Weather Station

An application for recording weather from a MakerLife Raspberry Pi Zero W Weather Station kit and saving it to the console, a PostgreSQL database, or a CSV file.

The weather station kit includes the following sensors to be attached to a Raspberry Pi Zero W:

• A DS18S20 temperature sensor.
• A rainfall gauge.
• A wind meter.

Both the rainfall gauge and wind meter are simple switches that activate after a set amount of wind and/or rain.

Why?

The example project provided by MakerLife was only in Python and only displayed output to the terminal (and only in metric units). I wanted something that could start a little faster and would record to a PostgreSQL database so I could use the historical data later.

I also wanted an application that could record to a remote database so I could mount the SD card as read only to prevent wearing out the SD card.

Configuring

The application is split out into several different "recorders" that can be used to send data to different endpoints. You can enable all recorders by doing the following:

make USE_PGSQL=1 USE_CSV=1 USE_REST=1 USE_IMPERIAL=1

If USE_PGSQL is 1 the application will be configured to connect to a PostgreSQL database (see below) to insert samples at fixed intervals into a table. This requires libpq-dev.

If USE_IMPERIAL is 1 the units will be set to imperial units instead of metric.

If USE_CSV is 1 the application will output a CSV file.

In the recorder_pgsql.c file the following configuration options are available:

#define PGSQL_CONNECT_STRING "host=localhost dbname=weather user=weather password=password"
#define CSV_FILE "weather.csv"
#define TEMP_SAMPLE_RATE 5
#define SAMPLE_RATE 60

Change the PGSQL_CONNECT_STRING to connect to your database. The syntax for this string can be found here.

An example table for PostgreSQL can be found in weather.sql.

Change CSV_FILE in recorder_csv.c to change the name/path of the generated CSV file.

Change TEMP_SAMPLE_RATE to change the rate in seconds at which the temperature sensor is polled.

Change SAMPLE_RATE to change the rate in seconds at which the samples are sent to the terminal and/or the database and/or the CSV file.

If USE_REST is 1 then the application will attempt to send a JSON encoded REST POST to the endpoint REST_ENDPOINT in recorder_rest.c.

Compiling

To compile this project you'll need the following packages (Raspbian):

sudo apt install build-essential wiringpi libpq-dev

Note: libpq-dev is only required if you want to save to a PostgreSQL database (see above).

In order for the temperature sensor to work you'll also need to make sure you enable the 1-wire kernel module.

To make the application:

make

To run the application:

./weather

The application should now send samples to the terminal and any other configured destinations at fixed intervals:

Weather Measurements:
     Start: 2018-10-23 21:54:16
       End: 2018-10-23 21:55:15
  Duration: 59 seconds
      Temp: 42.180801 f
      Wind: 1.037264 mph (83 ticks)
      Rain: 0.000000 inches (0 tips)

Writing your own Recorder

If you want to write your own recorder to send weather data to a custom endpoint you can do that by creating a new file (for example recorder_example.c) like this:

#include "weather.h"

void record_example(char* start, char* end, float temp, float wind, int spins, float rain, int tips) {
    //Do your custom recording here.
}

/**
* Register ourselves with the plugin system.
*/
RECORDER_INIT(EXAMPLE) {
    add_recorder("example", &record_example);
}

Then add the following to Makefile:

ifeq ($(USE_EXAMPLE), 1)
    OBJ += recorder_example.o
endif

Then make by doing the following:

make USE_EXAMPLE=1