Traxxas ALIAS

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21 Mar 2014 00:26 - 21 Mar 2014 00:27 #21700 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
When I bought mine, I also bought two sets of (4) stock motors. Then I went and bought a set of (4) motors from Benedikt. Haven't had to replace the stock motors yet.

I found out a long time ago that things don't fail as often when I have a lot of spares. :P :P :P
Last edit: 21 Mar 2014 00:27 by Ssayer.

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24 Mar 2014 03:14 #21779 by victzh
Replied by victzh on topic Traxxas ALIAS
OK, I've got it a bit ahead of schedule and managed to mount on my V929 frame. They have different props orientation, so I now fly my motors is most unnatural configuration CW motors do CCW, and CCW do CW. TX is not so easy to solder to, but RX is a bit easier.

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24 Mar 2014 13:51 #21791 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
I see a Deviation in the force in the not-too-distant future! :P

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04 Apr 2014 15:04 #22123 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
@victzh: Probably not high on your list, but have you had a chance to look into it yet?

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04 Apr 2014 15:10 #22124 by victzh
Replied by victzh on topic Traxxas ALIAS
I soldered to SPI bus and successfully took several traces from it, I wrote a (crude) decoding script and verified it's really CYRF6936 commands and not some garbage. I did not analyzed it in a thorough manner - weekend is ahead of us ;-) But you're right, I have some other projects so I did not pay this one too much attention. I will though.

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21 Apr 2014 18:52 #22635 by victzh
Replied by victzh on topic Traxxas ALIAS
OK, some progress on the weekend. I got clean SPI trace, my previous one seemed to be noisy. I polished the decoding script so that I can see real packets transferred.

The system has telemetry/presence, so TX knows that it transmits not into thin air, but to someone. At least battery level of RX is reported, may be some other info is sent back as well.

The packets are pretty simple - 16 byte packet, 2 bytes per channel, MSB first. Values are in the range 0x000-0xfff (0-4095), middle value is 0x07ff (2047). Zero corner for both sticks is left bottom.

No CRC, no frequency hopping.

The only unclear thing is how TX id is passed and how all the negotiation goes. It begins on one channel and RX seems to be transmitting some identifying sequence constantly, then transmission goes to another channel.

Still working on it, just wanted to report progress.

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21 Apr 2014 19:25 #22636 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
Really appreciate the update (heck, I really appreciate the fact that you're working on it!!). :)

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21 Apr 2014 20:21 #22637 by SeByDocKy
Replied by SeByDocKy on topic Traxxas ALIAS
Victzh is just amazing ..... :)

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08 May 2014 04:37 #22988 by Machy2k
Replied by Machy2k on topic Traxxas ALIAS
If you figure out the protocol and get it to work, will it have or be able to have Exponential??

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08 May 2014 07:58 #22991 by victzh
Replied by victzh on topic Traxxas ALIAS
A bit busy with V977, and waiting for some parts for Alias, so there is a delay.

I think, yes, it will. Why not?

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08 May 2014 21:29 #23037 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
(just quietly lurking and waiting) :silly:

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08 May 2014 21:38 #23038 by victzh
Replied by victzh on topic Traxxas ALIAS
I always keep it in mind, but the more popular thing - V977 - got my attention. And it will be my first CYRF6936, while nRF24L01 I can read hex files not looking into datasheet ;-)

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06 Jun 2014 19:10 #23941 by Ssayer
Replied by Ssayer on topic Traxxas ALIAS
(just quietly lurking and waiting) :silly: :P

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06 Jun 2014 19:46 #23942 by PhracturedBlue
Replied by PhracturedBlue on topic Traxxas ALIAS
victzh. Can you post spi traces? Working with the CYRF is pretty easy. Throwing something together shouldn't be too hard. I can take a crack at it if you don't have time.

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06 Jun 2014 21:32 #23943 by victzh
Replied by victzh on topic Traxxas ALIAS
Later today, OK? I figured the packet structure, and there is definitely telemetry - RX presence and RX battery which I did not touch yet.

