GPToys 993 Nano quadcopter

I got this one yesterday and it flies really nice. Of course i had to open TX and check inside. its using xn297 chip. I recorded the SPI communication and it looks like its using V2o2 protocol.
However when i tried running the deviationTX code (i dont own devo yet ... i am running the code on arduino (just the protocol code with some changes like the setup() and loop() functions) it does not bind.

My guess was, that the code is written for nrf24l01 and becouse this one is running on xn297 i need to change few things ?

anyway, i tried to decode the rest of the protocol and it looks it has 3 phases (just like V2o2):
- initialization ... this one looks really weird, missing a lot of stuff + setting additional registers of xn297, but not to the values from datasheet ...
- BIND: reciever starts sending the packet with bind flag set (this looks exactly as V2o2 ... except the channels are different (or i dont correctly understand the channel table in V2o2 code))
- when you move stick up/down TX_ADDR is changed (this does not happen for V2o2 ?)
- then the packet without the bind flag starts to be transmitted

packet is sent every 4ms

i tried searching the forum here and on rcgroups to find more info on xn297 but i am not sure i understand everything correctly ... the emulation layer of deviationTX ... it actually encodes the packet somehow ? well in my situation the packet looks exactly the same as for V2o2 (with no xn297 emulation?) so i am not sure i should be encoding anything ?
my assumption was i can just skip the special registers ... but its not working correctly.

i am wondering if anyone would have some time to help me out with this one ?

in the attachment you can find recording of the spi communication: powerup of TX (quad is already on), stick moved up/down so it binds. (you will need USBee AX Suite to open it)

xn297 transciever IC
Initialization
wait 30ms

before bindone packet every 3.9ms
bind
run

channels (before bind): 0x07, 0x24, 0x3e, 0x2b, 0x47, 0x0e, 0x39, 0x1c
channels (after bind) : 0x0f, 0x2a, 0x4b, 0x21, 0x2d, 0x36, 0x11, 0x35
channel is switched every second packet

i figured it out. I just replaced some calls with XN297_ emulation layer calls (setTxAdress, setRxAddress, writePayload) and now it works.

this should probably be added as an option to V2o2 protocol ?

ppisljar wrote: i figured it out. I just replaced some calls with XN297_ emulation layer calls (setTxAdress, setRxAddress, writePayload) and now it works.

this should probably be added as an option to V2o2 protocol ?

Well the V2x2 protocol is really nRF24L01 based .... maybe more a new option for any CX-10, Hantai, etc... XN297 protocol based ?

well this looks exactly V2o2 protocol, just that the chip in the transmitter/quad is XN297. the protocol does not resemble the CX-10 protocol. thats why i tought adding an option to V2o2 would be good idea (as maybe in the future more clones use x297 chip with this same protocol). It can also be added to cx10 protocol file but will need some more lines of code i guess.

Nice. Does seem best to add an option to the V202 protocol if none of the protocol logic is different.

I got more copters with ALMOUST identical protocol: MJX RC X800 and MJX RC X900 .

however i am looking for some feedback from people who put together the V202 protocol code, as some things are not completeley clear to me :

- TX and RX address .... are they something that was read out of copters ? or is it something random ?
u8 rx_tx_addr[] = {0x66, 0x88, 0x68, 0x68, 0x68};
u8 rx_p1_addr[] = {0x88, 0x66, 0x86, 0x86, 0x86};

for X800, x900 and GP993 this addresses are different. the RX_p1 doesnt really matter (i can change it to anything and it still works ? ) however the rx_tx address i must set to the one i read out of the original transmitter. else it doesnt work. i am not entirely sure how this works ? could somebody clarify ? like what does this actually mean ? shouldnt this be unique for every transmitter or sth like this ?


- the tx_id that is sent in a packet is 4 bytes (as oposed to 3 in the original V202)
- the channels are different. in V202 channels are based on tx_id ... however here i always use same channels (even if i randomize tx_id)
could someone explain how the channel table was put together for V202 ?
other things seem to be the same.