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Old Nov 04, 2012, 12:22 AM
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Quote:
Originally Posted by printk View Post
The CYRF69103 internally only use 3 wire SPI. I load up the
logic analyser and it capture the SPI data fine. Now I need to
read the datasheet to understand what it is dowing.
I think the trick for avoiding the wire break off the pad is that,
it need to use very thin wire. I am using 33 gauge wire. I don't
have smaller one. Also make sure the pin has good wetting
before the soldering.
Yeah, my finest wire is 30AWG, which is still too much. and my solder tip isn't really fine enough.
Anyhow, I got my RPi to bind with a DSM2 Rx, so now I just need to put the pieces together and I should be able to generate guid/channel pairs in a fully automated fashion.
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Old Nov 04, 2012, 12:43 AM
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Just jumping in here after quickly scanning the thread, but can it really be a pseudo-random sequence?

If it was. how would a receiver reconnect with a transmitter if there was a fade, reboot, etc? Surely it must be a deterministic sequence of some kind, perhaps even non repeating ?

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Old Nov 04, 2012, 03:16 AM
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Pseudo-random is called so for a reason - it's not random, but looks like it by statistical parameters. It is usually quite easily computable sequence if you know small number of parameters. See http://en.wikipedia.org/wiki/Pseudor...mber_generator It's not that easy to recover the parameters or algorithm if you know a sequence of examples.
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Old Nov 04, 2012, 01:51 PM
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The pesudo-random generator is used to map the GUID of the TX
to a 23 channel jumping sequence. The sequence is has a 1 to 1
mapping with the GUID. It only need to be calculate once at the
binding process in the receiver side, base on the GUID send by
the TX. The sequence does not change after the binding.

After the binding, the receiver will listen to packet arrive at this
channel sequence. It does not matter if the receiver has reboot
or not.

Quote:
Originally Posted by pmackenzie View Post
Just jumping in here after quickly scanning the thread, but can it really be a pseudo-random sequence?

If it was. how would a receiver reconnect with a transmitter if there was a fade, reboot, etc? Surely it must be a deterministic sequence of some kind, perhaps even non repeating ?

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Old Nov 04, 2012, 01:58 PM
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Does your RPi talk to talk to the walkera TX module and snoop the
receiver SPI bus at the same time? I have RPi and walkera TX.
Maybe I can duplicate your setup. My current setup is using a
130x receiver chip CYRF69103 on a MCPX 3 in 1 board. I can
snoop the 3 wire SPI bus fine.

Just a thought, would it be possible if I open a DX4e TX
module shielding case, put the SPI trace on the TX side?
It does not require the reboot of the receiver chip to send new
binding sequence. It might able to get the GUID to channel
sequence faster. Comments?

Quote:
Originally Posted by PhracturedBlue View Post
Anyhow, I got my RPi to bind with a DSM2 Rx, so now I just need to put the pieces together and I should be able to generate guid/channel pairs in a fully automated fashion.
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Old Nov 04, 2012, 02:10 PM
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I hooked the RPi up to a spare (non-telemetry) walkera module I had lying around using SPI

I'm using the DSM2 code I wrote for Deviation (setup to send DSMX), I needed to rewrite the SPI routines, but otherwise, it seems to work well. Linux does get interrupts meaning it probably isn't reliable enough to hold the bind for long, but seems to be good enough for this testing.

Basically, I've got my Saleae Logic capturing long chains from a 6102Rx, and have the RPi transmitting different GUIDs. I use a GPIO with an nfet to power on the Rx, seind binding codes, wait a little while, power off the Rx (via GPIO) and repeat.Then I dump the csv from the Saleae Logic, and use some perl to extract the sequence.

I'm still having a few issues with timing, so it isn't quite working yet, but it is very close.

I can only capture 10mins or so at a time with the Saleae Software. I may try sigrok to see if I can capture a couple hours of data at a time.

Edit: Once I get the code debugged, I'll post it. It is very simple.
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Old Nov 04, 2012, 04:31 PM
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Very interesting investigation... Some thoughts:

The Tx and Rx can be turned on at different times. How do they both know where the other is in the sequence?

If I were designing this my first thought would be to use the GUID as the seed to the RNG. Then run the RNG for 1 cycle through the set of channels. Then the Rx just has to wait for the Tx to send a packet on one channel. When it detects that packet it knows where the Tx is in the sequence and it knows what channel to listen to next and synchronization is achieved. One indication that this is likely the protocol is that synchronization takes a variable amount of time.

Another problem with the RNG idea: RNGs produce numbers that repeat. The simplest algorithm that avoids this is to ignore the RNG value if its a repeat and go on to the next value. i.e. in psudo code:

RNG rand = new RNG(guid);
Array<byte> sequence = new Array<byte>[72];
int i = 0;
byte nextVal;
while (i < 72) {
nextVal = rand.next();
if (!sequence.contains(nextVal)) {
sequence.push(nextVal);
}
}

My next thought is that the chips that are used in the Tx and Rx may change over time. If the algorithm used to derive the the sequence is dependent on something in hardware they would be stuck using that chip forever. If it was me, I would code my own RNG function so it could be ported to any chip in the future. (Maybe use the one provided in C since that should be portable.) That opens up the possibility of other implementations that are not RNG based.

Just the musings of a programmer, carry on.
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Old Nov 04, 2012, 04:55 PM
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racerxky, The random sequence is only use at mapping a GUID to the channel sequence.
My understanding is that, once the receiver is already bound to a TX GUID, the channel
jump sequence will not change. The channel jumping sequence is determined by the GUID.
It will just receive the package from the first channel, then go to the next one to receive.

The receiver does not know the timing when the TX send the first packet. It just wait
at that channel until it receive the packet from TX. Once RX receive the first packet.
The time frame a in sync. If the RX receive a packet that is send by other TX, so the
next packet will not arrive, because the other TX will likely using a different jumping
sequence. I assume RX will detect a time out on the next packet in the expecting
sequence. Then it will retry on receiving the first packet again.
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Old Nov 04, 2012, 05:07 PM
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I don't think my DX4e TX module idea will work, because it seems that DX4e
can't send arbitrate GUID. It can only use a model number to index to the
pre-determine GUID for that model.

PhracturedBlue, how many bytes are send per channel before it jump to
the next channel? Do we know the data format of the packet it send out?

I have the Devo telemetric module, the non telemetric TX module is still
in my Devo8. Is it possible to let a micro controller to decode the SPI?
It seems on the 3 wire SPI bus, it should be able to use the SPI feature
of the micro controller to decode it. Then process it only take out the
sequence.

Do you have some example SPI bus data, how to exact the sequence
from it?

I only have the DX4e module with ER9x. It seems the firmware is only
doing DSM2. I did not find the DSMX code in the firmware source code.
Currently I don't have real DSMX TX to trigger bind to the receiver unless
I use the walkera module and some hacking.
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Old Nov 04, 2012, 05:17 PM
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Quote:
Originally Posted by printk View Post
I only have the DX4e module with ER9x. It seems the firmware is only
doing DSM2. I did not find the DSMX code in the firmware source code.
Currently I don't have real DSMX TX to trigger bind to the receiver unless
I use the walkera module and some hacking.
OT, but DSMX is supported in ER9X with the DX4e module.
Select DSM2/DSMX as the type of DSM2 protocol.
The header bytes sent to the module by ER9X are changed and the module takes care of the rest.

You have to go though a bind operation to "switch" the module between the two modes, so once you are bound to a DSMX receiver any previously bound DSM2 receivers won't work anymore. (And visa versa)

PM me, or ask about it in the 9X custom firmware thread if you have any more questions.


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Old Nov 04, 2012, 05:28 PM
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pmackenzie,

Thanks for the quick reply. Then I should be able to get a DSMX
SPI trace using my ER9x and DX4e module. Great.
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Old Nov 04, 2012, 05:39 PM
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Quote:
Originally Posted by printk View Post
pmackenzie,

Thanks for the quick reply. Then I should be able to get a DSMX
SPI trace using my ER9x and DX4e module. Great.
inside the module, between its processor and the RF chip.
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Old Nov 04, 2012, 05:44 PM
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Quote:
Originally Posted by printk View Post
PhracturedBlue, how many bytes are send per channel before it jump to
the next channel? Do we know the data format of the packet it send out?
one frame (16 bytes) per channel. The firmware actually runs a seek algroithm oon power up alternating between acending and descending channels until it locates a signal and locks on. the data format is the same as DSM2 but the SOP codes are different

Quote:
I have the Devo telemetric module, the non telemetric TX module is still
in my Devo8. Is it possible to let a micro controller to decode the SPI?
It seems on the 3 wire SPI bus, it should be able to use the SPI feature
of the micro controller to decode it. Then process it only take out the
sequence.
sure, processing it is easy enough. I'm not sure what you are trying to achieve though. you need something either Tx or Rx to generate the sequence, and you need some way to convince it to use a custom GUI to generate that sequence.

you could attach a uC to the SPI bus on the Rx, and put it in slave mode to snoop the signal, but that is all that a logic analyzer is doing, so I'm not sure what you gain.

Using a uC to drive the Walkera module, it is easy to generate a custom GUID. Using a logic analyzer on the Rx it is easy to snag the sequence. tying these together into one prcoess is proving more annoying than I'd exected.

Quote:
Do you have some example SPI bus data, how to exact the sequence
from it?
sure, here is the sequence for GUID 100 (0x64):
Code:
       3.857767# 21 21 0f 00 00 00 64 00 00 00 64 02 38 01 07 a2 00
       3.857855: 8f 2c
       3.857871# 0f 01
       3.857895: 85 83
       3.857911# 13 01
       3.867720# 07 07
       3.867732# 02
       3.867751# 09 95
       3.867770# 21 21 0f 00 00 00 64 00 00 00 64 02 38 01 07 a2 00
       3.867859: 8f 2c
       3.867874# 0f 01
       3.867898: 85 83
       3.867914# 13 01
       3.880046: a9 20
       3.880094# 13 00
       3.880114: 8f 2c
       3.880130# 0f 01
       3.880151: a9 00
       3.958825: a5 ff
       3.958844# 25 25 05 43 38 56 a9
       3.958900: a5 00
       4.033871: 83 2f
       4.033888: 90 ee
       4.033904: 9f 00
       4.033921: 9e 00
       4.033966: a9 00
       4.034140: d5 00 00
       4.034178: a2 40 ba 97 d5 86 4f cc d1
       4.034360: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.034693: 80 43
       4.034712: 8e 00
       4.034733: 85 83
       4.034749# 13 01
       4.056170: a9 20
       4.056217# 13 00
       4.056238: 8f 2c
       4.056254# 0f 01
       4.056274: a9 00
       4.056452: d5 ff ff
       4.056490: a2 9e 08 d1 ae 59 5e e8 f0
       4.056672: a3 40 56 32 d9 0f d9 5d 97 8e 4a d0 a9 a7 ff 20 ca
       4.057005: 80 1d
       4.057024: 8e 20
       4.057045: 85 83
       4.057061# 13 01
       4.060232: a9 20
       4.060280# 13 00
       4.060300: 8f 2c
       4.060316# 0f 01
       4.060337: a9 00
       4.060508: d5 00 00
       4.060547: a2 9e 08 d1 ae 59 5e e8 f0
       4.060728: a3 40 56 32 d9 0f d9 5d 97 8e 4a d0 a9 a7 ff 20 ca
       4.061061: 80 09
       4.061080: 8e 00
       4.061101: 85 83
       4.061117# 13 01
       4.078385: a9 20
       4.078432# 13 00
       4.078453: 8f 2c
       4.078469# 0f 01
       4.078489: a9 00
       4.078669: d5 ff ff
       4.078707: a2 35 d1 fc 97 23 d4 c9 88
       4.078889: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.079222: 80 4b
       4.079241: 8e 20
       4.079262: 85 83
       4.079278# 13 01
       4.082442: a9 20
       4.082490# 13 00
       4.082510: 8f 2c
       4.082526# 0f 01
       4.082547: a9 00
       4.082720: d5 00 00
       4.082758: a2 35 d1 fc 97 23 d4 c9 88
       4.082940: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.083273: 80 41
       4.083293: 8e 00
       4.083313: 85 83
       4.083329# 13 01
       4.100597: a9 20
       4.100644# 13 00
       4.100665: 8f 2c
       4.100681# 0f 01
       4.100702: a9 00
       4.100879: d5 ff ff
       4.100916: a2 35 d1 fc 97 23 d4 c9 88
       4.101098: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.101431: 80 23
       4.101450: 8e 20
       4.101471: 85 83
       4.101487# 13 01
       4.104659: a9 20
       4.104706# 13 00
       4.104726: 8f 2c
       4.104742# 0f 01
       4.104763: a9 00
       4.104933: d5 00 00
       4.104971: a2 40 ba 97 d5 86 4f cc d1
       4.105153: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.105486: 80 2f
       4.105505: 8e 00
       4.105526: 85 83
       4.105542# 13 01
       4.122810: a9 20
       4.122857# 13 00
       4.122878: 8f 2c
       4.122893# 0f 01
       4.122914: a9 00
       4.123092: d5 ff ff
       4.123130: a2 5f 30 3b 56 96 45 f4 a1
       4.123312: a3 e1 d6 31 26 5f bd 40 93 dc 68 08 99 97 ae af 8c
       4.123646: 80 15
       4.123665: 8e 20
       4.123685: 85 83
       4.123702# 13 01
       4.126873: a9 20
       4.126920# 13 00
       4.126940: 8f 2c
       4.126957# 0f 01
       4.126977: a9 00
       4.127148: d5 00 00
       4.127187: a2 35 d1 fc 97 23 d4 c9 88
       4.127368: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.127702: 80 2d
       4.127721: 8e 00
       4.127741: 85 83
       4.127758# 13 01
       4.145025: a9 20
       4.145073# 13 00
       4.145093: 8f 2c
       4.145109# 0f 01
       4.145130: a9 00
       4.145308: d5 ff ff
       4.145345: a2 62 f5 2b aa fc 33 bf af
       4.145527: a3 83 f7 a8 2d 7a 44 64 d3 3f 2c 4e aa 71 48 7a c9
       4.145860: 80 35
       4.145880: 8e 20
       4.145900: 85 83
       4.145917# 13 01
       4.149088: a9 20
       4.149135# 13 00
       4.149156: 8f 2c
       4.149172# 0f 01
       4.149192: a9 00
       4.149361: d5 00 00
       4.149398: a2 40 ba 97 d5 86 4f cc d1
       4.149580: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.149913: 80 07
       4.149932: 8e 00
       4.149953: 85 83
       4.149969# 13 01
       4.167244: a9 20
       4.167291# 13 00
       4.167312: 8f 2c
       4.167328# 0f 01
       4.167349: a9 00
       4.167526: d5 ff ff
       4.167563: a2 5f 30 3b 56 96 45 f4 a1
       4.167745: a3 e1 d6 31 26 5f bd 40 93 dc 68 08 99 97 ae af 8c
       4.168078: 80 1f
       4.168098: 8e 20
       4.168119: 85 83
       4.168134# 13 01
       4.171306: a9 20
       4.171353# 13 00
       4.171374: 8f 2c
       4.171390# 0f 01
       4.171410: a9 00
       4.171583: d5 00 00
       4.171622: a2 5f 30 3b 56 96 45 f4 a1
       4.171804: a3 e1 d6 31 26 5f bd 40 93 dc 68 08 99 97 ae af 8c
       4.172138: 80 1f
       4.172157: 8e 00
       4.172177: 85 83
       4.172193# 13 01
       4.189461: a9 20
       4.189508# 13 00
       4.189529: 8f 2c
       4.189544# 0f 01
       4.189565: a9 00
       4.189738: d5 ff ff
       4.189776: a2 40 ba 97 d5 86 4f cc d1
       4.189958: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.190291: 80 07
       4.190310: 8e 20
       4.190331: 85 83
       4.190347# 13 01
       4.193518: a9 20
       4.193566# 13 00
       4.193586: 8f 2c
       4.193602# 0f 01
       4.193623: a9 00
       4.193796: d5 00 00
       4.193834: a2 62 f5 2b aa fc 33 bf af
       4.194015: a3 83 f7 a8 2d 7a 44 64 d3 3f 2c 4e aa 71 48 7a c9
       4.194349: 80 35
       4.194368: 8e 00
       4.194388: 85 83
       4.194405# 13 01
       4.211672: a9 20
       4.211719# 13 00
       4.211740: 8f 2c
       4.211755# 0f 01
       4.211776: a9 00
       4.211951: d5 ff ff
       4.211989: a2 35 d1 fc 97 23 d4 c9 88
       4.212170: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.212503: 80 2d
       4.212523: 8e 20
       4.212543: 85 83
       4.212559# 13 01
       4.215731: a9 20
       4.215778# 13 00
       4.215799: 8f 2c
       4.215814# 0f 01
       4.215835: a9 00
       4.216009: d5 00 00
       4.216047: a2 5f 30 3b 56 96 45 f4 a1
       4.216229: a3 e1 d6 31 26 5f bd 40 93 dc 68 08 99 97 ae af 8c
       4.216562: 80 15
       4.216582: 8e 00
       4.216602: 85 83
       4.216619# 13 01
       4.233886: a9 20
       4.233933# 13 00
       4.233954: 8f 2c
       4.233970# 0f 01
       4.233991: a9 00
       4.234166: d5 ff ff
       4.234204: a2 40 ba 97 d5 86 4f cc d1
       4.234386: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.234719: 80 2f
       4.234738: 8e 20
       4.234759: 85 83
       4.234775# 13 01
       4.237947: a9 20
       4.237994# 13 00
       4.238015: 8f 2c
       4.238030# 0f 01
