Lost messages

[d-ferenczi]

Hello Everyone,
I have noticed that if I send (e.g. lora_node:cast/3) messages too frequently, messages might get lost.
Communication works well however, if I wait for a time aligned to the airtime of my message before I send the next one.

As I'm new to using low-level communication techniques, first of all, I wanted to ask if this behaviour is intended and if there are other strategies (e.g. blocking until cast finishes) that make sense in practice.

[UncleGrumpy]

This is to be expected. If you are concerned about the delivery of a message you should use lora_node:call, you will receive an acknowledgement, which you should wait for before sending the next message. The lora_node:cast is more akin to UDP - where occasional packet loss is acceptable.

Also note, the airtime (% of time broadcasting) and dwell time (how long you stay on a particular frequency) that you can transmit is restricted by regulations. This varies by global region; but if you are sending a constant stream of data you may get a visit from men in suits. You may find this helpful for finding the regulations for your region (this applies to plain LoRa as well as LoRaWAN):

https://www.thethingsnetwork.org/docs/lorawan/regional-limitations-of-rf-use/

This repo is also mainly a low-level driver for LoRa modems, not necessarily a robust and ready to use implementation of any particular protocol or networking solution. The “node” application is better thought of as a starting point for creating a custom mesh network.

I am in the middle of a couple different projects, but I do plan on giving this repo some more attention in the near future, and PRs are welcome. Before submitting changes I would recommend opening an issue that explains what features or changes you would like to see, and where we can discuss implementation before you spend too much time on the code.

My plans are to add region/channel support, so users have the option of using a “channel” to set the frequency. For the lora_node, I would like to finish multicast support, and add channel hopping for larger messages. I also want to add basic Meshtatic support, Davide (AtomVM’s creator) has an implementation for this in his PocketOS repo.