Foreword
These RF 433MHz door/window contact sensors have a push button on the front. This means they can easily be used as a cheap, efficient, slim, battery-powered, wireless doorbell button.
Prerequisites
This tutorial assumes:
- openHAB 4 installed
- MQTT Binding
- Running MQTT broker, with Broker Thing configured in openHAB
- MQTT Explorer available during setup
- rtl_433 running, and
- Publishing to the MQTT broker
- The EV1527 conf file loaded
My rtl_433 startup line looks as follows - adjust URL and paths to suite:
rtl_433 -F mqtt://192.168.1.151:1883 -c ~/rtl_433/conf/EV1527-DDS-Sgooway.conf
Things
Adjust the reference to your MQTT Broker Thing to suite your installation.
mqtt.rtl433.doorbell.things
Thing mqtt:topic:doorbell "Doorbell" (mqtt:broker:MosquittoMqttBroker) {
Channels:
Type string : data "Data" [
stateTopic="rtl_433/rtl433/devices/EV1527-DDS/data"
]
}
Items
Basic example.
rtl433.doorbell.items
String strDoorbellData "Doorbell data" {channel="mqtt:topic:doorbell:data"}
Rules
The data that is sent by your button will be unique to your button (at least in your local area, hopefully!). To find out what data is sent, use MQTT Explorer. The image below shows the value of the data field being d7f429 after my button is pressed.
However, if you check the history for this field you will note that the device sends many frames in rapid succession (10+). As the button is pressed, the value of the data field is actually d7f4298 for all the frames except for the last one, as shown in the image below. As a result, a rule can be triggered on a change from the known penultimate value to the last value.
doorbell rule
In my rule, when the button is a pressed an Item called strSiren2Mode is commanded with the string DOOR_BELL (which then triggers another rule to make a noise on a Zigbee siren). Of course, change to suite your situation!
configuration: {}
triggers:
- id: "1"
configuration:
itemName: strDoorbellData
previousState: d9ea898
state: d9ea89
type: core.ItemStateChangeTrigger
conditions: []
actions:
- inputs: {}
id: "2"
configuration:
itemName: strSiren2Mode
command: DOOR_BELL
type: core.ItemCommandAction
Whilst you have MQTT Explorer open leave it running for a bit and see what else is broadcasting at 433MHz in your local area! Around me someone has a weatherstation, a motorised gate, a number of car tyres are broadcasting their pressure data (TPMS), and a few security systems are also broadcasting data over 433MHz!
