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Button Control

Important!

The HiveMQ broker has a limit on how often it can be published to. As a result, button publishes can be denied if they are too quick or obstructured by other publishing traffic. The alternative driver for temporary demonstration purposes DEMO_button_control.py is less susceptible to this but it is not a solution.

The button_control driver drives buttons added to the Smartbike and attached to the Raspberry Pi's GPIO pins.

Button class​

The Button class can be used to quickly create new buttons which will read input from a passed pin and publish when the pin is pressed or released. The class functions based on events from the GPIO board.

ParameterTypeDescription
pinintThe GPIO pin the button is connected to
namestrAn identifying name used in logging and to identify in the publishing payload
clientMQTTClientthe standardised MQTT client

MQTT Topics​

The default MQTT topic used in this driver is:

bike/{DEVICE_ID}/button/report

All button presses and releases will be published to this topic.

MQTT Payload​

The published payload on each press and release uses this a JSON structure:

{
    'button' : [button name]
    'state' : [1 for pressed] | [0 for released]
    'timestamp' : [time of publish]
}

Driver Location​

To see the button_control driver code:

Drivers/button_control/button_control.py