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which is MJX use protocol ?
- john
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i know modul 2.4ghz , that is small board .
i wait someone write code use arduino , And we can use TX flysky + modul to control F45
great
problem is modul f45 is BK 2421 , NRF24L01 and CC2500
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- victzh
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- btoschi
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One can easily spot CE pin and 16MHz xtal plus epoxy covered chip, which tells us that this is a BK2421 (on F45 V3 RX board and TX) - and my sniffed SPI traffic confirms that.
F45 RX rev. 3
top
bottom
F45 TX (with red text on stickers)
btw: Tried to post this with huge images before, which did not work as expected. What's the size limit for images in this forum ?
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- FDR
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btoschi wrote: btw: Tried to post this with huge images before, which did not work as expected. What's the size limit for images in this forum ?
Image size should be fit within 800x800 pixels and max 256kB, however you can post zip files up to 1024kB...
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- victzh
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- btoschi
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And I have no V202 in my fleet yet ...
I'll try with your aduino code first, trying to get the nRF hooked up to the arduino ...
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- john
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however, modul BK2421 is range short. about 30m
i don't know where can buy modul range 1km
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- victzh
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Really, if you have a model that is visible at 1km and you can guide it, it costs so much you shouldn't save on transmitter. You shouldn't bother with Beken, go with nRF24L01+ with PA.
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- john
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i play helicopter MJX F45 and i had upgrade full motor brushless
now , i often fly outdoor , so i need range > 100m. i have two fail heli when control > 100m .OH no
as you say : modul NRF 24L01 = BK2421 ,them is suitable ?
i had modul NRF 24l01 + PA .
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- RandMental
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- btoschi
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Some SPI sniffing later (still using cheapo Scana Studio L.A.) I can confirm that the TX ID is in bytes 6-8 (byte 7-9 for not-coders ), my new TX has ID
Channel hopping for this TX is:
22 27 17 39 34 28 2B 1D
18 2A 21 38 0D 26 1D 1F
which is nearly the same as V2x2 Sequence 03, besides 10 replaced by 0D and 20 replaced by 1D (all values are hex). edit: Looking at the code, this is the strange avoidance of channels dividable by 16. Thus its the very same as V2x2.
Regarding the binding process it looks to me that TX simply transmits this packet (including command byte for BK2421, thus payload is 16 bytes):
A0 00 00 00 00 00 00 00 CE D5 00 00 00 00 00 C0 63
which looks just like the packet when being bound, besides C0 at the end and channels are all zero, and TX ID being only 2 bytes transmitted (maybe it is actually only 2 bytes ?).
Note that before triggering the actual bind process by pushing throttle up and down, it seems the TX transfers 16 bytes of uninitialized buffer (program bug?):
A0 C1 96 9A 1B 20 08 08 F2 7D EF FF 00 00 00 00 00
2E 41 10 04 82 20 08 08 F2 7F Ef FF
24 C1 96 9A 1B
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- btoschi
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I've tried to bind Arduino + nRF module to RX using your code but failed with that (disabled analog reads and used your auto-bind approach instead of throttle up/down).
I'm pretty sure I have not properly connected the nRF to my arduino mega (I have adjusted defines for CE/CSN), as I triple-checked arduino code and RX are programming the chip to send/listen on channel 8 (SPI cmd 0x25 0x08), so the initial bind procedure should work, and I even entered my original TX ID. There may be incoming traffic on RX side, but its not getting regularly packets ...
Any clues what I can check ? I do not own a spektral analyzer which I could use to check whether something is really sending data over the air ...
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- victzh
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The sequence transmitted in the very beginning appears to be garbage, V202 original transmitter does the same.
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- btoschi
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But even using MJX values
2A 6D 6A 73 73 73
2B 6A 6D 37 37 37
30 6D 6A 73 73 73
I have no V2x2 equipment and I did not find spare RX/TX for a reasonable price in europe (banggood has a V959 to V222 upgrade kit for a fair price, but that takes ages to germany due to customs inspections).
I do own a Devo 8s, but still prepare to mod it (Waiting for modules, reading howtos, ...).
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- victzh
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- john
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i want to see project when complete. If you can, post a video here ,test fly f45 ?
thank a lot and waitting.
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- SeByDocKy
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victzh wrote: Yea, I understand. May be after New Year when I reunite with my development environment I will be able to take another look at the situation. Anyway, if you're serious about reverse engineering, buy a cheap clone of Saleae, it costs around $10 and functions exactly the same.
I am interested ... by such clone. Eventually, you got a link for such product ?
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- PhracturedBlue
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Here is a list of the Saleae-like logic analyzers:
sigrok.org/wiki/Fx2lafw
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- SeByDocKy
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www.aliexpress.com/item/USB-Saleae-24M-8...t-1-1/823339465.html
I don't know if it's a good clone or not ... Anyway in worst case, I didn't loose a lot ... I want to learn retro-engeniering in protocol implementation.
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- btoschi
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victzh wrote: Anyway, if you're serious about reverse engineering, buy a cheap clone of Saleae, it costs around $10 and functions exactly the same.
I have ordered a original Saleae Logic at end of November (they were out of stock then, but estimated to ship until Christmas from UK ... still not arrived) and ordered a cheap clone after a colleage told me that he's interested in such a thing, too, so I can easily sell it when the original arrives. That one should be already in germany, hope to get it this week ...
I'm also trying to get a V222 (original or rebranded) for not too much money, but that may take some time (Did not yet see used/defective ones).
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