       4.238051: a9 00
       4.238224: d5 00 00
       4.238263: a2 35 d1 fc 97 23 d4 c9 88
       4.238444: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.238777: 80 23
       4.238797: 8e 00
       4.238818: 85 83
       4.238834# 13 01
       4.256101: a9 20
       4.256148# 13 00
       4.256169: 8f 2c
       4.256185# 0f 01
       4.256206: a9 00
       4.256383: d5 ff ff
       4.256420: a2 35 d1 fc 97 23 d4 c9 88
       4.256602: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.256935: 80 41
       4.256954: 8e 20
       4.256975: 85 83
       4.256991# 13 01
       4.260162: a9 20
       4.260209# 13 00
       4.260230: 8f 2c
       4.260246# 0f 01
       4.260267: a9 00
       4.260442: d5 00 00
       4.260480: a2 35 d1 fc 97 23 d4 c9 88
       4.260662: a3 c0 90 8f bb 7c 8e 2b 8e 80 69 26 80 08 f8 49 e7
       4.260995: 80 4b
       4.261015: 8e 00
       4.261036: 85 83
       4.261052# 13 01
       4.278312: a9 20
       4.278360# 13 00
       4.278380: 8f 2c
       4.278396# 0f 01
       4.278416: a9 00
       4.278592: d5 ff ff
       4.278629: a2 9e 08 d1 ae 59 5e e8 f0
       4.278810: a3 40 56 32 d9 0f d9 5d 97 8e 4a d0 a9 a7 ff 20 ca
       4.279144: 80 09
       4.279163: 8e 20
       4.279184: 85 83
       4.279200# 13 01
       4.282371: a9 20
       4.282419# 13 00
       4.282439: 8f 2c
       4.282455# 0f 01
       4.282476: a9 00
       4.282649: d5 00 00
       4.282687: a2 9e 08 d1 ae 59 5e e8 f0
       4.282869: a3 40 56 32 d9 0f d9 5d 97 8e 4a d0 a9 a7 ff 20 ca
       4.283202: 80 1d
       4.283222: 8e 00
       4.283243: 85 83
       4.283259# 13 01
       4.300526: a9 20
       4.300573# 13 00
       4.300594: 8f 2c
       4.300610# 0f 01
       4.300631: a9 00
       4.300808: d5 ff ff
       4.300845: a2 40 ba 97 d5 86 4f cc d1
       4.301027: a3 03 bc 6e 8a ef bd fe f8 88 17 13 3b 2d bf 06 d6
       4.301360: 80 43
the 1st column is time, a ':' marks a write, whereas a '#' marks a read. I parse it by finding the last data reception (# 21), then reading the next 46 channel changed (: 80). Ignore every other one and you have the sequence.
Note that you ignore the '21 0f' in the data packet. the data packet starts at the 3rd byte and is '<32-bit guid> <32bit guid> <16bit crc> 01 <#chan 8-bit> <0xa2 (DSMX)> <00>'
the last 2 bytes would be another CRC, but I don't see them being read on my Satellite.
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Old Nov 04, 2012, 05:47 PM
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Quote:
Originally Posted by printk View Post
pmackenzie,

Thanks for the quick reply. Then I should be able to get a DSMX
SPI trace using my ER9x and DX4e module. Great.
I'd be really surprised if you can set the GUID for the DX4e module. The GUID by default is the CRYFID + the model#, so it is likely comletely contained inside the module.
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Old Nov 04, 2012, 05:56 PM
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I am not trying to set a GUID in the DX4e, it seems that is not possible.
I am just trying to get a DSMX trace using my MCPX/130x receiver chip.
I don't own DX8 and dedicate DSMX receiver yet.
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Wanted JR9503 DSMX or JR 11X DSMX and AR9200/AR9210 Receiver w/sats patrick21x Aircraft - General - Radio Equipment (FS/W) 0 Nov 17, 2011 11:22 PM
Discussion WALKERA 2.4 TX hack -can YOU hack it? aaronstomfoolery Radios 2 Oct 29, 2011 05:44 AM
Sold NNIB AR6210 DSMX w/sat + AR600 DSMX GeetarJoe Aircraft - General - Radio Equipment (FS/W) 0 Oct 19, 2011 02:50 AM