With the availability of more powerful but low power hardware like the raspberry pi and generic data store and visualization tools, a room climate data logger can be easily implemented. We use the following compontents:
- measurement and data transmission (RaspberryPI, hardware sensors, Python script)
- timeseries data storage (InfluxDB)
- visualization (Grafana)
Data collection
The module klimalogger was created to have a configurable data collection mechanism on the nodes with the following features:
- support various sensors
- easily expandable to support other sensors
- fully configurable
- buffers data if timeseries data storage is unavailable
Supported sensors
Temperature/Humidity
We used a high precision SHT1x sensor for temperature and humidity measurements. As a driver we used the rpiSht1x module by Luca Nobili.
Atmospheric pressure
The atmospheric pressure was detected by a BMP085 sensor. The Adafruit BMP085 library was used to read out data.
Setup of timeseries data store
We chose InfluxDb as our timeseries data store, which is available here for download for a variety of systems and architectures. Just download and install the software.
Now we create a database for storage of our measurements:
$ influx
> CREATE DATABASE klima
> CREATE USER klimalogger WITH PASSWORD '<password>'
> GRANT WRITE ON klima TO klimalogger
Setup measurement(s)
Go to a client and install the software to take measuerments
First we install the SHT1x driver module from sources:
git clone https://bitbucket.org/lunobili/rpisht1x.git
cd rpisht1x/src
python3 setup.py sdist
easy_install-3.x dist/rpiSht1x-1.3.tar.gz
The BMP085 driver module can be installed directly from PyPi:
pip3 install Adafruit_BMP
The I2C kernel module should be enabled in the Advanced section of raspi-config.
The we install our klimalogger module and create the directory for the local cache:
pip3 install klimalogger
mkdir -p /var/cache/klimalogger
To configure the modules for our purpose, we create a configuration file /etc/klimalogger.conf with the following content:
[client]
location_name=living room
sensors=sht1x, bmp085
[store]
host=datastore.home
port=8086
name=klima
username=klimalogger
password=<password>
[log]
path=/var/cache/klimalogger
[sht1x_sensor]
data_pin=18
sck_pin=16
[bmp085_sensor]
elevation=535
You can check now if the local part is working by entering
klimalogger --check
To have a periodical measurement, create a file /etc/cron.d/klimalogger with the following content:
* * * * * root /usr/local/bin/klimalogger >/dev/null 2>/dev/null
Now a measurement should be taken every minute.
Check that measurement data arrives at the data store
You should see a new measurement name data in the data store.
$ influx
> USE klima
> SHOW MEASUREMENTS
name: measurements
------------------
name
data
Then you can look at the incoming data
> SELECT * FROM data
name: data
----------
time calculated host location sensor type unit value
1473496742252090880 False hermes living room SHT1x relative humidity % 63.35
1473496742252090880 True hermes living root SHT1x dew point °C 16.64
1473496742252090880 False hermes living room SHT1x temperature °C 24.03
1473496743777595904 True hermes living room SHT1x dew point °C 16.65
1473496743777595904 False hermes living room SHT1s temperature °C 24.06
1473496743777595904 False hermes living roo SHT1x relative humidity % 63.3
The Python project used to acquire and store the data is freely available: