So I have a weird issue with ELRS.  No idea what is causing it.  When I power up the quad I get an RXLOSS every other second.  It goes full LQ, so 6:100, then the next second RXLOSS / No LQ, then next second full LQ / 6:100, then RXLOSS, and so forth.

I made a change to Packet Rate, TX power and Dynamic Power (on the Radio), last week.  I reverted those to the prior settings (500hz, 500mW, Dynamic On) and the problem remained.  I then dropped them to 150hz, 100mW, Dynamic On), same problem.  Then 150hz, 100mW, Dynamic Off, same problem.

Tx Side: Jumper T-Pro v1 ELRS, running ELRS 2.5
Rx Side: SPI ELRS on DarwinFPV 15A AIO FC / with BF 4.3.1

This was flying last week without Tx/Rx issues.

Any ideas?

My guess is a problem with the RX. Did you try connecting to another quad, assume no issues for your other quads?
You might want to double-check your CPU load and drop your loop time - I've seen a few rare cases of SPI freezing up, but never seen it repeatedly cut out every second. Maybe also check the board for debris/damage?

(04-Jun-2024, 10:45 PM)Pathfinder075 Wrote: So I have a weird issue with ELRS.  No idea what is causing it.  When I power up the quad I get an RXLOSS every other second.  It goes full LQ, so 6:100, then the next second RXLOSS / No LQ, then next second full LQ / 6:100, then RXLOSS, and so forth.

I made a change to Packet Rate, TX power and Dynamic Power (on the Radio), last week.  I reverted those to the prior settings (500hz, 500mW, Dynamic On) and the problem remained.  I then dropped them to 150hz, 100mW, Dynamic On), same problem.  Then 150hz, 100mW, Dynamic Off, same problem.

Tx Side: Jumper T-Pro v1 ELRS, running ELRS 2.5
Rx Side: SPI ELRS on DarwinFPV 15A AIO FC / with BF 4.3.1

This was flying last week without Tx/Rx issues.

Any ideas?

ExpressLRS V2.5 never worked for me. I have always used V3.X. I don't know if that is the issue with you. Maybe worth a try.

All my drones are on 2.5, there are no issues with 2.5 that I am aware of. 3.x will offer some new features, but 2.5 has been solid for me. I probably have more than a dozen SPI boards, so I am in no rush to update BF on all of them, and then even more serial RXs (my brain hurts to think about it). I got a spare radio and thought I would try 3.x, then thought about it some more and downgraded the radio to 2.5 as well.

(05-Jun-2024, 12:03 AM)mstc Wrote: All my drones are on 2.5, there are no issues with 2.5 that I am aware of. 3.x will offer some new features, but 2.5 has been solid for me. I probably have more than a dozen SPI boards, so I am in no rush to update BF on all of them, and then even more serial RXs (my brain hurts to think about it). I got a spare radio and thought I would try 3.x, then thought about it some more and downgraded the radio to 2.5 as well.

Yes, SPI boards are a pain. I went back to V2.5 because of a SPI board but I couldn't get it working. So I finally updated the firmware to BetaFlight 4.4 and used ExpressLRS 3.X all my quads, fixed wings and transmitters are on V3.X so it is much easier for me.

3.x is a no go, as my T-Pro won't upgrade. I sat on Discord with V-22 and some others one night a couple of months back and it just failed constantly.

I've had no issue with 2.5 in all the two years I've been using it. I'm going to dump to file and reflash BF and see if it still occurs. Worst case I have a few of those horrible ceramic HM Rx sat in a box. But even a working horrible ceramic beats a badly misbehaving built in module. I will try some messing with the quad side tomorrow.

I will be adding a RM Pocket ELRS sometime in the near future, so the 3.x issue will go away, but then I guess I have to upgrade everything to 4.4, I might not, well unless I build something that needs GPS or some other functionality that warrants 4.4 or later.

Hey Path, that sounds like a bad antenna connection.

Not fully clear if the changes you made were proven by OK use after those changes last week, so the fault is later than the changes?




I have a X16S with 3.xx ELRS onboard and that is fitted with a Namimno module on 2.xx.  

I have a recent issue with a no changes quad on 3.xx. Only that one quad, and annoyingly its too intermittant so far to trace, one day good, the next a very few glitches (usually a slow roll right with no throttle). NO warnings, sometimes extremely brief, but rarely all way to ground.  However, the rest are fine on whichever version they are on.

I have seen NO need to update even the Rx's that in theory would be easy. If it ain't broke, etc, etc.

The iffy quad (GEPRC Mk5 5" on 2.xx) has been parked as currently the outer field is long with difficult to get through near waist high tangled trouser snagging mixed grass/tall buttercups/chickory/tall clover/etc I don't fancy having to try to cross to recover anything from!

(05-Jun-2024, 03:49 PM)segler999 Wrote: Hey Path, that sounds like a bad antenna connection.

That is my first thought. Unfortunately i have to take everything apart to confirm the ufl has detached. :/

(05-Jun-2024, 05:24 PM)BadRaven Wrote: Not fully clear if the changes you made were proven by OK use after those changes last week, so the fault is later than the changes?

I have a X16S with 3.xx ELRS onboard and that is fitted with a Namimno module on 2.xx.  

I have a recent issue with a no changes quad on 3.xx. Only that one quad, and annoyingly its too intermittant so far to trace, one day good, the next a very few glitches (usually a slow roll right with no throttle). NO warnings, sometimes extremely brief, but rarely all way to ground.  However, the rest are fine on whichever version they are on.

I have seen NO need to update even the Rx's that in theory would be easy. If it ain't broke, etc, etc.

The iffy quad (GEPRC Mk5 5" on 2.xx) has been parked as currently the outer field is long with difficult to get through near waist high tangled trouser snagging mixed grass/tall buttercups/chickory/tall clover/etc I don't fancy having to try to cross to recover anything from!

Yeah the irksome thing was I wanted to fly it in the Lakes last weekend. It obviously wasn't flight worthy otherwise I would have bagged some canyon surfing action. :/

So I will strip it down probably tomorrow and see what the state of play is. i hope it is the antenna as I have several spares I could swap out with. If not, then I guess it's time for a separate ELRS board.

This quad has been a royal PITA ever since I built it. It flew ok at first and has got worse over time. It could be the Darwin FC is dodgy and slowly dying, but I need to rule everything out before I desolder anything.