README.md

Maplins switch

Some of the code I've hacked together while playing with the Maplin remote switches and my Raspberry Pi.

maplin-mqtt.py

This is the main script, it is designed to connect to MQTT and wait for messages requesting a switch is turned on or off. It is designed to configure itself to know about all possible switches. It does this by connecting to a topic on MQTT, where it expects to find a JSON document which defines all switches. The format of that JSON document should be as shown below:

{
    "rooms": {
        "Tank": {
            "channel": 4,
            "button": 2
        },
        "Living Room": {
            "channel": 4,
            "button": 1
        }
}

It can contain as many switches as you like.

The format of messages it expects to receive is:

'{"action": "off", "switch": "spareroom"}'

The value of switch must match one of the rooms defined in the configuration JSON document.

The script is designed to be run as a daemon, from supervisorD or something similar, as a result it logs to standard out, expecting something else to rotate those logs.

Configuration

Takes the following mandatory environment variables:

• MQTT_HOST Host to connect to
• MQTT_TOPIC MQTT the base topic to subscribe to, see note below.

And also takes the following optional variables

• MQTT_USERNAME MQTT Username for the connection
• MQTT_PASSWORD MQTT Password for the connection

MQTT Topic note

The script actually uses two topics on the broker, as a result, the topic defined in the MQTT_TOPIC environment variable is actually the base topic (which must end in a trailing forward slash). It then connects to two topics under that:

• MQTT_TOPIC/switches - This is the topic where it expects to find the configuration JSON.
• MQTT_TOPIC/toggle - This is the topic where it listens for requests to turn switches on or off.