1-wire, Node-Red, Domoticz & Grafana

Recently I posted a shiny graph of my garage temperature after I’d put a car with a hot engine in there. The spikes were fairly pronounced, and it was possibly to see where I’d left the door open whilst I worked on the car, before going for a test drive in the evening.

I was subsequently asked…

tl;dr 1-Wire -> ESP8266 -> MQTT -> Node-Red -> MQTT -> Domoticz -> MQTT -> Node-Red -> InfluxDB -> Grafana

It starts out simply enough, with a string of DS18B20 1-wire sensors hooked up to a WeMos D1 Mini NodeMCU board. On that board, there’s a copy of https://github.com/kylegordon/mqtt_esp8266_ds1820_arduino flashed onto, and it scans the bus periodically, reads the values, and publishes them to an MQTT broker. Each ROM ID (1-wire device) gets its own topic, and a plain number is published to the relevant topic.

My home automation controller of choice is Domoticz , and it likes a particular flavour of JSON being published on the /domoticz/in topic. This is where Node-Red steps in to do a translation.

[{“id”:”aa0d4469.8e7458″,”type”:”mqtt in”,”z”:”d5caab33.2a3558″,”name”:”esp8266 on temp/#”,”topic”:”temp/#”,”qos”:”2″,”broker”:”66a92c76.9956d4″,”x”:117,”y”:349,”wires”:[[“5f4ec201.7bbdac”]]},{“id”:”5f4ec201.7bbdac”,”type”:”function”,”z”:”d5caab33.2a3558″,”name”:”Device to IDX”,”func”:”temp = msg.payload/16;\nrom_id = msg.topic.split(\”/\”)[1];\n\nmsg.payload = {};\nswitch (rom_id) {\n case \”28b8c81d300e5\”:\n msg.payload.idx = 186;\n break;\n case \”28ac871d300e4\”:\n msg.payload.idx = 187;\n break;\n}\nmsg.payload.rom_id = rom_id;\ntemp = temp.toString();\nmsg.payload.svalue = temp;\n\n\nreturn msg;”,”outputs”:1,”noerr”:0,”x”:347,”y”:348,”wires”:[[“71da0e3.d7e8ff”]]},{“id”:”71da0e3.d7e8ff”,”type”:”mqtt out”,”z”:”d5caab33.2a3558″,”name”:””,”topic”:”domoticz/in”,”qos”:””,”retain”:””,”broker”:”66a92c76.9956d4″,”x”:535,”y”:349,”wires”:[]},{“id”:”66a92c76.9956d4″,”type”:”mqtt-broker”,”z”:””,”broker”:”homeauto.vpn.glasgownet.com”,”port”:”1883″,”clientid”:””,”usetls”:false,”compatmode”:true,”keepalive”:”15″,”cleansession”:true,”willTopic”:””,”willQos”:”0″,”willPayload”:””,”birthTopic”:””,”birthQos”:”0″,”birthPayload”:””}]

In short, this flow subscribes to all messages on temp/#, takes the payload and topic, and formulates a JSON message with the correct IDX. The IDX is the unique ID for a virtual device (in this case, a temperature sensor) in Domoticz. The JSON message is then published on /domoticz/in, where it is consumed by Domoticz and used for its own home automation purposes.

Now, every value of every device in Domoticz is also published on /domoticz/out. I use this for a few MQTT to Python services I run, but I also have another Node-Red flow that takes the Domoticz JSON messages and inserts them into InfluxDB. This flow was taken from here and relies on the node-red-contrib-influxdb node.

The rest is plain sailing really – there’s a Grafana install that is configured to use InfluxDB as a datasource. Grafana can extract the data using the IDX that’s mentioned above, and will display it in a nice fashion.

SELECT mean(“svalue1”) FROM “domoticz” WHERE “idx” = ‘171’ AND $timeFilter GROUP BY time($interval) fill(null)

Job done.

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