MJX Protocol?

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21 Dec 2012 22:56 #4160 by DarkWolf
MJX Protocol? was created by DarkWolf
Hey.. I'm not sure if this has been covered, or if MJX is supported yet but I thought I'd check. Been trying to bind to an MJX F45 and so far I've not been able to. Any ideas?

Thanks!

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22 Dec 2012 09:44 #4166 by FDR

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22 Dec 2012 14:30 #4180 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
So I'm not missing something and I'm not screwing up the settings and failing to get it to bind... It's just not supported yet.

I'm not even remotely sure of what the protocols are based off of, so not sure if it'd even be accepted, but I'd surely be willing to pick up a spare rx and send over.

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22 Dec 2012 14:58 #4182 by PhracturedBlue
Replied by PhracturedBlue on topic MJX Protocol?
looking at images of the receiver, the transceiver chip appears to be on a daughter board soldered underneath the main rx board. That is annoying because it makes it hard to see which chips are being used, and this is the 1st thing I'd need to know. If you want to open the transmitter and take pictures of the inside, it could help identify which chips are being used.

It looks like I could pick up a receiver and tx for ~$40 US, which isn't too bad, but if it only supports 1 model, it may not really be worth it. It will probably depend on which chips are being used.

The Rx by itself isn't particularly useful for protocol development. need a rx and tx pair usually.

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22 Dec 2012 16:30 #4190 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
Several of the MJX line use the same TX, so I'd think it safe that it works for all. Let me double check though with those in the know as there are two versions of the TX. I'm fairly certain though that it's just cosmetic? From the looks of their 2013 catalog, there's also a third style TX, but it may be cosmetic as well.

I'll split the TX in a bit and take several macro shots for you, see if that doesn't help.

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22 Dec 2012 17:13 - 22 Dec 2012 17:14 #4193 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
These are all high res. The last has been labeled with the chip IDs. The main chip seems to be made by a company called LAN, but it's hard to get a photo of their logo, which is a script style L to the left of LAN which is unprinted, encased in a box.








Hope this helps ID it.. If you need any further details or pictures, just let me know.

I SHOULD have all the numbers correct, but 1s may be Is and 0s may be Os. Beyond that, it should be good.
Last edit: 22 Dec 2012 17:14 by DarkWolf.

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22 Dec 2012 17:40 #4195 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
The transceiver on the RX is indeed soldered on under the main board. Beyond the crystal, there's just a black blob chip with no distinct markings. Pin out from the daughter board from top to bottom (right to left facing the pins) is:

CSN
IRQ
GND
CE
MISC
SCK
MOSI
+3.3V


There is an odd pathway etched in to the front which may or may not be some kind of ID mark.

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22 Dec 2012 17:49 #4196 by PhracturedBlue
Replied by PhracturedBlue on topic MJX Protocol?
the important one is actually the one underneath the black circle (the silicon is mounted right on the board, without a package). Assuming they went for cost savings, it is likely an oem board that they use rather than designing their own RF board. The problem is it makes it harder to identify which chip is in use

The rfx2402c on the same board is the power-amp.

Can you see if there are any numbers on the crystal on the rf board (the silver oval). Knowing the frequency may help identify which transceiver is being used.
My guess is it is an nrf24l01, but there's really no data backing that up at the moment.

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22 Dec 2012 17:57 #4197 by PhracturedBlue
Replied by PhracturedBlue on topic MJX Protocol?
that etched wire on the rx is the antenna.

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22 Dec 2012 18:14 #4199 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?

PhracturedBlue wrote: that etched wire on the rx is the antenna.


Duh me.. I should have considered that.

Frequency labeled is 16.000

There are only 3 TXs in the MJX lineup. The GR-129 being the most prevalent now, followed by the GR-146 which seems to be packed with their newest and upcoming releases. The GR-40C is limited to their T-series coax helis.

