PXX protocol I'm confused

[tilmanb]

Will FrSky modules some day support PXX out of the box?
And is https://code.google.com/p/er9x/download ... p&can=2&q= still the place to go to get the PXX firmware?
I always thought this was a more or less official FrSky thing (though preview), but this does not look very official to me.

Also does PXX have similar features like model match? Will I have to re-bind every time I switch model or is the model id/key somehow part of that protocol like with DSM?

Thanks

[Kilrah]

The new XJT module that will come out soon will have official PXX support. As far as we know the older ones would get a firmware update as well.
Yes there is a model match function. You obviously don't need to rebind when you change model... Or if you do it's because you selected the wrong model

You can get the current beta PXX firmware, but it doesn't have any advantage at this point as there is no receiver support. It was only meant to test the communication between radio and module.

Sent via mobile

[kaos]

what exactly is the advantage of PXX compare to PPM16 besides the model matching?
sky9x board now the 2nd ppm is activated in ERSKY9x. I just wonder what PXX would do that PPM16 won't?

[Rob Thomson]

The most important thing... Latency.

You remove the ppm conversion, making everything more locked in (to use spectrum marketing talk)

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[tilmanb]

You can get the current beta PXX firmware, but it doesn't have any advantage at this point as there is no receiver support. It was only meant to test the communication between radio and module.

Ah. That is some good advice.
I just assumed that the over the air protocol was unchanged. I mean surely they don't currently modulate PPM directly on 2.4Ghz, or do they?

Spinning this thought to the end would mean that new PXX receivers will become available (perhaps via firmware upgrade)?

[tilmanb]

You remove the ppm conversion, making everything more locked in (to use spectrum marketing talk)

That is certainly the case with Spektrum. But FrSky seems quite open with their specs. (No surprise since they don't have the whole stack under their control)
I'm all for retiring PPM, it's a stupid protocol in a digital world.

PS: I fly Sketrum mainly because I can read that DSM data stream serially from the Satellite receiver boards. Though still with some effort, the timing and framing is bizarre.
In so far, I have to say I embrace that whole PXX idea. As long as I can get that datastream out of the receivers. We'll see.

PPS: While I'm trashing PPM. Wouldn't it be cool if we could hook up our RC flight gear on a open standard digital bus (like CAN perhaps) with high voltage support and bi-directional communication? Don't say S-Bus, they had their chance and did it wrong (Hubs, small address space, closed specs - WTF?). Anyway, enough rant.

[Kilrah]

The over the air protocol was unchanged in the beta firmware, hence no new features - but the new modules/receivers/firmwares will add a new RF protocol referred to as D16, with support for 16 channels and the new gimmicks.

See the announcement: viewtopic.php?f=5&t=72&p=38664#p38664

As long as I can get that datastream out of the receivers. We'll see.

As you can see the receivers will have SBUS out. Less twisted than DSM already.
Telemetry goes on a separate bidirectional port.

[tilmanb]

Got it. Thanks.

[kaos]

The most important thing... Latency.
You remove the ppm conversion, making everything more locked in (to use spectrum marketing talk)

ha ha, that goes back to the discussion whether in the real world 1/10 of a ms does anything "in reality". with servo response is still in the ms range. If we have a Tx with same gimbal just a different board and a really good pilot , probably that can tell the 'truth'.

[Rob Thomson]

Exactly!

But if we can improve it... Why not

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[Kilrah]

It will at least be better for wireless trainer scenarios. Currently 9x->frsky tx->frsky rx->9x->frsky tx->model is VERY slow.