All our systems will talk will talk fluently MQTT. MQTT is based on a 'publish & subscribe' mechanism.
The controller needs to send data to our database & needs to receive commands from higher systems.
| Topic | Value | MQTT task | Comment |
|---|---|---|---|
| controllers/#macaddress#/input | #line_protocol# | publish | All things that need to be stored to the database: button presses, diagnostics, ... |
| controllers/#macaddress#/output | #json object# | subscribe | All things that a specific controller needs to do: light up buttons, print text, ... |
| controllers/#macaddress#/im_alive | #line_protocol# | publish/last will | All things regarding onboarding and offboarding: on first connect an "I'm alive" message can be send, on connection lost, the broker can send a specific "I'm dead" message. |
| controllers/output | #json object# | subscribe | All things that all controllers need to do: * Send a diagnostics string (battery level, uptime, connected bssid) * |
The input topic and I'm alive topic need to follow the line protocol so that these topics can be stored directly in the influxDB database.
controllers/#macaddress#/input - line protocol The controller can publish on this topic
Example for a button message
controllers,id=D8F3A5A646FB button_name=1
Example for a diagnostic message
diagnostics,id=D8F3A5A646FB,wifi_bssid=D8F3A5A646FB signal_strength=-50,battery_voltage=2.4,uptime=15530
Example for an im_alive message
im_alive,id=D8F3A5A646FB status=1 #Controller is alive!
im_alive,id=D8F3A5A646FB status=0 #Controller is dead!
controllers/#macaddress#/output - json
This JSON is to be decided by those who want to control the controllers. Good luck!