Hello.  First time poster (had to say that).

So I have 14 quads that all use ELRS so I'm vaguley familiar with how it all works. But, last night I was troubleshooting a new build in Betaflight and could not get the transmitter to work (moving sticks and seeing the bars move in BF).  Everything was set correctly from Ports to CRSF etc.  So I decided that after hours of pulling my hair out trying different things and soldering the RX to various UARTs, that I would remove it and plug in a BetaFPV Flat ELRS I had laying around.  It instantly worked first time.

Great, but here's the question.  My BetaFPV RX has DIY 3.0.1 FW on it from factory, and my transmitter is a Radiomaster TX16S running 3.2.0 ELRS.  HOW IS IT THAT THE  3.2.0 TRANSMITTER IS ABLE TO TALK TO THE 3.0.1 RX?  I thought this wasn't possible.

All major firmware versions of ExpressLRS are compatible with each other. So any 3.x.x version is compatible with any other 3.x.x version, and any 2.x.x version is compatible with any other 2.x.x version. However, a 3.x.x version is NOT compatible with a 2.x.x or 1.x.x version.

OK yes, I remember now.  Thanks for reminding me.  Knew there had to be a reason.