LoRaWAN - manually set TX Power level?

[K4KDR]

Greetings! Using an example sketch such as LoRaWAN_ABP, I am in search of the 'correct' way to lock in the TX Power level.

In src/protocols/LoRaWAN/LoRaWANBands.cpp, I see that for each bandplan there is a parameter called .powerMax.

There is also a specific command parameter (sorry if not the correct term) in
/src/protocols/LoRaWAN/LoRaWAN.h called setTxPower

Lastly, associated with each module (sx1276, in my case) there the standard directive radio.setOutputPower

What I do NOT know is, which setting gets the "last word" - i.e., has the highest priority.

The context here is 2-fold... for experimentation purposes I would like to be able to guarantee that my device is transmitting at its maximum RF power level (without regard to any setting established by the LoRaWAN bandplan selected)

-and-

I need to be able to impose a much LOWER TX power level to safely use an external RF amp.

Many thanks for any guidance on how to lock in a single, specific RF TX power level using RadioLib's LoRaWAN capabilities.

-Scott, K4KDR

[StevenCellist]

node.setTxPower() overrules radio.setOutputPower(), but is limited by band.powerMax. Make sure that you comply with local regulations & laws (the actual, real laws that may earn you a visit from police) before increasing the powerMax value. Otherwise just use setTxPower().

[K4KDR]

Thanks a million for the reply - that is very helpful!

And thanks also for the cautionary and very important note about staying within legal power limits.

I'll continue testing now without having to wonder if I am adjusting TX Power in the proper way!

[StevenCellist]

If you can #define RADIOLIB_DEBUG_PROTOCOL 1 in the BuildOptUser.h file, you will get a lot of output from what happens under the hood - you should also be able to see some TX configuration happening when you call setTxPower(). But it may be too overwhelming, as it also spits out lotssss of other details.

[HeadBoffin]

But that's because @StevenCellist likes Big Logs, he can not lie.