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22 Dec 2012 18:41 #4200 by PhracturedBlue
Replied by PhracturedBlue on topic MJX Protocol?
well, the cyrf6936 uses a 12MHz crystal, the CC2500 uses a 26MHz crystal.
The nrf24l01 uses a 16MHz crystal. the cc2520 uses a 32MHz crystal. The A7105 can use 8, 12, 16, 20, 24 MHZ crystals
So that leaves us with the nrf24L01, the A7105, or some other unknown chip.

The A7105 is used in Flysky equipment, and is not a very big player. The NRF24L01 is very popular with RC equipment.

In either case, to use it with Deviation, you'll need to add a new module. You can look at the Flysky to Devo pdf to get an idea of the procedure (though that is only the hardware part. We still need to know the protocol.

I haven't yet put an nrf24L01 module in my tx, though it is a part of my protocol-analysis test rig.

If you're still interested, I may consider ordering an rx and tx. $40 isn't a bad deal, and the transmitter module itself is easily worth $10 with its nice 23dB power-amp

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22 Dec 2012 19:20 #4201 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
Well, picking up a V911 was certainly on my list of things to do, so installing a module into the 8S was also.


Now... In the doc it states "XL7105-D03 is an A7105 transceiver" but also gives reference to the NRF24L01 in the URLs provided. Will that module work with both A7105 and NRF24L01 transceivers?

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22 Dec 2012 19:38 - 22 Dec 2012 19:52 #4202 by DarkWolf
Replied by DarkWolf on topic MJX Protocol?
BTW, I split the TX down and took a couple more pictures. Though I doubt they'll be of much use.





Pin out from the top down on the module is:
RXEN - CSN - IRQ - GND - CE - MISO - SCK - MOSI - +3.3V

And yes, I'm certainly still interested, regardless of mod. If it does end up being the same work required (besides protocol) to get the V911 up, I'm sure others would be interested as well.
Last edit: 22 Dec 2012 19:52 by DarkWolf. Reason: Typo

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07 Apr 2013 23:38 #8722 by victzh
Replied by victzh on topic MJX Protocol?
CE pin is a telltale sign of Nordic nRF24L01 as we found recently. It's radio enable for the chip. And I guess that it's not a genuine nRF24L01 but its clone, Beken BK2421 or BK2423. They do make direct die on PCB. Also, judging by relative position of signal pins, crystal and radio, it looks like Beken/Nordic (they have the same pinout). One more sign - I have a radio board in WL Toys V202 TX with exact same pinout, but with regular chip, marked BK2423.

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08 Apr 2013 01:13 #8724 by PhracturedBlue
Replied by PhracturedBlue on topic MJX Protocol?
FYI, I ordered a Tx and Rx board. For $34US, seems like a good deal. I probably won't have time to work on this anytime soon, but then it'll likely take a month to get here...

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07 Jul 2013 14:06 #12035 by PeaTearGryphon
Replied by PeaTearGryphon on topic MJX Protocol?

PhracturedBlue wrote: FYI, I ordered a Tx and Rx board. For $34US, seems like a good deal. I probably won't have time to work on this anytime soon, but then it'll likely take a month to get here...


Any update on this?

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02 Aug 2013 07:50 #12720 by john
Replied by john on topic MJX Protocol?
F45 use modul nrf24l01 ? can repalce TX by TX flysky 9ch ?

i find project here www.rcgroups.com/forums/showthread.php?t=1564343

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11 Sep 2013 05:59 #13702 by john
Replied by john on topic MJX Protocol?
mjxf45 use protocol CC2500 , xtal is 26mhz , pin 8 and 10

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16 Oct 2013 13:15 #14703 by andmiller
Replied by andmiller on topic MJX Protocol?
I am also curious if anyone has been working on this, MJX has been releasing some pretty good copters as of late.
Thanks

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09 Dec 2013 22:36 #16456 by btoschi
Replied by btoschi on topic MJX Protocol?
Check my post here: www.deviationtx.com/forum/protocol-devel...x-use-protocol#16167

I'll report my findings in that thread.
Short summary: The RF chip is a BK2421 and according to victzh protocol looks similar to V202, more to come.

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