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06 Jun 2014 21:59 #23945 by PhracturedBlue
Replied by PhracturedBlue on topic Traxxas ALIAS
I couldn't work on it this weekend anyway, so no real rush. But it sounds pretty straight forward to implement from what you've said so far.

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09 Jun 2014 06:03 - 09 Jun 2014 06:07 #23982 by victzh
Replied by victzh on topic Traxxas ALIAS
I was a bit wrong about CRC - they use CRC seed of CYRF chip which varies with each packet along with SOP. They use two sets and I don't know connection between TX id (I don't even know the location of this id) to CRC seed/SOP.

Attached are several SPI traces - one is just RX without TX being turned on, second is L and F switches, last is both sticks in several positions.

I figured from my own decoding that the packet structure is following:

16 bytes, 8 channels each 2 bytes MSB, last 4 bytes are always 7F007F7F. Values are between 0 and FFF, middle 7FF

Order:
1 ch - always 01FF or 07FF
2 ch - Elevator, 0 - bottom
3 ch - Aileron, 0 - left
4 ch - Rudder, 0 - left
5 ch - Throttle
6 ch - flags, default 010A, light 014A, flip 410A
7 ch - 7F00
8 ch - 7F7F
Attachments:
Last edit: 09 Jun 2014 06:07 by victzh. Reason: Attachment failed

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09 Jun 2014 06:08 #23984 by victzh
Replied by victzh on topic Traxxas ALIAS
Another one.
Attachments:

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09 Jun 2014 06:09 #23985 by victzh
Replied by victzh on topic Traxxas ALIAS
Third one.
Attachments:

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09 Jun 2014 16:34 - 09 Jun 2014 16:34 #23992 by PhracturedBlue
Replied by PhracturedBlue on topic Traxxas ALIAS
Yeah, the CYRF is different than any of the other modules in how encryption is typically done.
The SOP code and CRC seed are typically used (in conjunction with the channel). In the Devo protocol the data itself is also encrypted, but that really doesn't help much.

How does binding work with the TRAXXAS? Do you need to bind every time, or do you bind once and have it remember? Does the Tx wait for the Rx to become available before starting transmission?

Looking at the data you sent There are 2 channel configurations:

Channel 0x15 is used for Rx, 0x1a is used for Tx

CHANNEL 0x15: CRC=0x616a, SOP=dd 26 7c 50 66 cd 7c 50
CHANNEL 0x1a: CRC=0x2828, SPO=e2 f8 cc 91 3c 37 cc 91

The Rx reads the MFGID before doing anything, so it is likely that it is used for generation of at least some of the above parameters. In your case the MFGID is: e8 35 8f ae 67 fe

Before binding, we see that the Receiver sends:
03 e8 35 8f ae 67 fe 0e 00 01 02 00 01 0b 00 00 (which includes the MFGID)
Once it receives a packet back:
0b ff 07 ff 07 ff 07 ff 00 00 01 0a 7f 00 7f 7f
0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b 0b
It transmits this:
04 02 00 01 0b 00 0a 07 10 00 00 00 01 0b 00 00

I believe that probably completes the handshake. Once that is finished, all communication happens entirely on channel 0x15
It then receives:
07 ff 07 ff 07 ff 07 ff 00 00 13 14 7f 00 7f 7f
07 07 07 07 07 07 07 07 07 07 07 07 07 07 07 07
And responds with the following which is likely temlemetry:
07 00 0a 06 10 01 00 00 00 00 00 00 00 00 00 00

CRC and SOP don't change for a given channel.

While we don't have a lot of information here, this protocol does not seem to use a key-hopping scheme (like DSM*). But we'll need a lot more info to be able to do much more.

Specifically, we'd want to see the Tx setup. what is the Tx MFGID?
Then it will likely be a case of emulating the Tx (or Rx) with the Devo radio/arduino and sending different packets during the binding phase, and see how the Tx/Rx respond.
Last edit: 09 Jun 2014 16:34 by PhracturedBlue.

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