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Permalink Reply by Vernon Barry on May 2, 2012 at 7:29pm

Anyone used the Spektrum adapter on the APM2?

It's known that the spectrum adapter does not work with APM2. This is because the entire FTDI and PPM encoder are now done on a single chip and thus the code is entirely different.

Info on APM2.0 PPM http://code.google.com/p/ardupilot-mega/wiki/APM2Encoder 

This is why it won't work.

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Permalink Reply by Crispin on May 2, 2012 at 11:12pm

Thanks Vernon. Not the reply I was hoping for :(

Is this specific to the Spektrum adapter or are other affected as well. Bit confused by the fact that others have it working.

Is the APM2 encoder likely (possible) to get a firmware which will allow it?

Cheers,

Crispin

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Permalink Reply by Vernon Barry on May 3, 2012 at 3:51am

Sure, it's all open source. The issue here is proven working code vs the hack that you could attempt yourself. When you jack up the code in the PPM encoder on APM2.0, that's also the same chip that gives you the USB connection, so then you also cannot program the APM mega 2560.

Let's be hoenst about this, the whole point of the spektrum adapter was using the super light weight tiny reciever, mainly aimed at indoor super small quads. Because the new APM2.0 is smaller, lighter, and just generally better, that "feature" to use the small reciever wasn't a priority.

 

Further, let's get into just using a satellite receiver. I could be wrong but is has way less features right? I mean I don't think you can set up failsafes in the satellite and we had a huge discussion in another thread were a new guy with a 4 day old quad had it fly off to never never land because he lost radio range and didn't have failsafes. Being the satellite in theory has less range, less interference rejection and likely no failsafes, not exactly the thing you should be using outdoors on a quad you might want to get some radio range on. Face it, the satellite receivers are really just there for diversity and not intended to be used standalone so just because somebody came up with a hack to use one, it may not be the best way to go.

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Permalink Reply by Crispin on May 3, 2012 at 1:35pm

I would rather the code be done properly instead of a hack (me: hack - clever folk: Do code properly :) 

My main reason for wanting this to work was so I can lose the bulky box and more importantly, the added nest of cables (even with the flat ribbon cable) between it and the APM. It'll fit into my custom shell much better.

Not tried (and don't have the means to) but I suspect all the brains are in the satellite and the receiver is just a PPM -> PWM. At worst, the "main" receiver is the same as the satellite and, as you say, just forms the other half of the diversity setup. My thinking is that if you bind to the satellite and not the other box, it is in fact the good stuff. Maybe it will manage the fail safe.

I take your comment about reduced range, for me, without FPV, more than 100-200m is to far on a quad. I've lost orientation and crashed anyway :(

Why would the APM2 have the wiki and the solder pads to allow for this to be setup? If it does not / will not / should not be used then this seems a bit odd. Maybe someone can comment from a hardware perspective.

Just guessing on all the above and don't have any means to really test it.

Will try find my APM1 and see if I can get it working on that.

Any thoughts though on how the posts on the blog apparently got theirs working? As I've said, the comments seem rather disjointed.

I've been following the "4 day" quad thread. I agree that if by removing the main box I lose fail safe then it's a non-starter.

Cheers,

Crispin

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DeveloperPermalink Reply by John Arne Birkeland on May 4, 2012 at 12:52am

Ok, here is the deal.

- Spektrum satellites output servo channel data as a slightly non standard serial data stream.

- Spektrum adapter, is not a Spektrum to PPM converter. It is just a 5V <-> 3.3V converter for the Spektrum satellite.

On APM1 there is a custom firmware for the 328p chip so that it can understand the Spektrum serial data.

At the moment, there is no custom Spektrum firmware for the APM2. The old APM1 custom firmware would have to be completely rewritten, since the new 32U2 chip also has to support the Arduino USB bootloader at the same time.

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