I understand your point and it is a valid concern meaning that I can see why it might be nice to be able to configure different ports as you suggest. However, given the current underlying lora stack, the data rate would not remain constant and the application developer would still have to handle a message being sent back if it was too big once the data rate was lowered out from under them.
Note that adding setting the data rate on a port basis is really an implementation detail of our lora stack. The reference design allows the application developer to set the port and data rate in the McpsRequest, meaning on a per message basis. This got morphed into doing this on a per port basis as access to the reference design's McpsRequest is “hidden” by the current lora api. However, even in the reference design case, the data rate used for that McpsRequest could change. I was considering modifying the api such that the data rate was specified in lora_app_port_send() when the application wants to send a frame. However, the data rate could still get changed and to me this makes it not as useful. Furthermore, I still think it will be rare for the application developer to dictate the data rate (but I could be wrong here). Honestly, in most cases I think this adds some extra burden on the app developer to specify a data rate. A possible consideration would be to modify the code so that the application developer can specify the data rate on either a per port or per message basis if they desire, and that the message would always be sent at that data rate. > On Oct 24, 2017, at 3:56 PM, Christopher Collins <[email protected]> wrote: > > On Tue, Oct 24, 2017 at 01:56:22PM -0700, will sanfilippo wrote: >> Hello: >> >> I would like to propose some changes to the lora api and I want to see if >> folks had any comments or issues with the following proposal. > > [...] > > It sounds reasonable to me. There is just one thing that stuck out for > me: > >> 4) Setting the data rate on a per-port basis is just overkill. I cannot >> imagine the application wanting to change the data rate on a per port basis. > > The application likely contains several packages not written by the > application developer. If any of those packages use LoRa, and they have > specific data rate requirements, per-port configuration might actually > make sense. If a package needs to send packets of a particular size, > for example, then it might have minimum data rate restrictions. I'm not > very familiar with LoRa, so I don't know if this is a valid concern or > not. > > Chris
