thermohygrometer

Read temperature and humidity from DHT11 sensor and save its history to SQLite3 database on Raspberry Pi. The thermohygrometer is four main things below.

• UI: UI component that shows temperature and humidity chart.
• Collector: Read measured data from DHT11 via GPIO and save it into SQLite3 database.
• Server: API Server to retrieve temperature and humidity history.
• SQLite3: As a database.

Installation

Clone and build on Raspberry Pi that you wanna run it on.

UI

npm install
npm run build
THERMOHYGROMETER_API_URL=http://<Server IP>:<API Port> THERMOHYGROMETER_UI_PORT=<UI App Port> npm start

SQLite3 database

Prepare SQLite3 database before running collector and server. Run sqlite3 command then create a table and an index to initialize database.

sqlite3 /path/to/sensor.db

CREATE TABLE temperature_and_humidity (id integer primary key, temperature real not null, humidity real not null, unixtimestamp integer not null);
CREATE INDEX idx_unixtimestamp on temperature_and_humidity (unixtimestamp);

Collector

NOTE: Run as root to access GPIO.

cd thermohygrometer/cmd/collector
go build
sudo ./collector -gpio 14 -db /path/to/sensor.db -interval 10s

• -gpio: The GPIO input-pin number.
• -db: Path to the SQLite3 database.
• -interval: Data collection intervals.

Server

cd thermohygrometer/cmd/server
go build
server -host 0.0.0.0 -port 8000 -db /path/to/sensor.db

• -host: Listen IP address.
• -port: Listen port.
• -db: Path to the SQLite3 database.

Server API

GET /current

Get the latest temperature and humidity from database.

Example

{
    "temperature":22,
    "humidity":15,
    "timestamp":"2021-01-10T13:25:48Z"
}

GET /histories

Get temperature and humidity history in the range of given parameters.

• parameters
  • before: RFC3339 format (ex: 2021-01-10T13:28:00.337Z)
  • interval: millisecond
  • count: The number of data

Example

The followings shows the response of /histories?before=2021-02-09T03:54:13Z&interval=3600000&count=12. It gets 12 pieces of temperature and humidity data, one per every 3600000 millisecond (1 hour) interval before and at 2021-02-09 03:54:13 UTC.

{
    "pages": {
        "total": 12
    },
    "data": [
        {
            "temperature": 23,
            "humidity": 12,
            "timestamp": "2021-02-09T15:54:13Z"
        },
        {
            "temperature": 22,
            "humidity": 12,
            "timestamp": "2021-02-09T14:54:06Z"
        },
        {
            "temperature": 25,
            "humidity": 6,
            "timestamp": "2021-02-09T13:52:13Z"
        },
        {
            "temperature": 24,
            "humidity": 13,
            "timestamp": "2021-02-09T12:54:11Z"
        },
        {
            "temperature": 21,
            "humidity": 12,
            "timestamp": "2021-02-09T11:54:13Z"
        },
        {
            "temperature": 23,
            "humidity": 15,
            "timestamp": "2021-02-09T10:54:13Z"
        },
        {
            "temperature": 23,
            "humidity": 12,
            "timestamp": "2021-02-09T09:53:53Z"
        },
        {
            "temperature": 24,
            "humidity": 3,
            "timestamp": "2021-02-09T08:53:35Z"
        },
        {
            "temperature": 23,
            "humidity": 5,
            "timestamp": "2021-02-09T07:54:06Z"
        },
        {
            "temperature": 24,
            "humidity": 5,
            "timestamp": "2021-02-09T06:53:51Z"
        },
        {
            "temperature": 26,
            "humidity": 4,
            "timestamp": "2021-02-09T05:54:16Z"
        },
        {
            "temperature": 24,
            "humidity": 5,
            "timestamp": "2021-02-09T04:54:16Z"
        }
    ]
}

License

MIT