MQTT and RRDTool

I mentioned in one of my earlier posts that Xively was nice as a quick test setup, but in the end I would like to have my data locally.

To this end I have installed Mosquitto as an MQTT server on a spare Linux machine in the office.  I changed the nRF receiver Arduino to send the sensor data to topics in Mosquitto. I used the PubSubClient for the MQTT connection.

The format of the topics are

“/sensors/radio/<device-id>/<sensor-number>/<type>”

device-id is the address of the remote sensor device

sensor-number is the sensor on the device 1, 2, 3 … etc

type is the type of the sensor temperature, light, battery, etc

This is working as expected, but the data is more or less thrown away unless we have something to subscribe to it!

So on the subscription side i wanted something up and running quick, so I found this snippet of perl code that subscribes to a topic extracts data from the message content and updates an RRD database. For the moment it just does the temperature data.

I then have a script that runs every so often to create some graphs from the rrd data.

The results can be seen here.

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