RSSI either 0 or 100% (kind of)

[Andy7]

Being somewhat curious to know whether I'm about to failsafe behind a damp bush in this weather I've gone back to trying to get my RSSI working properly again.

Using an XM+ RX with the little RSSI pad connected to the RSSI pad on my Matek 722 STD.
Throwing the RSSI up to my OSD while flying rather than all that back and forward malarky.

I Connect to betaflight, power up, switch on radio, I see 100% in the RSSI value in the configurator. Turn off the radio, it quickly drops to 0% So, that kind of shows that it's working after all... nice.

I then did a test where one of the boys took the radio out of the ofice (foil-backed insulation will block a LOT of signal so they don't need to walk miles) and walk away up the street until the signal gives up.

I see 100% for ages, which makes me feel great, then a SUDDEN drop off in signal and HUGE fluctuatons between 0 and 100 for no aparant reason with very little movement.

Any clues as to why I'm not getting a more gentle drop-off? Something's saying scaling to me here but I don't see any calibration parameters in BF.

  

[ched]

Silly question but I thought XM+ does rssi on ch16 by default? So just set BF to have rssi on aux12 should work shouldn't it?

Using the rssi pad on rx needs to go to fc rssi pad which appears to be marked on your FC but Matek don't seem to mention it at all????
If I remember correctly the rssi pad out on xm+ should give out 0v to 3.3v. So you can measure it with a multimeter if you want. Also can't you put your tx in range check mode and then no one has to walk far to see rssi change

Just remembered that there are multiple versions of the xm+ fw  with rssi on 16, on 8 or not on any channel!!!
DONT accidentally flash ACCST 2.0 !!!!!!!!!!!!!!!!!!!!!!!!!!

[Bad Raven]

There are various YT Vids on doing this, also some of the comments are useful  (Amongst the dross!!), have you looked at these??

[ched]

Looking at fc in more details the rssi pad appears to be pwn not 0 to 3v! Does the xm+ rssi pad give pwm out for rssi?

[Andy7]

Looking at fc in more details the rssi pad appears to be pwn not 0 to 3v! Does the xm+ rssi pad give pwm out for rssi?

i'll stick it on the scope and see what its putting out.

[Andy7]

Aha... good discussion on exactly this here:
https://www.multi-rotor.co.uk/index.php?topic=21025.0

Think I'll have another go at looking at the signal on a channel. Didn't seem to work las time. But got some time with all this wind!

[ched]

Aha... good discussion on exactly this here:
https://www.multi-rotor.co.uk/index.php?topic=21025.0

Think I'll have another go at looking at the signal on a channel. Didn't seem to work las time. But got some time with all this wind!

If you flash the xm+ with an appropriate fw it will output rssi on aux channel. There is then no need to use tx to retransmit the rssi back to rx. Just select the aux channel in BF as rssi and it should work fine.

The thread you linked to brought back memories of messing about with add on osd boards and how tricket they were to setup... So much easier now it's all in BF osd.

Good luck.

[Andy7]

Yup, I need to reflash my firmware anyhow as I had the wrong flavour on there a little while ago and just don't get ANY time to mess about with this. So.. good old spring-clean today.

[murpia]

To get XM+ RSSI working off Aux16, make sure you turn OFF analog RSSI. It's not on the same configurator tab where you turn ON aux channel RSSI, so is easily missed...

[Andy7]

Yup did that. RX decided that it would rather die than be flashed with the proper firmware.