PXX protocol

Test build is available (f30eb8c) . No telemetry support in this build.

Mainly motivated by the Frsky R9M which only supports PPM and PXX.

Got my R9 module (30bucks inc Rx), so can help in testing, probably this weekend.
To be sure how to connect it?
Vin & Gnd but then serial PXX, is it via Smart Port or PPM pin ? If smartport, to devo do we need bidirectional invertor? And what about the hartbeat ?

The PXX signal is on the top JR pin for T8SG Plus. On the DSC port tip for other transmitters. The s.port connection is to the bottom JR pin or the DSC ring.

The Jumper and Devo transmitters don't have an input for heartbeat. Deviation will just send unsynchronized with the tx module.

Test build is updated (057b920). This version has at least a 50% chance of working Still no telemetry.

For testing I made a PXX analyzer plugin for Salae Logic.

f30eb8c on T8SG V2 Plus dont start

Just tested both f30eb8c and 057b920 on a T8SG V2 Plus and everything worked fine. The PXX protocol output is only correct with 057b920 though.

If you were running a 5.0 build the filesystem also needs to be copied when moving to a test build which is based on the nightly builds. Backup/restore models, and tx.ini and hardware.ini if you've changed them.

The transmitter turned on. But the protocol does not work. All channels in inav are = 880. If you move the sticks, the RX loses.

Is that behavior with build 057b920 ? The PXX data was not correct in f30eb8c.

What radio module and receiver are you using? Do they have any status lights that might indicate what is happening? Sometimes a video of the behavior while turning the tx on and off is an easy way to communicate what's happening.

R9M + R9MM
After switching on, the first channel = 1500. The remaining channels (2-14) accept the values 880.

Thanks for testing. Please include the build number when reporting the results.

Test build is updated (66fc9c6). Added a protocol option to set country code and added support for binding.

Please test this build, first setting the country code then going through the bind procedure. The country code must match the firmware on the R9MM. Click on the protocol name to access the protocol options. Also set the Fail-Safe protocol option to RX for testing.

For binding, after pressing Bind on the t8sg you have 5 seconds to power up the receiver in bind mode. No need to press bind button on the R9M. The LEDs should indicate a successful bind. Please record what the LEDs do during this procedure.

Previously I thought the bind wasn't critical because the tx and rx could be bound as with PPM. But with PXX one of the PXX data bytes is used as a tx id for model match. So when using PXX the bind must be done through through the Deviation bind option.

Test build is updated (187edbc). Added support for range test and power level setting. Highest four deviation power levels correspond to the four power settings available on the R9M. All failsafe modes should work now, but please test first with Failsafe protocol option set to RX. PPM output protocol implementation is changed to DMA.

The PXX rx number is now taken directly from the model fixed id. This makes moving an R9M module from other transmitters easier. Set the fixed id the same as the receiver number in the other transmitter and then it will not be necessary to re-bind when moving the R9M between transmitters.

Test build is updated (fcf47e3). Added support for s.port telemetry. Frsky said the s.port output on the R9M is normal polarity so it should work without hardware modification. (Though they wouldn't share the latest PXX spec.)

Hi Hexfet, Iam trying your buildbut have some questions.

U7E(256), flashed with pxxtestbuild, connected R9M module, R9 gnd to the 3.5mm connector plug gnd , ppm pin to the 3.5mm plug top of the pin.

The R9M I power from a 2s battery, the firmware is the so called "Flex firmware", FW-Ranger9-FCCBeta-181116

Ok when in Deviation, I go to PXX press bind, nothing happens to the LED at R9M it stays red.

any advise?

The R9M manual talks about both red and green LEDs. Is that correct? What do they both show when you power on the module? Does it change when you press bind in deviation?

Does everything work correctly when you use PPM instead of PXX?

Ok I did quite some more digging around:

yes R9M using CPPM works fine.
Channels 8
CPPM settings: center1100,deltapw 500, notch 400, framesize22500
To bind: push rx button power on, then push r9m button and poweron.
R9M dip switches I have them both on /up, according manual no telemetry 200mw.


Now when R9M / R9 binded it keeps bind even when devos switched off and ppm stream stops.
So now tried a PXX stream 8 channel and also 16 channel it should auto detect, R9m still bind but no movements of channels , tried restart etc no luck,
no movements.

Then tried bind R9M via deviation and in FCC mode and once out of 15 times or so the leds R9M start to flash/alternate and I loose the bind with the Rx, but no controls.

Thanks for the testing. More is coming

The hardware connection is good since PPM works.

The R9M manual says during bind the LEDs should be green on and red flashing. Is that what you see only sometimes when trying to bind PXX? What do the LEDs (both green and red) on the receiver look like when that happens?

The manual says the normal state is green flashing and red on. Do you ever see that state on the module?

Please set Fixed ID to 0 in PXX model and try binding again. What happens with LEDs on both R9M and receiver?

Also try the range check on the transmitter menu. According to the manual with range check activated the R9M LEDs should display green flashing and red off. Please check what the LEDs display.

Hi some more testing:

When bind in ppm mode I see channels move, led rx green flickering.
Led R9M solid red led on and green led flickering.

When switch to PXX and repower (8 and tested 16ch) the leds stay same, however no channels data received. (so all is still bind and connected,but nostreamchannels from pxx read.)
But something strange when not touching sticks allstay bind, but when moving stick to full deflection randomly, the R9M led go to red and all unbind. I can't saywhat is causing sometimes it happen fullroll ,but then next time happen fullrudder.
I need repower R9M txmodule to get link back inlock.

Binding I tried 000000 or 222222, both case it does not work not in FCC or EU also the led stay redon R9M, no change.

hope it helps let me know if more tests ideas.

Thanks for the report! Probably when the sticks are moved the PXX signal changes and the module gets confused, maybe trying to sync with PXX.

Test build is updated (c02d22a). I found some indications that the order of the CRC bytes was backwards. This version swaps them to the order in the more recent docs.

No need to test with PPM anymore. Check if PXX bind works with this version. Also please try the range check just to see if the R9M LEDs change.

The testbuild I find and loaded is different, fcf47e3

And still no pxx channels encoded, no reaction to bind command,selecting range check in transmitter menu no difference in R9M led

Sorry, I missed a step somewhere. The fcf4 version does not have the latest changes. I've uploaded the c02d version. Please test binding with c02d. Use fixed id 0 - not sure what range is allowed.

Thanks!

Let me know if more tests to be done.

BTW I am on test builds anyway, could you merge at some point the other test builds, PXX- latency - timing all into one big test build?
So can fly test that all at once?



Aaaghhh I accidentally deleted my long test results post.…...