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Permalink Reply by Doug Weibel on March 5, 2010 at 8:54am

I have looked at this before and it is a nice project.

I have on my "To Do" list working out use of Spektrum/JR satellite receivers with ArduPilot Mega. We should be able to reprogram the PPM processor to interface with one or more satellite receivers and do away with the receiver in our system. That will be a nice space and cost savings.

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Permalink Reply by Natalius Kiedro on March 5, 2010 at 9:29am

Binding (in the absence of a main receiver) is in the AR7212 code published today. The AR7212X has a pause and a bit pattern recognition algo for frame analysis you may port to Arduino. Support for Unilog (SM Modellbau, Germany), a small formfactor sensor for altitude, temp., airspeed, voltage, current, temperarure is build in. Support for CHRobotics AHRS will come next. Support for Xmega has been implemented at the level of servo-PWM - as soon as Mark Alberts has finalized ring buffers for the Xmega, 5 UARTs are sufficient to read 2 satellites, Unilog, CHR6d/m, GPS and downlink telemetry, as the latter two can use one port together. As the AR7212 primarily addresses the "normal" RC-pilots with larger vehicles, the 6 autonomous modes are reserved for panic, convenience & pilot training options.

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Permalink Reply by Natalius Kiedro on March 19, 2010 at 10:13am

Hi Doug,
I forgot to mention that the Razor will be also supported. Since a week I have one from a German distributor - do you know why Nathan Seidle finally decided to bring out the 168 instead of the 328-based Razor, whose SW development you were involved in? I mean the price difference is in the order of a percent - was the price calculation sooh demanding?
Best
Natalius

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Permalink Reply by Chris Anderson on March 5, 2010 at 10:49am

I'm really interested in this project. I thought the Spektrum signal was proprietary...how did they get around that?

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Permalink Reply by Pbreed on March 5, 2010 at 11:23am

RCgroups has some discussion on this, it basically looks like 115200 8,n,1 serial at 3V levels.
It sends frames and the format can be found by searching rcgroups.
The format look really simple 16 bit signed ints for each channel.

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Permalink Reply by Natalius Kiedro on March 5, 2010 at 11:35am

I am not aware that the discrete serial frame format of Spektrum has been published as an IP issue. Please find the patents by Paul Beard - I scanned them half a year ago - please let us know if you find something relevant. Even if there is protection by now, a company which has a 2nd hobbyist market is in a better position than its competitors, because on the long run it will stabilize the company. And if Spektrum doesn't like such support - well - the AR7212_C is already prepared to move to a another platform...

Also: Any company (and the major ones like IBM have seen this long time ago) will sooner or later recognize that there is no protection against the rip-off by patent lawyers on one side and people's creativity on the other...

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Permalink Reply by Morli on March 5, 2010 at 11:38am

This might help , the document is very interesting read if not a good summer project too
http://www.rcgroups.com/forums/showatt.php?attachmentid=2686737&...

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Permalink Reply by wurpfel on March 5, 2010 at 1:59pm

hi folkz

the com with the sats arn`t very special. look here
http://www.rcgroups.com/forums/showpost.php?p=10571741&postcoun...

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Permalink Reply by Natalius Kiedro on March 5, 2010 at 3:58pm

Hi CJ (Wurpfel),

unfortunately the link you gave does not lead to anything. Please find the relevant name either in the source or in the acknowledgement part of the word doc downloadable.

To all: There is a continuation of this thread at http://www.mcselec.com/index2.php?option=com_forum&Itemid=59&am...

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Permalink Reply by wurpfel on March 6, 2010 at 12:35pm

Hi folkz


ok, lesson learned!



the link was the start of the protocoll-decoding, and it`s polite to point out here in english ;-)
the know-how is fixed in the german-RCline-thread about a micro--6dof-system.
the main thing is to bind the satelite on the DSM2-TX..SOLVED!

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Permalink Reply by Natalius Kiedro on March 6, 2010 at 5:38pm

Sorry,

RW is German but he posted his analysis in English before it moved to Microcopters..

Binding: Holger Graf who integrated RW's code into the latest Flight Control explicitly stated a month or so ago that binding needs a main RX but that this does not to be connected to the satellite during the process. Interesting, right? If you have newer information from another thread please let us know - at least I'm not aware that it is in the 6DOF thread.

Anyhow, binding with or without main RX connected or non-connected to the latter is primarily a question of convenience. What was (perhaps) missing for UAV applications was an interpretation of the unknown first two bytes. I posted an interpretation some time ago in a German forum and today at RCgroups: http://www.rcgroups.com/forums/showthread.php?p=14521566

I've to correct myself at the point that the bit pattern recognition algo based on this interpretation is already in the published code. It is timer-saving, works nicely on ground, but so far not tested at extreme conditions.

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Permalink Reply by Natalius Kiedro on June 13, 2010 at 3:11pm

Let me invite myself to celebrate the 50th successful flight of an Alpina 4001 CME with the AR7212 today (about 25h air time). I think it is fair to claim that the concept behind the AR7212 is not a "proof of concept" but an "air proven concept". N.

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