Creating a channel

Support
1

Hello,

I’m new to the community and I’ve been trying to find out how to set up a channel for MQTT.

Unfortunately, there doesn’t seem to be anyone around me.

I am not sure if I missed something, but it seems really complex.

Can anyone point me in the direction of some guides?

Thanks.

2

Can be a bit complex as there are lot of options.

For the most part channels are only really relevant over Lora. Ie users need a ‘common’ channel to be able to communicate. The channel defines encyption settings, so that can have ‘private’ channel(s) and/or public channels (with a known key)

With MQTT, you can configure which channel(s) your device will upload mesages from - ie uplink, is copying a message from the lora/meshtastic mesh to the MQTT Broker.

and/or downlink - where download messages submitted to Broker (by others), and transmit over Lora (and are visible on your own node!)

You dont need specific channels as such, you just choose which channels are up/downlinked. You do need to be careful with downlinking, in case you download lots of messages from MQTT and transmit them over your local mesh.

… if want to communicate with people over MQTT (rather than Lora) technically the channels dont really matter, the MQTT ‘Root Topic’ will be more important, as some topics might be very busy potentially with messages ‘uplinked’ from many disparate meshes.

3

Thanks, that’s exactly what I wanted to avoid - downloading lots of messages.

So changing the root topic and not the channel should avoid that?

4

To be honest I dont have much experience with downlinking (ie downloading from MQTT) - so might be missing something.

But as I understand it your device will download any message published on the MQTT server, and if its able to decode it (because has the same channel key etc), then it will be ‘transmitted’ on the local mesh (provided downlink is enabled)

So if you setup the default public channel (like LongFast), with the default key, then anyone (from anywhere) that uploads messages to the same root topic, will appar on your local mesh.

In general will get a lot of traffic, if downlink a common channel like LongFast - unless using a obscure Root Topic! But less traffic if use a less common channel+topic