ESP8266 433/315Mhz MQTT over WiFi bridge

This MQTT bridge allows you to control cheap home-automation RF power outlets using a common MQTT interface. With e.g. Home-assistant, these power outlets can then be switched on/off remotely over the internet and integrate seamlessly with IFTT.

MQTT auto-discovery

The MQTT broker is automatically discovered through mDNS. When you do not want to use this, simply put the static IP or hostname of your MQTT broker in the hostString variable.

To enable MQTT discovery on the broker, simply install avahi-daemon. For a Raspberry Pi, use the following command:

sudo apt-get install avahi-daemon

Next, create the following service declaration in /etc/avahi/services/mqtt.service:

<service-group>
  <name replace-wildcards="yes">MQTT on %h</name>
  <service>
    <type>_mqtt._tcp</type>
    <port>1883</port>
  </service>
</service-group>

Restart your avahi-daemon service: sudo service avahi-daemon restart.

Please note that discovery over mDNS only works within the same multicast/broadcast domain and cannot cross network interfaces, unless a mDNS-repeater or igmp-proxy is used.

MQTT protocol

The following MQTT payload should be sent:

• Topic: /switch/rf/[ID]
  • e.g. /switch/rf/5
• Payload: [protocol]|[pulselength]|[binary code]
  • e.g. 4|101|101010100100101100101100

These protocol, pulselength and binary variables can be sniffed as described in Obtaining RF codes.

For persistency, the retain-flag can be set such that the codes are re-sent when the ESP8266 is rebooted.

Code setup

• Get the Arduino ESP8266 firmware. For install instructions please check here.
• Install the Arduino RC-switch library
• Install the Arduino PubSubClient library
• Configure your wireless password in the WIFI_SSID and WIFI_PASSWORD variables

Wiring

The firmware was tested on a NodeMCU development board. The 433/315 transmitter data pin was connected to D2 pin (GPIO4), but any other gpio can be used. Most transmitters can be powered using 3.3V directly.

Obtaining RF codes

The RF codes can be sniffed using the RC-switch examples using an Arduino or ESP8266 as well. Keep in mind that there might be a difference measured in pulselength depending on the device, since rc-switch (currently) does not adjust for clock speed. It is therefore advisable to also use an ESP8266 when sniffing the codes.

Home Assistant example

Example configuration in Home Assistant

# Broker config
mqtt:
  broker: 127.0.0.1
  port: 1883
  client_id: home-assistant-1
  keepalive: 60

# RF switch
switch:
  - platform: mqtt
    name: "Bedroom light"
    command_topic: "switch/rf/1"
    payload_on: "4|101|101000110001100001101100"
    payload_off: "4|101|101010100100101100101100"
    optimistic: false
    qos: 0
    retain: true

License

The code falls under the MIT license.