gunicorn has turned off logging and this is what I expected on production environment (vitality of microSD card). You can observe logs from this service here:

sudo journalctl -u zeroiot.service

Try to run scripts for updating RRD databases and generating graphs:

./venv/bin/python tools/update_rrd_db.py 
./venv/bin/python tools/generate_rrd_graphs.py  

If these work fine with no errors add these to crontab:

*/5 * * * * bash -c 'cd /path/to/your/zeroiot && ./venv/bin/python tools/update_rrd_db.py > /dev/null && ./venv/bin/python tools/generate_rrd_graphs.py > /dev/null'

For debugging you can send output to file, e.g: bash -c '.... > /tmp/zeroiot.log 2>&1' and observe this:

watch -n1 cat /tmp/zeroiot.log

Add some data using ZeroIoT. For testing you can add some mocked data using crontab:

* * * * * bash -c "curl 'http://localhost:3000/insolation' -H 'Content-Type: application/vnd.api+json' --data-raw '{\"data\":{\"type\":\"insolation\",\"attributes\":{\"insolation\":`shuf -i 700-800 -n 1`,\"device\":\"esp8266_nodemcu_v2\"}}}'"
* * * * * bash -c "curl 'http://localhost:3000/air_state' -H 'Content-Type: application/vnd.api+json' --data-raw '{\"data\":{\"type\":\"air_state\",\"attributes\":{\"temperature\":`shuf -i 18-23 -n 1`,\"humidity\":`shuf -i 40-60 -n 1`,\"device\":\"esp-01S_1\",\"location\":\"kitchen\"}}}'"
* * * * * bash -c "curl 'http://localhost:3000/air_state' -H 'Content-Type: application/vnd.api+json' --data-raw '{\"data\":{\"type\":\"air_state\",\"attributes\":{\"temperature\":`shuf -i 18-23 -n 1`,\"humidity\":`shuf -i 40-60 -n 1`,\"device\":\"esp-01S_2\",\"location\":\"bathroom\"}}}'"
* * * * * bash -c "curl 'http://localhost:3000/air_state' -H 'Content-Type: application/vnd.api+json' --data-raw '{\"data\":{\"type\":\"air_state\",\"attributes\":{\"temperature\":`shuf -i 18-23 -n 1`,\"humidity\":`shuf -i 40-60 -n 1`,\"device\":\"esp-01S_3\",\"location\":\"big_room\"}}}'"
* * * * * bash -c "curl 'http://localhost:3000/air_state' -H 'Content-Type: application/vnd.api+json' --data-raw '{\"data\":{\"type\":\"air_state\",\"attributes\":{\"temperature\":`shuf -i 18-23 -n 1`,\"humidity\":`shuf -i 40-60 -n 1`,\"device\":\"esp-01S_4\",\"location\":\"small_room\"}}}'"

After 5 minutes you should see new files in rrdtool dir and everything on site http://localhost.

If you want to remove the data completely from your ZeroIoT system you can do it this way:

cd path/to/your/zeroiot
sudo systemctl stop zeroiot.service
rm iot.db
rm rrdtool/*.rrd
sudo systemctl start zeroiot.service

Run server in dev mode:

FLASK_APP="app:create_app('dev')" FLASK_ENV="development" ./venv/bin/python -m flask run --port=3000

These are two main resources with their attributes:

• air state
  • temperature (float)
  • humidity (float)
  • location (string)
  • device (string)
• insolation
  • insolation (int)
  • device (string)

Table of resources:

Probably you will only need to add new items or show list of items. Below you can see examples.

This data can come from sensor based on photoresistor. You can easily save the state of the sun activity. It affects the state of the air inside. In a cloudy day these values will be significantly lower. Send this data to ZeroIoT server.

Request:

POST /insolation HTTP/1.1
Content-Type: application/vnd.api+json
Accept: application/vnd.api+json

{
  "data": {
    "type": "insolation",
    "attributes": {
      "insolation": 230,
      "device": "esp8266_nodemcu_v2"
    }
  }
}

Response:

HTTP/1.1 201 Created
Content-Type: application/vnd.api+json

{
  "data": {
    "type": "insolation",
    "id": "2",
    "attributes": {
      "created": "2021-03-07 09:01:02",
      "insolation": 230,
      "device": "esp8266_nodemcu_v2"
    },
    "links": {
      "self": "/insolation/2"
    }
  },
  "links": {
    "self": "/insolation/2"
  },
  "jsonapi": {
    "version": "1.0"
  }
}

Request:

GET /insolation HTTP/1.1
Accept: application/vnd.api+json

Response:

HTTP/1.1 200
Content-Type: application/vnd.api+json

{
  "data": [
    {
      "type": "insolation",
      "attributes": {
        "created": "2021-03-07 09:00:35",
        "insolation": 123,
        "device": "esp8266_nodemcu_v2"
      },
      "id": "1",
      "links": {
        "self": "/insolation/1"
      }
    },
    {
      "type": "insolation",
      "attributes": {
        "created": "2021-03-07 09:01:02",
        "insolation": 230,
        "device": "esp8266_nodemcu_v2"
      },
      "id": "2",
      "links": {
        "self": "/insolation/2"
      }
    }
  ],
  "links": {
    "self": "http://localhost:3000/insolation"
  },
  "meta": {
    "count": 2
  },
  "jsonapi": {
    "version": "1.0"
  }
}

Many sensors can provide the temperature and the humidity values. I recommend to use better quality sensors like DHT21 or better. Send this data to ZeroIoT server.

Request:

POST /air_state HTTP/1.1
Content-Type: application/vnd.api+json
Accept: application/vnd.api+json

{
  "data": {
    "type": "air_state",
    "attributes": {
      "temperature": 24.1,
      "humidity": 65.4,
      "location": "bathroom",
      "device": "esp8266_dev1"
    }
  }
}

Response:

HTTP/1.1 201 Created
Content-Type: application/vnd.api+json

{
  "data": {
    "type": "air_state",
    "attributes": {
      "temperature": "24.1",
      "location": "bathroom",
      "created": "2021-03-07 14:46:37",
      "device": "esp8266_dev1",
      "humidity": "65.4"
    },
    "id": "2",
    "links": {
      "self": "/air_state/2"
    }
  },
  "links": {
    "self": "/air_state/2"
  },
  "jsonapi": {
    "version": "1.0"
  }
}

Request:

GET /air_state HTTP/1.1
Accept: application/vnd.api+json

Response:

HTTP/1.1 200
Content-Type: application/vnd.api+json

{
  "data": [
    {
      "type": "air_state",
      "attributes": {
        "temperature": "23.2",
        "location": "kitchen",
        "created": "2021-03-07 14:45:24",
        "device": "esp8266_dev2",
        "humidity": "56.3"
      },
      "id": "1",
      "links": {
        "self": "/air_state/1"
      }
    },
    {
      "type": "air_state",
      "attributes": {
        "temperature": "24.1",
        "location": "bathroom",
        "created": "2021-03-07 14:46:37",
        "device": "esp8266_dev1",
        "humidity": "65.4"
      },
      "id": "2",
      "links": {
        "self": "/air_state/2"
      }
    }
  ],
  "links": {
    "self": "http://localhost:3000/air_state"
  },
  "meta": {
    "count": 2
  },
  "jsonapi": {
    "version": "1.0"
  }
}

For updating and deleting the data you can also use standard JSON:API syntax (https://jsonapi.org/).

Enjoy!