Tasmota: MQTT Topic Case Sensitivity

[thehookup]

Since my Tasmota retain video I've been helping a bunch of people troubleshoot their command topic issues. A theme that I am seeing is that tasmota is really forgiving about errors in command topic and still processing commands. For instance:

Tasmota has the command topic "cmnd/sonoff/POWER", but because it is subscribed to "cmnd/sonoff/#" it will also respond to commands send on "cmnd/sonoff/power" (lowercase) and "cmnd/sonoff/POWER " (extra space at the end). On the broker these are different topics and can therefore retain different messages.

I'm not sure if this is by design, or just a quirk of the way that command topic is processed, but I think some mystery switching issues (that are ultimately caused by errors in user configuration) could be avoided if tasmota only responded to the case sensitive correct topic.

Thanks for all your hard work!

[ascillato]

Hi,

Thanks for helping on solving users issues.

Tasmota uses trim to eliminate spaces and uppercase to process all parameters, so that behaviour is by design.

If we make Tasmota to accept only topics with uppercase and without trailing spaces, we would be braking backward compatibility resulting in a bunch of new issues.

I think that should be better to document in the wiki and in your videos this configuration issue that a MQTT broker can have (power and POWER are different topics from the Broker side).

Thanks you very much on pointing this.

[ascillato2]

I will add this to the wiki.