MQTT Stopwatch / Display

Message Protocol (MQTT Stopwatch / Display)

This device responds to MQTT messages on the following topics. Note that it is a "read-only" device and does not publish (send) any messages at all.

Topics specific to the stopwatch

Note that none of these topics expect any "payload" content. The presence of a message on the specified topic is sufficient (although the presence of a payload will not cause an error).

General Topics

These topics represent info being sent back to the remote controller (operator) by the robot.

Note that the robot name (as represented in red in this table) is optional to help in an environment where multiple robots are playing. The configuration file has a parameter to specify the name to which the unit will respond, and it may be blank. If used, this robot name is actually part of the topic name.

Note that a "warning" message is displayed on the bottom line of the display, in red. On a 2-panel display, 22 up to 22 total characters will be displayed.

Generally, a "status" message is displayed on the bottom line of the display, in blue. If the message has a colon (":") in it, the portion before the colon will be displayed (in orange) to the right of the time display, possibly split into 2 lines favoring the first space as the split point; the portion after the colon will be displayed on the bottom line, in blue.

A "battvolt" message is displayed on the bottom line of the display, in green. Note that the payload should start with the voltage as a number, as shown above. The payload may have additional characters following the number, which are ignored. Note that if additional characters are added, there must be a least one space character terminating the number. Note that the battery voltage is only displayed if the timer is running, and if the configuration parameter (in the config file) "want_battery_message" is set to True.

Specialty Topics

These topics represent commands being sent from the remote controller (operator) to the robot. The display's response to these commands is optional, and is controlled by the "want_specialty_cmds" in the config file. All of the topics generate the same message on the bottom line of the display, in purple. This message is controlled by the "specialty_banner" in the config file

Note that the robot name (as represented in red in this table) is optional to help in an environment where multiple robots are playing. The configuration file has a parameter to specify the name to which the unit will respond, and it may be blank. If used, this robot name is actually part of the topic name.

Additional Background

The following offsite links provide useful backgound info on the general structure of MQTT messages.

• Understanding MQTT Topics
• MQTT Topic and Payload Design Notes
• MQTT Topics, Wildcards, & Best Practices